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

Program:   Visualization Toolkit
Module:    vtkOpenVRModel.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 "vtkOpenVRModel.h"

#include "vtkInteractorObserver.h"
#include "vtkMatrix4x4.h"
#include "vtkObjectFactory.h"
#include "vtkOpenGLHelper.h"
#include "vtkOpenGLIndexBufferObject.h"
#include "vtkOpenGLShaderCache.h"
#include "vtkOpenGLState.h"
#include "vtkOpenGLVertexArrayObject.h"
#include "vtkOpenGLVertexBufferObject.h"
#include "vtkOpenVRCamera.h"
#include "vtkOpenVRRay.h"
#include "vtkOpenVRRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkRendererCollection.h"
#include "vtkShaderProgram.h"
#include "vtkTextureObject.h"

/*=========================================================================
vtkOpenVRModel
=========================================================================*/
vtkStandardNewMacro(vtkOpenVRModel);

vtkOpenVRModel::vtkOpenVRModel()
{
  this->RawModel = nullptr;
  this->RawTexture = nullptr;
  this->Loaded = false;
  this->ModelVBO = vtkOpenGLVertexBufferObject::New();
  this->FailedToLoad = false;
  this->TrackedDevice = vr::k_unTrackedDeviceIndexInvalid;
};

vtkOpenVRModel::~vtkOpenVRModel()
{
  this->ModelVBO->Delete();
  this->ModelVBO = 0;
}

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

  os << indent << "Loaded " << (this->Loaded ? "On\n" : "Off\n");
}

void vtkOpenVRModel::ReleaseGraphicsResources(vtkRenderWindow* win)
{
  this->ModelVBO->ReleaseGraphicsResources();
  this->ModelHelper.ReleaseGraphicsResources(win);
  this->TextureObject->ReleaseGraphicsResources(win);
}

bool vtkOpenVRModel::Build(vtkOpenVRRenderWindow* win)
{
  this->ModelVBO->Upload(
    this->RawModel->rVertexData, this->RawModel->unVertexCount, vtkOpenGLBufferObject::ArrayBuffer);

  this->ModelHelper.IBO->Upload(this->RawModel->rIndexData, this->RawModel->unTriangleCount * 3,
    vtkOpenGLBufferObject::ElementArrayBuffer);
  this->ModelHelper.IBO->IndexCount = this->RawModel->unTriangleCount * 3;

  this->ModelHelper.Program = win->GetShaderCache()->ReadyShaderProgram(

    // vertex shader -- use normals?? yes?
    "//VTK::System::Dec\n"
    "uniform mat4 matrix;\n"
    "in vec4 position;\n"
    //    "attribute vec3 v3NormalIn;\n"
    "in vec2 v2TexCoordsIn;\n"
    "out vec2 v2TexCoord;\n"
    "void main()\n"
    "{\n"
    " v2TexCoord = v2TexCoordsIn;\n"
    " gl_Position = matrix * vec4(position.xyz, 1);\n"
    "}\n",

    // fragment shader
    "//VTK::System::Dec\n"
    "//VTK::Output::Dec\n"
    "uniform sampler2D diffuse;\n"
    "in vec2 v2TexCoord;\n"
    "out vec4 outputColor;\n"
    "void main()\n"
    "{\n"
    "  gl_FragData[0] = texture(diffuse, v2TexCoord);\n"
    "}\n",

    // geom shader
    "");

  vtkShaderProgram* program = this->ModelHelper.Program;
  this->ModelHelper.VAO->Bind();
  if (!this->ModelHelper.VAO->AddAttributeArray(program, this->ModelVBO, "position",
        offsetof(vr::RenderModel_Vertex_t, vPosition), sizeof(vr::RenderModel_Vertex_t), VTK_FLOAT,
        3, false))
  {
    vtkErrorMacro(<< "Error setting position in shader VAO.");
  }
  if (!this->ModelHelper.VAO->AddAttributeArray(program, this->ModelVBO, "v2TexCoordsIn",
        offsetof(vr::RenderModel_Vertex_t, rfTextureCoord), sizeof(vr::RenderModel_Vertex_t),
        VTK_FLOAT, 2, false))
  {
    vtkErrorMacro(<< "Error setting tcoords in shader VAO.");
  }

  // create and populate the texture
  this->TextureObject->SetContext(win);
  this->TextureObject->Create2DFromRaw(this->RawTexture->unWidth, this->RawTexture->unHeight, 4,
    VTK_UNSIGNED_CHAR,
    const_cast<void*>(static_cast<const void* const>(this->RawTexture->rubTextureMapData)));
  this->TextureObject->SetWrapS(vtkTextureObject::ClampToEdge);
  this->TextureObject->SetWrapT(vtkTextureObject::ClampToEdge);

  this->TextureObject->SetMinificationFilter(vtkTextureObject::LinearMipmapLinear);
  this->TextureObject->SetGenerateMipmap(true);

  return true;
}

void vtkOpenVRModel::Render(vtkOpenVRRenderWindow* win, const vr::TrackedDevicePose_t& pose)
{
  if (this->FailedToLoad)
  {
    return;
  }

  // do we not have the model loaded? Keep trying it is async
  if (!this->RawModel)
  {
    // start loading the model if we didn't find one
    vr::EVRRenderModelError result =
      vr::VRRenderModels()->LoadRenderModel_Async(this->GetName().c_str(), &this->RawModel);
    if (result > vr::EVRRenderModelError::VRRenderModelError_Loading)
    {
      this->FailedToLoad = true;
      if (result != vr::VRRenderModelError_NotEnoughTexCoords)
      {
        vtkErrorMacro(
          "Unable to load render model " << this->GetName() << " with error code " << result);
      }
      return; // move on to the next tracked device
    }
  }

  // if we have the model try loading the texture
  if (this->RawModel && !this->RawTexture)
  {
    if (vr::VRRenderModels()->LoadTexture_Async(this->RawModel->diffuseTextureId,
          &this->RawTexture) > vr::EVRRenderModelError::VRRenderModelError_Loading)
    {
      vtkErrorMacro(<< "Unable to load render texture for render model " << this->GetName());
    }

    // if this call succeeded and we have the texture
    // then build the VTK structures
    if (this->RawTexture)
    {
      if (!this->Build(win))
      {
        vtkErrorMacro("Unable to create GL model from render model " << this->GetName());
      }
      vr::VRRenderModels()->FreeRenderModel(this->RawModel);
      vr::VRRenderModels()->FreeTexture(this->RawTexture);
      this->Loaded = true;
    }
  }

  if (this->Loaded)
  {
    // render the model
    win->GetState()->vtkglDepthMask(GL_TRUE);
    win->GetShaderCache()->ReadyShaderProgram(this->ModelHelper.Program);
    this->ModelHelper.VAO->Bind();
    this->ModelHelper.IBO->Bind();

    this->TextureObject->Activate();
    this->ModelHelper.Program->SetUniformi("diffuse", this->TextureObject->GetTextureUnit());

    vtkRenderer* ren = static_cast<vtkRenderer*>(win->GetRenderers()->GetItemAsObject(0));
    if (ren)
    {
      vtkOpenVRCamera* cam = static_cast<vtkOpenVRCamera*>(ren->GetActiveCamera());

      double elems[16];
      for (int j = 0; j < 3; j++)
      {
        for (int i = 0; i < 4; i++)
        {
          elems[j + i * 4] = pose.mDeviceToAbsoluteTracking.m[j][i];
        }
      }
      elems[3] = 0.0;
      elems[7] = 0.0;
      elems[11] = 0.0;
      elems[15] = 1.0;

      vtkMatrix4x4* tcdc;
      cam->GetTrackingToDCMatrix(tcdc);

      vtkMatrix4x4::Multiply4x4(
        elems, (double*)(tcdc->Element), (double*)(this->PoseMatrix->Element));

      this->ModelHelper.Program->SetUniformMatrix("matrix", this->PoseMatrix);
    }

    glDrawElements(
      GL_TRIANGLES, static_cast<GLsizei>(this->ModelHelper.IBO->IndexCount), GL_UNSIGNED_SHORT, 0);
    this->TextureObject->Deactivate();

    // Draw ray
    if (this->Ray->GetShow())
    {
      this->Ray->Render(win, this->PoseMatrix);
    }
  }
}

void vtkOpenVRModel::SetShowRay(bool v)
{
  this->Ray->SetShow(v);
}

void vtkOpenVRModel::SetRayLength(double length)
{
  this->Ray->SetLength(length);
}
