/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkTextureObject.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkTextureObject.h"

#include "vtk_glew.h"

#include "vtkObjectFactory.h"


#include "vtkNew.h"
#include "vtkOpenGLBufferObject.h"
#include "vtkOpenGLError.h"
#include "vtkOpenGLRenderUtilities.h"
#include "vtkOpenGLRenderWindow.h"
#include "vtkOpenGLResourceFreeCallback.h"
#include "vtkOpenGLShaderCache.h"
#include "vtkOpenGLTexture.h"
#include "vtkOpenGLVertexArrayObject.h"
#include "vtkPixelBufferObject.h"
#include "vtkRenderer.h"
#include "vtkShaderProgram.h"

#include "vtkOpenGLHelper.h"

#include <cassert>

//#define VTK_TO_DEBUG
//#define VTK_TO_TIMING

#ifdef VTK_TO_TIMING
#include "vtkTimerLog.h"
#endif

#include "vtkTextureObjectFS.h"
#include "vtkTextureObjectVS.h"  // a pass through shader

#define BUFFER_OFFSET(i) (reinterpret_cast<char *>(i))

// Mapping from DepthTextureCompareFunction values to OpenGL values.
//----------------------------------------------------------------------------
static GLint OpenGLDepthTextureCompareFunction[8]=
{
  GL_LEQUAL,
  GL_GEQUAL,
  GL_LESS,
  GL_GREATER,
  GL_EQUAL,
  GL_NOTEQUAL,
  GL_ALWAYS,
  GL_NEVER
};

//----------------------------------------------------------------------------
static const char *DepthTextureCompareFunctionAsString[8]=
{
  "Lequal",
  "Gequal",
  "Less",
  "Greater",
  "Equal",
  "NotEqual",
  "AlwaysTrue",
  "Never"
};

// Mapping from Wrap values to OpenGL values
#if GL_ES_VERSION_3_0 != 1
  //--------------------------------------------------------------------------
  static GLint OpenGLWrap[4]=
  {
    GL_CLAMP_TO_EDGE,
    GL_REPEAT,
    GL_MIRRORED_REPEAT,
    GL_CLAMP_TO_BORDER
  };

  //--------------------------------------------------------------------------
  static const char *WrapAsString[4]=
  {
    "ClampToEdge",
    "Repeat",
    "MirroredRepeat",
    "ClampToBorder"
  };

#else
  //--------------------------------------------------------------------------
  static GLint OpenGLWrap[3]=
  {
    GL_CLAMP_TO_EDGE,
    GL_REPEAT,
    GL_MIRRORED_REPEAT
  };

  //--------------------------------------------------------------------------
  static const char *WrapAsString[3]=
  {
    "ClampToEdge",
    "Repeat",
    "MirroredRepeat"
  };

#endif

// Mapping MinificationFilter values to OpenGL values.
//----------------------------------------------------------------------------
static GLint OpenGLMinFilter[6]=
{
  GL_NEAREST,
  GL_LINEAR,
  GL_NEAREST_MIPMAP_NEAREST,
  GL_NEAREST_MIPMAP_LINEAR,
  GL_LINEAR_MIPMAP_NEAREST,
  GL_LINEAR_MIPMAP_LINEAR
};

// Mapping MagnificationFilter values to OpenGL values.
//----------------------------------------------------------------------------
static GLint OpenGLMagFilter[6]=
{
  GL_NEAREST,
  GL_LINEAR
};

//----------------------------------------------------------------------------
static const char *MinMagFilterAsString[6]=
{
  "Nearest",
  "Linear",
  "NearestMipmapNearest",
  "NearestMipmapLinear",
  "LinearMipmapNearest",
  "LinearMipmapLinear"
};

//----------------------------------------------------------------------------
static GLenum OpenGLDepthInternalFormat[7]=
{
  GL_DEPTH_COMPONENT, // native
  GL_DEPTH_COMPONENT, // fixed8
  GL_DEPTH_COMPONENT16, //fixed16
#ifdef GL_DEPTH_COMPONENT24
  GL_DEPTH_COMPONENT24, //fixed24
#else
  GL_DEPTH_COMPONENT16,
#endif
#ifdef GL_DEPTH_COMPONENT32
  GL_DEPTH_COMPONENT32, // fixed32
#else
  GL_DEPTH_COMPONENT16,
#endif
#ifdef GL_DEPTH_COMPONENT32F
  GL_DEPTH_COMPONENT32F, // float16
  GL_DEPTH_COMPONENT32F  // float32
#else
  GL_DEPTH_COMPONENT16,
  GL_DEPTH_COMPONENT16
#endif
};

//----------------------------------------------------------------------------
static GLenum OpenGLDepthInternalFormatType[7]=
{
  GL_UNSIGNED_INT,
  GL_UNSIGNED_INT,
  GL_UNSIGNED_INT,
  GL_UNSIGNED_INT,
  GL_UNSIGNED_INT,
#ifdef GL_DEPTH_COMPONENT32F
  GL_FLOAT,
  GL_FLOAT
#else
  GL_UNSIGNED_INT,
  GL_UNSIGNED_INT
#endif
};

//----------------------------------------------------------------------------
vtkStandardNewMacro(vtkTextureObject);

//----------------------------------------------------------------------------
vtkTextureObject::vtkTextureObject()
{
  this->Context = nullptr;
  this->Handle = 0;
  this->NumberOfDimensions = 0;
  this->Target = 0;
  this->Components = 0;
  this->Width = 0;
  this->Height = 0;
  this->Depth = 0;
  this->Samples = 0;
  this->RequireTextureInteger = false;
  this->SupportsTextureInteger = false;
  this->RequireTextureFloat = false;
  this->SupportsTextureFloat = false;
  this->RequireDepthBufferFloat = false;
  this->SupportsDepthBufferFloat = false;
  this->AutoParameters = 1;
  this->WrapS = Repeat;
  this->WrapT = Repeat;
  this->WrapR = Repeat;
  this->MinificationFilter = Nearest;
  this->MagnificationFilter = Nearest;
  this->MinLOD = -1000.0f;
  this->MaxLOD = 1000.0f;
  this->BaseLevel = 0;
  this->MaxLevel = 0;
  this->DepthTextureCompare = false;
  this->DepthTextureCompareFunction = Lequal;
  this->GenerateMipmap = false;
  this->ShaderProgram = nullptr;
  this->BorderColor[0] = 0.0f;
  this->BorderColor[1] = 0.0f;
  this->BorderColor[2] = 0.0f;
  this->BorderColor[3] = 0.0f;
  this->BufferObject = nullptr;
  this->UseSRGBColorSpace = false;

  this->ResourceCallback = new vtkOpenGLResourceFreeCallback<vtkTextureObject>(this,
    &vtkTextureObject::ReleaseGraphicsResources);

  this->ResetFormatAndType();
}

//----------------------------------------------------------------------------
vtkTextureObject::~vtkTextureObject()
{
  if (this->ResourceCallback)
  {
    this->ResourceCallback->Release();
    delete this->ResourceCallback;
    this->ResourceCallback = nullptr;
  }
  if (this->ShaderProgram)
  {
    delete this->ShaderProgram;
    this->ShaderProgram = nullptr;
  }
}

//----------------------------------------------------------------------------
bool vtkTextureObject::IsSupported(vtkOpenGLRenderWindow* vtkNotUsed(win),
      bool requireTexFloat,
      bool requireDepthFloat,
      bool requireTexInt)
{
#if GL_ES_VERSION_3_0 == 1
  return true;
#else
  if (vtkOpenGLRenderWindow::GetContextSupportsOpenGL32())
  {
    return true;
  }
  bool texFloat = true;
  if (requireTexFloat)
  {
    texFloat = (glewIsSupported("GL_ARB_texture_float") != 0
     && glewIsSupported("GL_ARB_texture_rg") != 0);
  }

  bool depthFloat = true;
  if (requireDepthFloat)
  {
    depthFloat = (glewIsSupported("GL_ARB_depth_buffer_float") != 0);
  }

  bool texInt = true;
  if (requireTexInt)
  {
    texInt = (glewIsSupported("GL_EXT_texture_integer") != 0);
  }

  return texFloat && depthFloat && texInt;
#endif
}

//----------------------------------------------------------------------------
bool vtkTextureObject::LoadRequiredExtensions(vtkOpenGLRenderWindow *renWin)
{
#if GL_ES_VERSION_3_0 == 1
  this->SupportsTextureInteger = true;
  this->SupportsTextureFloat = true;
  this->SupportsDepthBufferFloat = true;
#else
  if (vtkOpenGLRenderWindow::GetContextSupportsOpenGL32())
  {
    this->SupportsTextureInteger = true;
    this->SupportsTextureFloat = true;
    this->SupportsDepthBufferFloat = true;
  }
  else
  {
    this->SupportsTextureInteger =
      (glewIsSupported("GL_EXT_texture_integer") != 0);

    this->SupportsTextureFloat =
      (glewIsSupported("GL_ARB_texture_float") != 0 &&
       glewIsSupported("GL_ARB_texture_rg") != 0);

    this->SupportsDepthBufferFloat =
      (glewIsSupported("GL_ARB_depth_buffer_float") != 0);
  }
#endif

  return this->IsSupported(renWin,
    this->RequireTextureFloat,
    this->RequireDepthBufferFloat,
    this->RequireTextureInteger);
}

//----------------------------------------------------------------------------
void vtkTextureObject::SetContext(vtkOpenGLRenderWindow* renWin)
{
  this->ResourceCallback->RegisterGraphicsResources(renWin);

  // avoid pointless reassignment
  if (this->Context == renWin)
  {
    return;
  }

  this->ResetFormatAndType();

  this->Context = nullptr;
  this->Modified();
  // all done if assigned null
  if (!renWin)
  {
    return;
  }

  if (!this->LoadRequiredExtensions(renWin) )
  {
    vtkErrorMacro("Required OpenGL extensions not supported by the context.");
    return;
  }
  // initialize
  this->Context = renWin;
  this->Context->MakeCurrent();
}

//----------------------------------------------------------------------------
vtkOpenGLRenderWindow* vtkTextureObject::GetContext()
{
  return this->Context;
}

//----------------------------------------------------------------------------
void vtkTextureObject::DestroyTexture()
{
  // deactivate it first
  this->Deactivate();

  // because we don't hold a reference to the render
  // context we don't have any control on when it is
  // destroyed. In fact it may be destroyed before
  // we are(eg smart pointers), in which case we should
  // do nothing.
  if (this->Context && this->Handle)
  {
    GLuint tex = this->Handle;
    glDeleteTextures(1, &tex);
    vtkOpenGLCheckErrorMacro("failed at glDeleteTexture");
  }
  this->Handle = 0;
  this->NumberOfDimensions = 0;
  this->Target = 0;
  this->Components = 0;
  this->Width = this->Height = this->Depth = 0;
  this->ResetFormatAndType();
}

//----------------------------------------------------------------------------
void vtkTextureObject::CreateTexture()
{
  assert(this->Context);

  this->ResourceCallback->RegisterGraphicsResources(this->Context);

  // reuse the existing handle if we have one
  if (!this->Handle)
  {
    GLuint tex=0;
    glGenTextures(1, &tex);
    vtkOpenGLCheckErrorMacro("failed at glGenTextures");
    this->Handle=tex;

#if defined(GL_TEXTURE_BUFFER)
    if (this->Target && this->Target != GL_TEXTURE_BUFFER)
#else
    if (this->Target)
#endif
    {
      glBindTexture(this->Target, this->Handle);
      vtkOpenGLCheckErrorMacro("failed at glBindTexture");

      // See: http://www.opengl.org/wiki/Common_Mistakes#Creating_a_complete_texture
      // turn off mip map filter or set the base and max level correctly. here
      // both are done.
#ifdef GL_TEXTURE_2D_MULTISAMPLE
      if (this->Target != GL_TEXTURE_2D_MULTISAMPLE)
#endif
      {
        glTexParameteri(this->Target, GL_TEXTURE_MIN_FILTER,
                        this->GetMinificationFilterMode(this->MinificationFilter));
        glTexParameteri(this->Target, GL_TEXTURE_MAG_FILTER,
                        this->GetMagnificationFilterMode(this->MagnificationFilter));

        glTexParameteri(this->Target, GL_TEXTURE_WRAP_S,
                        this->GetWrapSMode(this->WrapS));
        glTexParameteri(this->Target, GL_TEXTURE_WRAP_T,
                        this->GetWrapTMode(this->WrapT));

#if defined(GL_TEXTURE_3D)
        if (this->Target == GL_TEXTURE_3D)
        {
          glTexParameteri(this->Target, GL_TEXTURE_WRAP_R,
                          this->GetWrapRMode(this->WrapR));
        }
#endif
      }

#ifdef GL_TEXTURE_BASE_LEVEL
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
#endif

#ifdef GL_TEXTURE_MAX_LEVEL
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
#endif

      glBindTexture(this->Target, 0);
    }
  }
}

//---------------------------------------------------------------------------
int vtkTextureObject::GetTextureUnit()
{
  if (this->Context)
  {
    return this->Context->GetTextureUnitForTexture(this);
  }
  return -1;
}

//---------------------------------------------------------------------------
void vtkTextureObject::Activate()
{
  // activate a free texture unit for this texture
  this->Context->ActivateTexture(this);
  this->Bind();
}

//---------------------------------------------------------------------------
void vtkTextureObject::Deactivate()
{
  if (this->Context)
  {
    this->Context->DeactivateTexture(this);
  }
}

//---------------------------------------------------------------------------
void vtkTextureObject::ReleaseGraphicsResources(vtkWindow *win)
{
  if (!this->ResourceCallback->IsReleasing())
  {
    this->ResourceCallback->Release();
    return;
  }

  // Ensure that the context is current before releasing any graphics
  // resources tied to it.
  if (this->Handle)
  {
    vtkOpenGLRenderWindow *rwin =
      vtkOpenGLRenderWindow::SafeDownCast(win);
    // you can commewnt out the next line to look for textures left active
    rwin->DeactivateTexture(this);
    GLuint tex = this->Handle;
    glDeleteTextures(1, &tex);
    this->Handle = 0;
    this->NumberOfDimensions = 0;
    this->Target =0;
    this->InternalFormat = 0;
    this->Format = 0;
    this->Type = 0;
    this->Components = 0;
    this->Width = this->Height = this->Depth = 0;
  }
  if (this->ShaderProgram)
  {
    this->ShaderProgram->ReleaseGraphicsResources(win);
    delete this->ShaderProgram;
    this->ShaderProgram = nullptr;
  }
}

//----------------------------------------------------------------------------
void vtkTextureObject::Bind()
{
  assert(this->Context);
  assert(this->Handle);

  glBindTexture(this->Target, this->Handle);
  vtkOpenGLCheckErrorMacro("failed at glBindTexture");

  if (this->AutoParameters && (this->GetMTime() > this->SendParametersTime))
  {
    this->SendParameters();
  }
}

//----------------------------------------------------------------------------
bool vtkTextureObject::IsBound()
{
  bool result=false;
  if(this->Context && this->Handle)
  {
    GLenum target=0; // to avoid warnings.
    switch(this->Target)
    {
#if defined(GL_TEXTURE_1D) && defined(GL_TEXTURE_BINDING_1D)
      case GL_TEXTURE_1D:
        target=GL_TEXTURE_BINDING_1D;
        break;
#endif
      case GL_TEXTURE_2D:
        target=GL_TEXTURE_BINDING_2D;
        break;
#if defined(GL_TEXTURE_2D_MULTISAMPLE) && defined(GL_TEXTURE_BINDING_2D_MULTISAMPLE)
      case  GL_TEXTURE_2D_MULTISAMPLE:
        target=GL_TEXTURE_BINDING_2D_MULTISAMPLE;
        break;
#endif
#if defined(GL_TEXTURE_3D) && defined(GL_TEXTURE_BINDING_3D)
      case GL_TEXTURE_3D:
        target=GL_TEXTURE_BINDING_3D;
        break;
#endif
#if defined(GL_TEXTURE_BUFFER) && defined(GL_TEXTURE_BINDING_BUFFER)
      case GL_TEXTURE_BUFFER:
        target=GL_TEXTURE_BINDING_BUFFER;
        break;
#endif
#if defined(GL_TEXTURE_CUBE_MAP) && defined(GL_TEXTURE_BINDING_CUBE_MAP)
      case GL_TEXTURE_CUBE_MAP:
        target=GL_TEXTURE_BINDING_CUBE_MAP;
        break;
#endif
      default:
        assert("check: impossible case" && 0);
        break;
    }
    GLint objectId;
    glGetIntegerv(target,&objectId);
    result=static_cast<GLuint>(objectId)==this->Handle;
  }
  return result;
}

//----------------------------------------------------------------------------
void vtkTextureObject::SendParameters()
{
  assert("pre: is_bound" && this->IsBound());

#if defined(GL_TEXTURE_BUFFER)
  if (this->Target == GL_TEXTURE_BUFFER)
  {
    return;
  }
#endif

#ifdef GL_TEXTURE_2D_MULTISAMPLE
  if (this->Target == GL_TEXTURE_2D_MULTISAMPLE)
  {
    return;
  }
#endif

  glTexParameteri(this->Target,GL_TEXTURE_WRAP_S, OpenGLWrap[this->WrapS]);
  glTexParameteri(this->Target,GL_TEXTURE_WRAP_T, OpenGLWrap[this->WrapT]);

#ifdef GL_TEXTURE_WRAP_R
  glTexParameteri(
        this->Target,
        GL_TEXTURE_WRAP_R,
        OpenGLWrap[this->WrapR]);
#endif

  glTexParameteri(
        this->Target,
        GL_TEXTURE_MIN_FILTER,
        OpenGLMinFilter[this->MinificationFilter]);

  glTexParameteri(
        this->Target,
        GL_TEXTURE_MAG_FILTER,
        OpenGLMagFilter[this->MagnificationFilter]);

#if GL_ES_VERSION_3_0 != 1
  glTexParameterfv(this->Target, GL_TEXTURE_BORDER_COLOR, this->BorderColor);

  if(this->DepthTextureCompare)
  {
    glTexParameteri(
          this->Target,
          GL_TEXTURE_COMPARE_MODE,
          GL_COMPARE_REF_TO_TEXTURE);
  }
  else
  {
    glTexParameteri(
          this->Target,
          GL_TEXTURE_COMPARE_MODE,
          GL_NONE);
  }
#endif

  glTexParameterf(this->Target, GL_TEXTURE_MIN_LOD, this->MinLOD);
  glTexParameterf(this->Target, GL_TEXTURE_MAX_LOD, this->MaxLOD);
  glTexParameteri(this->Target, GL_TEXTURE_BASE_LEVEL, this->BaseLevel);
  glTexParameteri(this->Target, GL_TEXTURE_MAX_LEVEL, this->MaxLevel);

  glTexParameteri(
        this->Target,
        GL_TEXTURE_COMPARE_FUNC,
        OpenGLDepthTextureCompareFunction[this->DepthTextureCompareFunction]);

  vtkOpenGLCheckErrorMacro("failed after SendParameters");
  this->SendParametersTime.Modified();
}


//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetInternalFormat(int vtktype, int numComps,
                                                 bool shaderSupportsTextureInt)
{
  if (this->InternalFormat)
  {
    return this->InternalFormat;
  }

  // pre-condition
  if(vtktype == VTK_VOID && numComps != 1)
  {
    vtkErrorMacro("Depth component texture must have 1 component only (" <<
                  numComps << " requested");
    this->InternalFormat = 0;
    return this->InternalFormat;
  }

  this->InternalFormat =
    this->GetDefaultInternalFormat(vtktype, numComps, shaderSupportsTextureInt);

  if (!this->InternalFormat)
  {
    vtkDebugMacro("Unable to find suitable internal format for T="
                  << vtktype << " NC=" << numComps << " SSTI="
                  << shaderSupportsTextureInt);
  }

  return this->InternalFormat;
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetDefaultInternalFormat(
  int vtktype, int numComps,
  bool shaderSupportsTextureInt)
{
  GLenum result = 0;

  // if shader supports int textures try that first
  if (shaderSupportsTextureInt)
  {
    result = this->Context->GetDefaultTextureInternalFormat(
      vtktype,numComps, true, false, this->UseSRGBColorSpace);
    if (!result)
    {
      vtkDebugMacro("Unsupported internal texture type!");
    }
    return result;
  }

  // try default next
  result = this->Context->GetDefaultTextureInternalFormat(
    vtktype,numComps,false,false,this->UseSRGBColorSpace);
  if (result)
  {
    return result;
  }

  // try floating point
  result = this->Context->GetDefaultTextureInternalFormat(
    vtktype,numComps,false,true,this->UseSRGBColorSpace);

  if (!result)
  {
    vtkDebugMacro("Unsupported internal texture type!");
    vtkDebugMacro("Unable to find suitable internal format for T="
      << vtktype << " NC=" << numComps << " SSTI=" << shaderSupportsTextureInt);
  }

  return result;
}


//----------------------------------------------------------------------------
void vtkTextureObject::SetInternalFormat(unsigned int glInternalFormat)
{
  if (this->InternalFormat != glInternalFormat)
  {
    this->InternalFormat = glInternalFormat;
    this->Modified();
  }
}

//----------------------------------------------------------------------------
static int vtkGetVTKType(GLenum gltype)
{
   // DON'T DEAL with VTK_CHAR as this is platform dependent.
  switch (gltype)
  {
  case GL_BYTE:
    return VTK_SIGNED_CHAR;

  case GL_UNSIGNED_BYTE:
    return VTK_UNSIGNED_CHAR;

  case GL_SHORT:
    return VTK_SHORT;

  case GL_UNSIGNED_SHORT:
    return VTK_UNSIGNED_SHORT;

  case GL_INT:
    return VTK_INT;

  case GL_UNSIGNED_INT:
    return VTK_UNSIGNED_INT;

  case GL_FLOAT:
    return VTK_FLOAT;
  }

  return 0;
}

void vtkTextureObject::GetShiftAndScale(float &shift, float &scale)
{
  shift = 1.0;
  scale = 1.0;

  // check to see if this is an int format
  GLenum iresult = this->Context->GetDefaultTextureInternalFormat(
    vtkGetVTKType(this->Type), this->Components, true, false, this->UseSRGBColorSpace);

  // using an int texture format, no shift scale
  if (iresult == this->InternalFormat)
  {
    return;
  }

  // for all float type internal formats
  switch (this->Type)
  {
    case GL_BYTE:
      scale = (VTK_SIGNED_CHAR_MAX - VTK_SIGNED_CHAR_MIN)/2.0;
      shift = scale + VTK_SIGNED_CHAR_MIN;
      break;
    case GL_UNSIGNED_BYTE:
      scale = VTK_UNSIGNED_CHAR_MAX;
      shift = 0.0;
      break;
    case GL_SHORT:
      // this may be off a tad
      scale = (VTK_SHORT_MAX - VTK_SHORT_MIN)/2.0;
      shift = scale + VTK_SHORT_MIN;
      break;
    case GL_UNSIGNED_SHORT:
      scale = VTK_UNSIGNED_SHORT_MAX;
      shift = 0.0;
      break;
    case GL_INT:
      // this may be off a tad
      scale = (1.0*VTK_INT_MAX - VTK_INT_MIN)/2.0;
      shift = scale + VTK_INT_MIN;
      break;
    case GL_UNSIGNED_INT:
      scale = VTK_UNSIGNED_INT_MAX;
      shift = 0.0;
      break;
    case GL_FLOAT:
    default:
      break;
  }
}


//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetFormat(int vtktype, int numComps,
                                         bool shaderSupportsTextureInt)
{
  if (!this->Format)
  {
    this->Format = this->GetDefaultFormat(vtktype,
      numComps, shaderSupportsTextureInt);
  }
  return this->Format;
}


//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetDefaultFormat(int vtktype, int numComps,
                                                bool shaderSupportsTextureInt)
{
  if (vtktype == VTK_VOID)
  {
    return GL_DEPTH_COMPONENT;
  }

#if GL_ES_VERSION_3_0 != 1
  if(this->SupportsTextureInteger && shaderSupportsTextureInt
     && (vtktype==VTK_SIGNED_CHAR||vtktype==VTK_UNSIGNED_CHAR||
         vtktype==VTK_SHORT||vtktype==VTK_UNSIGNED_SHORT||vtktype==VTK_INT||
       vtktype==VTK_UNSIGNED_INT))
  {
    switch (numComps)
    {
      case 1:
        return GL_RED_INTEGER;
      case 2:
        return GL_RG_INTEGER;
      case 3:
        return GL_RGB_INTEGER_EXT;
      case 4:
        return GL_RGBA_INTEGER_EXT;
    }
  }
  else
    {
    switch (numComps)
    {
      case 1:
        return GL_RED;
      case 2:
        return GL_RG;
      case 3:
        return GL_RGB;
      case 4:
        return GL_RGBA;
    }
#else
  {
    switch (numComps)
    {
#ifdef GL_RED
      case 1:
        return GL_RED;
      case 2:
        return GL_RG;
#else
      case 1:
        return GL_LUMINANCE;
      case 2:
        return GL_LUMINANCE_ALPHA;
#endif
      case 3:
        return GL_RGB;
      case 4:
        return GL_RGBA;
    }
#endif
  }
  return GL_RGB;
}

//----------------------------------------------------------------------------
void vtkTextureObject::SetFormat(unsigned int glFormat)
{
  if (this->Format != glFormat)
  {
    this->Format = glFormat;
    this->Modified();
  }
}

//----------------------------------------------------------------------------
void vtkTextureObject::ResetFormatAndType()
{
  this->Format = 0;
  this->InternalFormat = 0;
  this->Type = 0;
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetDefaultDataType(int vtk_scalar_type)
{
  // DON'T DEAL with VTK_CHAR as this is platform dependent.
  switch (vtk_scalar_type)
  {
    case VTK_SIGNED_CHAR:
      return GL_BYTE;

    case VTK_UNSIGNED_CHAR:
      return GL_UNSIGNED_BYTE;

    case VTK_SHORT:
      return GL_SHORT;

    case VTK_UNSIGNED_SHORT:
      return GL_UNSIGNED_SHORT;

    case VTK_INT:
      return GL_INT;

    case VTK_UNSIGNED_INT:
      return GL_UNSIGNED_INT;

    case VTK_FLOAT:
    case VTK_VOID: // used for depth component textures.
      return GL_FLOAT;
  }
  return 0;
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetVTKDataType()
{
  return ::vtkGetVTKType(this->Type);
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetDataType(int vtk_scalar_type)
{
  if (!this->Type)
  {
    this->Type = this->GetDefaultDataType(vtk_scalar_type);
  }

  return this->Type;
}

//----------------------------------------------------------------------------
void vtkTextureObject::SetDataType(unsigned int glType)
{
  if (this->Type != glType)
  {
    this->Type = glType;
    this->Modified();
  }
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetMinificationFilterMode(int vtktype)
{
  switch(vtktype)
  {
    case Nearest:
      return GL_NEAREST;
    case Linear:
      return GL_LINEAR;
    case NearestMipmapNearest:
      return GL_NEAREST_MIPMAP_NEAREST;
    case NearestMipmapLinear:
      return GL_NEAREST_MIPMAP_LINEAR;
    case LinearMipmapNearest:
      return GL_LINEAR_MIPMAP_NEAREST;
    case LinearMipmapLinear:
      return GL_LINEAR_MIPMAP_LINEAR;
    default:
      return GL_NEAREST;
  }
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetMagnificationFilterMode(int vtktype)
{
  switch(vtktype)
  {
    case Nearest:
      return GL_NEAREST;
    case Linear:
      return GL_LINEAR;
    default:
      return GL_NEAREST;
  }
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetWrapSMode(int vtktype)
{
  switch(vtktype)
  {
    case ClampToEdge:
      return GL_CLAMP_TO_EDGE;
    case Repeat:
      return GL_REPEAT;
#ifdef GL_CLAMP_TO_BORDER
    case ClampToBorder:
      return GL_CLAMP_TO_BORDER;
#endif
    case MirroredRepeat:
      return GL_MIRRORED_REPEAT;
    default:
      return GL_CLAMP_TO_EDGE;
  }
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetWrapTMode(int vtktype)
{
  return this->GetWrapSMode(vtktype);
}

//----------------------------------------------------------------------------
unsigned int vtkTextureObject::GetWrapRMode(int vtktype)
{
  return this->GetWrapSMode(vtktype);
}

// 1D  textures are not supported in ES 2.0 or 3.0
#if GL_ES_VERSION_3_0 != 1

//----------------------------------------------------------------------------
bool vtkTextureObject::Create1D(int numComps,
                                vtkPixelBufferObject* pbo,
                                bool shaderSupportsTextureInt)
{
  assert(this->Context);
  assert(pbo->GetContext() == this->Context.GetPointer());

  GLenum target = GL_TEXTURE_1D;

  // Now, detemine texture parameters using the information from the pbo.

  // * internalFormat depends on number of components and the data type.
  GLenum internalFormat = this->GetInternalFormat(pbo->GetType(), numComps,
                                                 shaderSupportsTextureInt);

  // * format depends on the number of components.
  GLenum format = this->GetFormat(pbo->GetType(), numComps,
                                 shaderSupportsTextureInt);

  // * type if the data type in the pbo
  GLenum type = this->GetDefaultDataType(pbo->GetType());

  if (!internalFormat || !format || !type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = target;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  pbo->Bind(vtkPixelBufferObject::UNPACKED_BUFFER);

  // Source texture data from the PBO.
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glTexImage1D(target, 0, static_cast<GLint>(internalFormat),
               static_cast<GLsizei>(pbo->GetSize()/
                                    static_cast<unsigned int>(numComps)),
               0, format,
               type, BUFFER_OFFSET(0));
  vtkOpenGLCheckErrorMacro("failed at glTexImage1D");
  pbo->UnBind();
  this->Deactivate();

  this->Target = target;
  this->Format = format;
  this->Type = type;
  this->Components = numComps;
  this->Width = pbo->GetSize();
  this->Height = 1;
  this->Depth =1;
  this->NumberOfDimensions=1;
  return true;
}

//----------------------------------------------------------------------------
bool vtkTextureObject::Create1DFromRaw(unsigned int width, int numComps,
                                       int dataType, void *data)
{
  assert(this->Context);

  // Now determine the texture parameters using the arguments.
  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to determine texture parameters.");
    return false;
  }

  GLenum target = GL_TEXTURE_1D;
  this->Target = target;
  this->Components = numComps;
  this->Width = width;
  this->Height = 1;
  this->Depth = 1;
  this->NumberOfDimensions = 1;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  glTexImage1D(this->Target,
               0,
               this->InternalFormat,
               static_cast<GLsizei> (this->Width),
               0,
               this->Format,
               this->Type,
               static_cast<const GLvoid *> (data));

  vtkOpenGLCheckErrorMacro("failed at glTexImage1D");

  this->Deactivate();
  return true;
}

// Description:
// Create a texture buffer basically a 1D texture that can be
// very large for passing data into the fragment shader
bool vtkTextureObject::CreateTextureBuffer(unsigned int numValues, int numComps,
                         int dataType, vtkOpenGLBufferObject *bo)
{
  assert(this->Context);

  // Now, detemine texture parameters using the arguments.
  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = GL_TEXTURE_BUFFER;
  this->Components = numComps;
  this->Width = numValues;
  this->Height = 1;
  this->Depth = 1;
  this->NumberOfDimensions = 1;
  this->BufferObject = bo;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  // Source texture data from the PBO.
  glTexBuffer(
      this->Target,
      this->InternalFormat,
      this->BufferObject->GetHandle());

  vtkOpenGLCheckErrorMacro("failed at glTexBuffer");

  this->Deactivate();

  return true;
}

#else

// Description:
// Create a texture buffer basically a 1D texture that can be
// very large for passing data into the fragment shader
bool vtkTextureObject::CreateTextureBuffer(unsigned int numValues, int numComps,
                         int dataType, vtkOpenGLBufferObject *bo)
{
  assert(this->Context);
  vtkErrorMacro("TextureBuffers not supported in OPenGL ES");
  // TODO: implement 1D and Texture buffers using 2D textures
  return false;
}

#endif // not ES 2.0 or 3.0

//----------------------------------------------------------------------------
bool vtkTextureObject::Create2D(unsigned int width, unsigned int height,
                                int numComps, vtkPixelBufferObject* pbo,
                                bool shaderSupportsTextureInt)
{
  assert(this->Context);
  assert(pbo->GetContext() == this->Context.GetPointer());

  if (pbo->GetSize() < width*height*static_cast<unsigned int>(numComps))
  {
    vtkErrorMacro("PBO size must match texture size.");
    return false;
  }

  // Now, detemine texture parameters using the information from the pbo.
  // * internalFormat depends on number of components and the data type.
  // * format depends on the number of components.
  // * type if the data type in the pbo

  int vtktype = pbo->GetType();
  GLenum type = this->GetDefaultDataType(vtktype);

  GLenum internalFormat
    = this->GetInternalFormat(vtktype, numComps, shaderSupportsTextureInt);

  GLenum format
    = this->GetFormat(vtktype, numComps, shaderSupportsTextureInt);

  if (!internalFormat || !format || !type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  GLenum target = GL_TEXTURE_2D;
  this->Target = target;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  // Source texture data from the PBO.
  pbo->Bind(vtkPixelBufferObject::UNPACKED_BUFFER);
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  glTexImage2D(
        target,
        0,
        internalFormat,
        static_cast<GLsizei>(width),
        static_cast<GLsizei>(height),
        0,
        format,
        type,
        BUFFER_OFFSET(0));

  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");

  pbo->UnBind();
  this->Deactivate();

  this->Target = target;
  this->Format = format;
  this->Type = type;
  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = 1;
  this->NumberOfDimensions = 2;

  return true;
}

// ----------------------------------------------------------------------------
// Description:
// Create a 2D depth texture using a PBO.
bool vtkTextureObject::CreateDepth(unsigned int width,
                                   unsigned int height,
                                   int internalFormat,
                                   vtkPixelBufferObject *pbo)
{
  assert("pre: context_exists" && this->GetContext()!=nullptr);
  assert("pre: pbo_context_exists" && pbo->GetContext()!=nullptr);
  assert("pre: context_match" && this->GetContext()==pbo->GetContext());
  assert("pre: sizes_match" && pbo->GetSize()==width*height);
  assert("pre: valid_internalFormat" && internalFormat>=0
         && internalFormat<NumberOfDepthFormats);

  GLenum inFormat=OpenGLDepthInternalFormat[internalFormat];
  GLenum type = this->GetDefaultDataType(pbo->GetType());

  this->Target=GL_TEXTURE_2D;
  this->Format=GL_DEPTH_COMPONENT;
  this->Type=type;
  this->Width=width;
  this->Height=height;
  this->Depth=1;
  this->NumberOfDimensions=2;
  this->Components=1;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  pbo->Bind(vtkPixelBufferObject::UNPACKED_BUFFER);

  // Source texture data from the PBO.
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glTexImage2D(this->Target, 0, static_cast<GLint>(inFormat),
               static_cast<GLsizei>(width), static_cast<GLsizei>(height), 0,
               this->Format, this->Type, BUFFER_OFFSET(0));
  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");
  pbo->UnBind();
  this->Deactivate();
  return true;
}

//----------------------------------------------------------------------------
bool vtkTextureObject::Create3D(unsigned int width, unsigned int height,
                                unsigned int depth, int numComps,
                                vtkPixelBufferObject* pbo,
                                bool shaderSupportsTextureInt)
{
#ifdef GL_TEXTURE_3D
  assert(this->Context);
  assert(this->Context.GetPointer() == pbo->GetContext());

  if (pbo->GetSize() != width*height*depth*static_cast<unsigned int>(numComps))
  {
    vtkErrorMacro("PBO size must match texture size.");
    return false;
  }

  GLenum target = GL_TEXTURE_3D;

  // Now, detemine texture parameters using the information from the pbo.

  // * internalFormat depends on number of components and the data type.
  GLenum internalFormat = this->GetInternalFormat(pbo->GetType(), numComps,
                                                 shaderSupportsTextureInt);

  // * format depends on the number of components.
  GLenum format = this->GetFormat(pbo->GetType(), numComps,
                                  shaderSupportsTextureInt);

  // * type if the data type in the pbo
  GLenum type = this->GetDefaultDataType(pbo->GetType());

  if (!internalFormat || !format || !type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = target;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  pbo->Bind(vtkPixelBufferObject::UNPACKED_BUFFER);

  // Source texture data from the PBO.
  glTexImage3D(target, 0, static_cast<GLint>(internalFormat),
                    static_cast<GLsizei>(width), static_cast<GLsizei>(height),
                    static_cast<GLsizei>(depth), 0, format, type,
                    BUFFER_OFFSET(0));

  vtkOpenGLCheckErrorMacro("failed at glTexImage3D");

  pbo->UnBind();
  this->Deactivate();

  this->Target = target;
  this->Format = format;
  this->Type = type;
  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = depth;
  this->NumberOfDimensions = 3;
  return true;

  #else
    return false;
  #endif
}

//----------------------------------------------------------------------------
vtkPixelBufferObject* vtkTextureObject::Download()
{
  assert(this->Context);
  assert(this->Handle);

  vtkPixelBufferObject* pbo = vtkPixelBufferObject::New();
  pbo->SetContext(this->Context);

  int vtktype = ::vtkGetVTKType(this->Type);
  if (vtktype == 0)
  {
    vtkErrorMacro("Failed to determine type.");
    return nullptr;
  }

  unsigned int size = this->Width* this->Height* this->Depth;

  // doesn't matter which Upload*D method we use since we are not really
  // uploading any data, simply allocating GPU space.
  if (!pbo->Upload1D(vtktype, nullptr, size, this->Components, 0))
  {
    vtkErrorMacro("Could not allocate memory for PBO.");
    pbo->Delete();
    return nullptr;
  }

  pbo->Bind(vtkPixelBufferObject::PACKED_BUFFER);
  this->Bind();

#if GL_ES_VERSION_3_0 != 1
  glGetTexImage(this->Target, 0, this->Format, this->Type, BUFFER_OFFSET(0));
#else
  // you can do something with glReadPixels and binding a texture as a FBO
  // I believe for ES 2.0
#endif

  vtkOpenGLCheckErrorMacro("failed at glGetTexImage");
  this->Deactivate();
  pbo->UnBind();

  pbo->SetComponents(this->Components);

  return pbo;
}

//----------------------------------------------------------------------------
bool vtkTextureObject::Create3DFromRaw(unsigned int width, unsigned int height,
                                       unsigned int depth, int numComps,
                                       int dataType, void *data)
{
  assert(this->Context);
  vtkOpenGLClearErrorMacro();

  // Now, detemine texture parameters using the arguments.
  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = GL_TEXTURE_3D;
  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = depth;
  this->NumberOfDimensions = 3;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  // Source texture data from the PBO.
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  glTexImage3D(
        this->Target,
        0,
        this->InternalFormat,
        static_cast<GLsizei>(this->Width),
        static_cast<GLsizei>(this->Height),
        static_cast<GLsizei>(this->Depth),
        0,
        this->Format,
        this->Type,
        static_cast<const GLvoid *>(data));

  this->Deactivate();

  return vtkOpenGLCheckErrors("Failed to allocate 3D texture.");
}

//----------------------------------------------------------------------------
bool vtkTextureObject::AllocateProxyTexture3D(unsigned int const width,
  unsigned int const height, unsigned int depth, int const numComps,
  int const dataType)
{
#ifndef GL_ES_VERSION_3_0
  assert(this->Context);

  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = GL_TEXTURE_3D;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  glTexImage3D(GL_PROXY_TEXTURE_3D, 0, this->InternalFormat,
    static_cast<GLsizei>(width), static_cast<GLsizei>(height),
    static_cast<GLsizei>(depth), 0, this->Format, this->Type, nullptr);

  GLsizei testWidth;
  glGetTexLevelParameteriv(GL_PROXY_TEXTURE_3D, 0, GL_TEXTURE_WIDTH,
    &testWidth);

  vtkOpenGLCheckErrorMacro("Failed after glTexImage3D with PROXY target");
  this->Deactivate();

  if (testWidth == 0)
  {
    return false;
  }
#endif
  return true;
}

//----------------------------------------------------------------------------
bool vtkTextureObject::Create2DFromRaw(unsigned int width, unsigned int height,
                                       int numComps, int dataType, void *data)
{
  assert(this->Context);

  // Now determine the texture parameters using the arguments.
  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to determine texture parameters. IF="
      << this->InternalFormat << " F=" << this->Format << " T=" << this->Type);
    return false;
  }

  GLenum target = GL_TEXTURE_2D;
  this->Target = target;
  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = 1;
  this->NumberOfDimensions = 2;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  // Source texture data from the PBO.
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  glTexImage2D(
        this->Target,
        0,
        this->InternalFormat,
        static_cast<GLsizei>(this->Width),
        static_cast<GLsizei>(this->Height),
        0,
        this->Format,
        this->Type,
        static_cast<const GLvoid *>(data));

  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");

  this->Deactivate();
  return true;
}

//----------------------------------------------------------------------------
bool vtkTextureObject::CreateCubeFromRaw(unsigned int width, unsigned int height,
                                         int numComps, int dataType, void *data[6])
{
  assert(this->Context);

  // Now determine the texture parameters using the arguments.
  this->GetDataType(dataType);
  this->GetInternalFormat(dataType, numComps, false);
  this->GetFormat(dataType, numComps, false);

  if (!this->InternalFormat || !this->Format || !this->Type)
  {
    vtkErrorMacro("Failed to determine texture parameters. IF="
      << this->InternalFormat << " F=" << this->Format << " T=" << this->Type);
    return false;
  }

  GLenum target = GL_TEXTURE_CUBE_MAP;
  this->Target = target;
  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = 1;
  this->NumberOfDimensions = 2;
  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  // Source texture data from the PBO.
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  for (int i = 0; i < 6; i++)
  {
    if (data[i])
    {
      glTexImage2D(
        GL_TEXTURE_CUBE_MAP_POSITIVE_X + i,
        0,
        this->InternalFormat,
        static_cast<GLsizei>(this->Width),
        static_cast<GLsizei>(this->Height),
        0,
        this->Format,
        this->Type,
        static_cast<const GLvoid *>(data[i]));
      vtkOpenGLCheckErrorMacro("failed at glTexImage2D");
    }
  }

  this->Deactivate();
  return true;
}

// ----------------------------------------------------------------------------
// Description:
// Create a 2D depth texture using a raw pointer.
// This is a blocking call. If you can, use PBO instead.
bool vtkTextureObject::CreateDepthFromRaw(unsigned int width,
                                          unsigned int height,
                                          int internalFormat,
                                          int rawType,
                                          void *raw)
{
  assert("pre: context_exists" && this->GetContext()!=nullptr);
  assert("pre: raw_exists" && raw!=nullptr);

  assert("pre: valid_internalFormat" && internalFormat>=0
         && internalFormat<NumberOfDepthFormats);

  // Now, detemine texture parameters using the arguments.
  this->GetDataType(rawType);

  if (!this->InternalFormat)
  {
    this->InternalFormat
      = OpenGLDepthInternalFormat[internalFormat];;
  }

  if (!this->InternalFormat || !this->Type)
  {
    vtkErrorMacro("Failed to detemine texture parameters.");
    return false;
  }

  this->Target = GL_TEXTURE_2D;
  this->Format = GL_DEPTH_COMPONENT;
  this->Width = width;
  this->Height = height;
  this->Depth = 1;
  this->NumberOfDimensions = 2;
  this->Components = 1;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glTexImage2D(this->Target, 0, static_cast<GLint>(this->InternalFormat),
               static_cast<GLsizei>(this->Width),
               static_cast<GLsizei>(this->Height), 0,
               this->Format, this->Type,raw);
  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");
  this->Deactivate();
  return true;
}

// ----------------------------------------------------------------------------
bool vtkTextureObject::AllocateDepth(unsigned int width, unsigned int height,
                                     int internalFormat)
{
  assert("pre: context_exists" && this->GetContext()!=nullptr);
  assert("pre: valid_internalFormat" && internalFormat>=0
         && internalFormat<NumberOfDepthFormats);

#ifdef GL_TEXTURE_2D_MULTISAMPLE
  this->Target =
    (this->Samples ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D);
#else
  this->Target = GL_TEXTURE_2D;
#endif

  this->Format = GL_DEPTH_COMPONENT;

  // Try to match vtk type to internal fmt
  if (!this->Type)
  {
    this->Type = OpenGLDepthInternalFormatType[internalFormat];
  }

  if (!this->InternalFormat)
  {
    this->InternalFormat = OpenGLDepthInternalFormat[internalFormat];
  }

  this->Width = width;
  this->Height = height;
  this->Depth = 1;
  this->NumberOfDimensions = 2;
  this->Components = 1;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

#ifdef GL_TEXTURE_2D_MULTISAMPLE
  if (this->Samples)
  {
    glTexImage2DMultisample(this->Target,
      this->Samples,
      static_cast<GLint>(this->InternalFormat),
      static_cast<GLsizei>(this->Width),
      static_cast<GLsizei>(this->Height),
      GL_TRUE);
  }
  else
#endif
  {
    glTexImage2D(this->Target,
      0,
      static_cast<GLint>(this->InternalFormat),
      static_cast<GLsizei>(this->Width),
      static_cast<GLsizei>(this->Height),
      0,
      this->Format,
      this->Type,
      nullptr);
  }

  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");

  this->Deactivate();
  return true;
}

// ----------------------------------------------------------------------------
bool vtkTextureObject::Allocate1D(unsigned int width, int numComps,
                                  int vtkType)
{
#ifdef GL_TEXTURE_1D
  assert(this->Context);

  this->Target = GL_TEXTURE_1D;

  this->GetDataType(vtkType);
  this->GetInternalFormat(vtkType, numComps, false);
  this->GetFormat(vtkType, numComps, false);

  this->Components = numComps;
  this->Width = width;
  this->Height = 1;
  this->Depth = 1;
  this->NumberOfDimensions = 1;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();
  glTexImage1D(this->Target, 0, static_cast<GLint>(this->InternalFormat),
               static_cast<GLsizei>(this->Width), 0, this->Format,
               this->Type,nullptr);
  vtkOpenGLCheckErrorMacro("failed at glTexImage1D");
  this->Deactivate();
  return true;
#else
  return false;
#endif
}

// ----------------------------------------------------------------------------
// Description:
// Create a 2D color texture but does not initialize its values.
// Internal format is deduced from numComps and vtkType.
bool vtkTextureObject::Allocate2D(unsigned int width,unsigned int height,
                                  int numComps, int vtkType)
{
  assert(this->Context);

#ifdef GL_TEXTURE_2D_MULTISAMPLE
  this->Target =
    (this->Samples ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D);
#else
  this->Target = GL_TEXTURE_2D;
#endif

  this->GetDataType(vtkType);
  this->GetInternalFormat(vtkType, numComps, false);
  this->GetFormat(vtkType, numComps,false);

  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth =1;
  this->NumberOfDimensions=2;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();

#ifdef GL_TEXTURE_2D_MULTISAMPLE
  if (this->Samples)
  {
    glTexImage2DMultisample(this->Target,
      this->Samples,
      static_cast<GLint>(this->InternalFormat),
      static_cast<GLsizei>(this->Width),
      static_cast<GLsizei>(this->Height),
      GL_TRUE);
  }
  else
#endif
  {
    glTexImage2D(this->Target,
      0,
      static_cast<GLint>(this->InternalFormat),
      static_cast<GLsizei>(this->Width),
      static_cast<GLsizei>(this->Height),
      0,
      this->Format,
      this->Type,
      nullptr);
  }
  vtkOpenGLCheckErrorMacro("failed at glTexImage2D");
  this->Deactivate();
  return true;
}

// ----------------------------------------------------------------------------
// Description:
// Create a 3D color texture but does not initialize its values.
// Internal format is deduced from numComps and vtkType.
bool vtkTextureObject::Allocate3D(unsigned int width,unsigned int height,
                                  unsigned int depth, int numComps,
                                  int vtkType)
{
#ifdef GL_TEXTURE_3D
  this->Target=GL_TEXTURE_3D;

  if(this->Context==nullptr)
  {
    vtkErrorMacro("No context specified. Cannot create texture.");
    return false;
  }

  this->GetInternalFormat(vtkType, numComps, false);
  this->GetFormat(vtkType, numComps, false);
  this->GetDataType(vtkType);

  this->Components = numComps;
  this->Width = width;
  this->Height = height;
  this->Depth = depth;
  this->NumberOfDimensions = 3;

  this->Context->ActivateTexture(this);
  this->CreateTexture();
  this->Bind();
  glTexImage3D(this->Target, 0,
               static_cast<GLint>(this->InternalFormat),
               static_cast<GLsizei>(this->Width),
               static_cast<GLsizei>(this->Height),
               static_cast<GLsizei>(this->Depth), 0,
               this->Format, this->Type, nullptr);
  vtkOpenGLCheckErrorMacro("failed at glTexImage3D");
  this->Deactivate();
  return true;
#else
  return false;
#endif
}

// ----------------------------------------------------------------------------
void vtkTextureObject::CopyToFrameBuffer(
  vtkShaderProgram *program, vtkOpenGLVertexArrayObject *vao)
{
  // the following math really only works when texture
  // and viewport are of the same dimensions
  float minXTexCoord=static_cast<float>(
    static_cast<double>(0.5)/this->Width);
  float minYTexCoord=static_cast<float>(
    static_cast<double>(0.5)/this->Height);

  float maxXTexCoord=static_cast<float>(
    static_cast<double>(this->Width-0.5)/this->Width);
  float maxYTexCoord=static_cast<float>(
    static_cast<double>(this->Height-0.5)/this->Height);

  float tcoords[] = {
    minXTexCoord, minYTexCoord,
    maxXTexCoord, minYTexCoord,
    maxXTexCoord, maxYTexCoord,
    minXTexCoord, maxYTexCoord};

  float verts[] = {
    -1.0f, -1.0f, 0.0f,
    1.0f, -1.0f, 0.0f,
    1.0f, 1.0f, 0.0f,
    -1.0f, 1.0f, 0.0f};

    this->CopyToFrameBuffer(tcoords, verts, program, vao);
}

// ----------------------------------------------------------------------------
void vtkTextureObject::CopyToFrameBuffer(
  int srcXmin, int srcYmin,
  int srcXmax, int srcYmax,
  int dstXmin, int dstYmin,
  int dstSizeX, int dstSizeY,
  vtkShaderProgram *program, vtkOpenGLVertexArrayObject *vao)
{
  float dstXmax = static_cast<float>(dstXmin+srcXmax-srcXmin);
  float dstYmax = static_cast<float>(dstYmin+srcYmax-srcYmin);

  this->CopyToFrameBuffer(srcXmin, srcYmin, srcXmax, srcYmax,
    dstXmin, dstYmin, dstXmax, dstYmax, dstSizeX, dstSizeY,
    program, vao);
}

// ----------------------------------------------------------------------------
void vtkTextureObject::CopyToFrameBuffer(
  int srcXmin, int srcYmin,
  int srcXmax, int srcYmax,
  int dstXmin, int dstYmin,
  int dstXmax, int dstYmax,
  int vtkNotUsed(dstSizeX), int vtkNotUsed(dstSizeY),
  vtkShaderProgram *program, vtkOpenGLVertexArrayObject *vao)
{
  assert("pre: positive_srcXmin" && srcXmin>=0);
  assert("pre: max_srcXmax" &&
         static_cast<unsigned int>(srcXmax)<this->GetWidth());
  assert("pre: increasing_x" && srcXmin<=srcXmax);
  assert("pre: positive_srcYmin" && srcYmin>=0);
  assert("pre: max_srcYmax" &&
         static_cast<unsigned int>(srcYmax)<this->GetHeight());
  assert("pre: increasing_y" && srcYmin<=srcYmax);
  assert("pre: positive_dstXmin" && dstXmin>=0);
  assert("pre: positive_dstYmin" && dstYmin>=0);

  float minXTexCoord=static_cast<float>(
    static_cast<double>(srcXmin+0.5)/this->Width);
  float minYTexCoord=static_cast<float>(
    static_cast<double>(srcYmin+0.5)/this->Height);

  float maxXTexCoord=static_cast<float>(
    static_cast<double>(srcXmax+0.5)/this->Width);
  float maxYTexCoord=static_cast<float>(
    static_cast<double>(srcYmax+0.5)/this->Height);

  GLint saved_viewport[4];
  glGetIntegerv(GL_VIEWPORT, saved_viewport);
  glViewport(dstXmin, dstYmin, dstXmax - dstXmin + 1, dstYmax - dstYmin + 1);

  float tcoords[] = {
    minXTexCoord, minYTexCoord,
    maxXTexCoord, minYTexCoord,
    maxXTexCoord, maxYTexCoord,
    minXTexCoord, maxYTexCoord};

  float verts[] = {
    -1.f, -1.f, 0.0f,
    1.0f, -1.f, 0.0f,
    1.0f, 1.0f, 0.0f,
    -1.f, 1.0f, 0.0f};

    this->CopyToFrameBuffer(tcoords, verts, program, vao);

    glViewport(saved_viewport[0], saved_viewport[1], saved_viewport[2],
      saved_viewport[3]);
}

void vtkTextureObject::CopyToFrameBuffer(float *tcoords, float *verts,
  vtkShaderProgram *program, vtkOpenGLVertexArrayObject *vao)
{
  vtkOpenGLClearErrorMacro();

  // if no program or VAO was provided, then use
  // a simple pass through program and bind this
  // texture to it
  if (!program || !vao)
  {
    if (!this->ShaderProgram)
    {
      this->ShaderProgram = new vtkOpenGLHelper;

      // build the shader source code
      std::string VSSource = vtkTextureObjectVS;
      std::string FSSource = vtkTextureObjectFS;
      std::string GSSource;

      // compile and bind it if needed
      vtkShaderProgram *newShader =
        this->Context->GetShaderCache()->ReadyShaderProgram(
          VSSource.c_str(),
          FSSource.c_str(),
          GSSource.c_str());

      // if the shader changed reinitialize the VAO
      if (newShader != this->ShaderProgram->Program)
      {
        this->ShaderProgram->Program = newShader;
        this->ShaderProgram->VAO->ShaderProgramChanged(); // reset the VAO as the shader has changed
      }

      this->ShaderProgram->ShaderSourceTime.Modified();
    }
    else
    {
      this->Context->GetShaderCache()->ReadyShaderProgram(
        this->ShaderProgram->Program);
    }

    if (this->ShaderProgram->Program)
    {
      // bind and activate this texture
      this->Activate();
      int sourceId = this->GetTextureUnit();
      this->ShaderProgram->Program->SetUniformi("source",sourceId);
      vtkOpenGLRenderUtilities::RenderQuad(verts, tcoords, this->ShaderProgram->Program,
        this->ShaderProgram->VAO);
      this->Deactivate();
    }
  }
  else
  {
    vtkOpenGLRenderUtilities::RenderQuad(verts, tcoords, program, vao);
  }

  vtkOpenGLCheckErrorMacro("failed after CopyToFrameBuffer")
}

//----------------------------------------------------------------------------
// Description:
// Copy a sub-part of a logical buffer of the framebuffer (color or depth)
// to the texture object. src is the framebuffer, dst is the texture.
// (srcXmin,srcYmin) is the location of the lower left corner of the
// rectangle in the framebuffer. (dstXmin,dstYmin) is the location of the
// lower left corner of the rectangle in the texture. width and height
// specifies the size of the rectangle in pixels.
// If the logical buffer is a color buffer, it has to be selected first with
// glReadBuffer().
// \pre is2D: GetNumberOfDimensions()==2
void vtkTextureObject::CopyFromFrameBuffer(int srcXmin,
                                           int srcYmin,
                                           int vtkNotUsed(dstXmin),
                                           int vtkNotUsed(dstYmin),
                                           int width,
                                           int height)
{
  assert("pre: is2D" && this->GetNumberOfDimensions()==2);

  this->Activate();
  glCopyTexImage2D(this->Target,0,this->Format,srcXmin,srcYmin,width,height,0);
  vtkOpenGLCheckErrorMacro("failed at glCopyTexImage2D " << this->Format);
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetMaximumTextureSize(vtkOpenGLRenderWindow* context)
{
  GLint maxSize = -1;
  if (context && context->IsCurrent())
  {
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxSize);
  }

  return static_cast<int>(maxSize);
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetMaximumTextureSize3D(vtkOpenGLRenderWindow* context)
{
  GLint maxSize = -1;
  if (context && context->IsCurrent())
  {
    glGetIntegerv(GL_MAX_3D_TEXTURE_SIZE, &maxSize);
  }

  return static_cast<int>(maxSize);
}

//----------------------------------------------------------------------------
int vtkTextureObject::GetMaximumTextureSize3D()
{
  assert("Context == NULL" && this->Context);
  return vtkTextureObject::GetMaximumTextureSize3D(this->Context);
}

//----------------------------------------------------------------------------
void vtkTextureObject::Resize(unsigned int width, unsigned int height)
{
  if (this->Width == width && this->Height == height)
  {
    return;
  }

  this->Width = width;
  this->Height = height;

  this->Context->ActivateTexture(this);
  this->Bind();

  if (this->NumberOfDimensions== 2)
  {
#ifdef GL_TEXTURE_2D_MULTISAMPLE
    if (this->Samples)
    {
      glTexImage2DMultisample( this->Target, this->Samples,
        static_cast<GLint>(this->InternalFormat),
        static_cast<GLsizei>(this->Width),
        static_cast<GLsizei>(this->Height),
        GL_TRUE);
    }
    else
#endif
    {
      glTexImage2D(this->Target, 0, static_cast<GLint>(this->InternalFormat),
                 static_cast<GLsizei>(this->Width),
                 static_cast<GLsizei>(this->Height),
                 0, this->Format, this->Type, nullptr);
    }
  }
  else if (this->NumberOfDimensions== 3)
  {
    glTexImage3D(this->Target, 0,
               static_cast<GLint>(this->InternalFormat),
               static_cast<GLsizei>(this->Width),
               static_cast<GLsizei>(this->Height),
               static_cast<GLsizei>(this->Depth), 0,
               this->Format, this->Type, nullptr);
  }
#ifdef GL_TEXTURE_1D
  else if (this->NumberOfDimensions == 1)
  {
    glTexImage1D(this->Target, 0, static_cast<GLint>(this->InternalFormat),
               static_cast<GLsizei>(this->Width), 0, this->Format,
               this->Type,nullptr);
  }
#endif

  vtkOpenGLCheckErrorMacro("failed at texture resize");
  this->Deactivate();
}

//----------------------------------------------------------------------------
void vtkTextureObject::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);

  os << indent << "Width: " << this->Width << endl;
  os << indent << "Height: " << this->Height << endl;
  os << indent << "Depth: " << this->Depth << endl;
  os << indent << "Components: " << this->Components << endl;
  os << indent << "Handle: " << this->Handle << endl;
  os << indent << "Target: ";

  switch(this->Target)
  {
#ifdef GL_TEXTURE_1D
    case GL_TEXTURE_1D:
      os << "GL_TEXTURE_1D" << endl;
      break;
#endif
    case  GL_TEXTURE_2D:
      os << "GL_TEXTURE_2D" << endl;
      break;
#ifdef GL_TEXTURE_3D
    case  GL_TEXTURE_3D:
      os << "GL_TEXTURE_3D" << endl;
      break;
#endif
    default:
      os << "unknown value: 0x" << hex << this->Target << dec <<endl;
      break;
  }

  os << indent << "NumberOfDimensions: " << this->NumberOfDimensions << endl;

  os << indent << "Format: " << this->Format << endl;
  os << indent << "InternalFormat: " << this->InternalFormat << endl;
  os << indent << "Type: " << this->Type << endl;

  os << indent << "WrapS: " << WrapAsString[this->WrapS] << endl;
  os << indent << "WrapT: " << WrapAsString[this->WrapT] << endl;
  os << indent << "WrapR: " << WrapAsString[this->WrapR] << endl;

  os << indent << "MinificationFilter: "
     << MinMagFilterAsString[this->MinificationFilter] << endl;

  os << indent << "MagnificationFilter: "
     << MinMagFilterAsString[this->MagnificationFilter] << endl;

  os << indent << "MinLOD: " << this->MinLOD << endl;
  os << indent << "MaxLOD: " << this->MaxLOD << endl;
  os << indent << "BaseLevel: " << this->BaseLevel << endl;
  os << indent << "MaxLevel: " << this->MaxLevel << endl;
  os << indent << "DepthTextureCompare: " << this->DepthTextureCompare
     << endl;
  os << indent << "DepthTextureCompareFunction: "
     << DepthTextureCompareFunctionAsString[this->DepthTextureCompareFunction]
     << endl;
  os << indent << "GenerateMipmap: " << this->GenerateMipmap << endl;
}
