Add a mechanism where shader uniforms can be updates

Added an event that fires when the shader updsates so that
programs can use it to update any uniforms they want to

Common/Core/vtkCommand.h

@@ -194,6 +194,8 @@
 //  - A int* being the number of the button
 // - vtkCommand::TDxButtonReleaseEvent
 //  - A int* being the number of the button
+// - vtkCommand::UpdateShaderEvent
+//  - A vtkOpenGLHelper* currently being used
 //
 // .SECTION See Also
 // vtkObject vtkCallbackCommand vtkOldStyleCallbackCommand
@@ -309,6 +311,7 @@
     _vtk_add_event(WindowSupportsOpenGLEvent)\
     _vtk_add_event(WindowIsDirectEvent)\
     _vtk_add_event(UncheckedPropertyModifiedEvent)\
+    _vtk_add_event(UpdateShaderEvent)\
     _vtk_add_event(MessageEvent)
 
 #define vtkEventDeclarationMacro(_enum_name)\

Rendering/OpenGL2/Testing/Cxx/TestUserShader2.cxx

@@ -12,20 +12,74 @@
 
 =========================================================================*/
 
-#include "vtkCamera.h"
-#include "vtkRenderer.h"
-#include "vtkRenderWindow.h"
 #include "vtkActor.h"
+#include "vtkCamera.h"
+#include "vtkCommand.h"
+#include "vtkMath.h"
+#include "vtkNew.h"
 #include "vtkOpenGLPolyDataMapper.h"
 #include "vtkPLYReader.h"
-#include "vtkNew.h"
-#include "vtkProperty.h"
 #include "vtkPolyDataNormals.h"
-
+#include "vtkProperty.h"
 #include "vtkRegressionTestImage.h"
+#include "vtkRenderWindow.h"
+#include "vtkRenderWindowInteractor.h"
+#include "vtkRenderer.h"
+#include "vtkShaderProgram.h"
 #include "vtkTestUtilities.h"
+#include "vtkTimerLog.h"
 
-#include "vtkRenderWindowInteractor.h"
+
+#define VTK_CREATE(type, name) \
+  vtkSmartPointer<type> name = vtkSmartPointer<type>::New()
+
+// -----------------------------------------------------------------------
+// Update a uniform in the shader for each render. We do this with a
+// callback for the UpdateShaderEvent
+class vtkShaderCallback : public vtkCommand
+{
+public:
+  static vtkShaderCallback *New()
+    { return new vtkShaderCallback; }
+  vtkRenderer *Renderer;
+  virtual void Execute(vtkObject *, unsigned long, void*cbo)
+    {
+    vtkOpenGLHelper *cellBO = reinterpret_cast<vtkOpenGLHelper*>(cbo);
+
+    float diffuseColor[3];
+
+#if 0  // trippy mode
+    float inputHSV[3];
+    double theTime = vtkTimerLog::GetUniversalTime();
+    double twopi = 2.0*3.1415926;
+
+    inputHSV[0] = sin(twopi*fmod(theTime,3.0)/3.0)/4.0 + 0.25;
+    inputHSV[1] = sin(twopi*fmod(theTime,4.0)/4.0)/2.0 + 0.5;
+    inputHSV[2] = 0.7*(sin(twopi*fmod(theTime,19.0)/19.0)/2.0 + 0.5);
+    vtkMath::HSVToRGB(inputHSV,diffuseColor);
+    cellBO->Program->SetUniform3f("diffuseColorUniform", diffuseColor);
+
+    inputHSV[0] = sin(twopi*fmod(theTime,5.0)/5.0)/4.0 + 0.75;
+    inputHSV[1] = sin(twopi*fmod(theTime,7.0)/7.0)/2.0 + 0.5;
+    inputHSV[2] = 0.5*(sin(twopi*fmod(theTime,17.0)/17.0)/2.0 + 0.5);
+    vtkMath::HSVToRGB(inputHSV,diffuseColor);
+    this->Renderer->SetBackground(diffuseColor[0], diffuseColor[1], diffuseColor[2]);
+
+    inputHSV[0] = sin(twopi*fmod(theTime,11.0)/11.0)/2.0+0.5;
+    inputHSV[1] = sin(twopi*fmod(theTime,13.0)/13.0)/2.0 + 0.5;
+    inputHSV[2] = 0.5*(sin(twopi*fmod(theTime,17.0)/17.0)/2.0 + 0.5);
+    vtkMath::HSVToRGB(inputHSV,diffuseColor);
+    this->Renderer->SetBackground2(diffuseColor[0], diffuseColor[1], diffuseColor[2]);
+#else
+    diffuseColor[0] = 0.4;
+    diffuseColor[1] = 0.7;
+    diffuseColor[2] = 0.6;
+    cellBO->Program->SetUniform3f("diffuseColorUniform", diffuseColor);
+#endif
+    }
+
+  vtkShaderCallback() {}
+};
 
 //----------------------------------------------------------------------------
 int TestUserShader2(int argc, char *argv[])
@@ -38,6 +92,7 @@ int TestUserShader2(int argc, char *argv[])
   renderWindow->SetSize(400, 400);
   renderWindow->AddRenderer(renderer.Get());
   renderer->AddActor(actor.Get());
+  renderer->GradientBackgroundOn();
   vtkNew<vtkRenderWindowInteractor>  iren;
   iren->SetRenderWindow(renderWindow.Get());
 
@@ -62,11 +117,12 @@ int TestUserShader2(int argc, char *argv[])
   actor->GetProperty()->SetSpecularPower(20.0);
   actor->GetProperty()->SetOpacity(1.0);
 
-  // Use our own hardcoded shader code. Generally this is a bad idea as there
-  // are so many things VTK supports that hardcoded shaders will not handle
-  // depth peeling, picking, etc, but if you really want to, here is an example.
-  // The mapper will set a bunch of uniforms regardless of if you are using
-  // them. But feel free to use them :-)
+  // Use our own hardcoded shader code. Generally this is a bad idea in a
+  // general purpose program as there are so many things VTK supports that
+  // hardcoded shaders will not handle depth peeling, picking, etc, but if you
+  // know what your data will be like it can be very useful. The mapper will set
+  // a bunch of uniforms regardless of if you are using them. But feel free to
+  // use them :-)
   mapper->SetVertexShaderCode(
     "//VTK::System::Dec\n"  // always start with this line
     "attribute vec4 vertexMC;\n"
@@ -88,15 +144,21 @@ int TestUserShader2(int argc, char *argv[])
     "//VTK::System::Dec\n"  // always start with this line
     "//VTK::Output::Dec\n"  // always have this line in your FS
     "varying vec3 normalVCVSOutput;\n"
+    "uniform vec3 diffuseColorUniform;\n"
     "void main () {\n"
     "  float df = max(0.0, normalVCVSOutput.z);\n"
     "  float sf = pow(df, 20.0);\n"
-    "  vec3 diffuse = df * vec3(0.4,0.9,0.7);\n"
+    "  vec3 diffuse = df * diffuseColorUniform;\n"
     "  vec3 specular = sf * vec3(0.4,0.4,0.4);\n"
-    "  gl_FragData[0] = vec4(diffuse + specular, 1.0);\n"
+    "  gl_FragData[0] = vec4(0.3*abs(normalVCVSOutput) + 0.7*diffuse + specular, 1.0);\n"
     "}\n"
     );
 
+  // Setup a callback to change some uniforms
+  VTK_CREATE(vtkShaderCallback, myCallback);
+  myCallback->Renderer = renderer.Get();
+  mapper->AddObserver(vtkCommand::UpdateShaderEvent,myCallback);
+
   renderWindow->Render();
   renderer->GetActiveCamera()->SetPosition(-0.2,0.4,1);
   renderer->GetActiveCamera()->SetFocalPoint(0,0,0);

Rendering/OpenGL2/Testing/Data/Baseline/TestUserShader2.png.md5

-7b26fde777b26b1ee5c67b26d3c76e7e
+3fb7549af8fdf86d30e35e783d1348e5

Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx

@@ -1390,6 +1390,9 @@ void vtkOpenGLPolyDataMapper::UpdateShaders(
   this->SetCameraShaderParameters(cellBO, ren, actor);
   this->SetLightingShaderParameters(cellBO, ren, actor);
 
+  // allow the program to set what it wants
+  this->InvokeEvent(vtkCommand::UpdateShaderEvent,&cellBO);
+
   vtkOpenGLCheckErrorMacro("failed after UpdateShader");
 }