0028180: Visualization, TKOpenGl - Performance of Shaded presentation dropped due to FFP disabled by default

FFP state management (light sources, matrices, clipping planes) has been
moved to OpenGl_ShaderManager for consistency with Programmable Pipeline.

OpenGl_Context::BindProgram() does not re-bind already active Program.
OpenGl_PrimitiveArray::Render() does not reset active Program at the end.

OpenGl_Context::ApplyModelViewMatrix() now checks if matrix differs
from already set one before modifying state in Shader Manager.
This allows avoing redundant state changes, matrix uploads onto GPU
and re-computation of inversed matrices.

NCollection_Mat4 has been extended with equality check operators for proper comparison.

OpenGl_ShaderManager - the tracking Material state has been added.
Removed unreachable states OPENGL_NS_RESMAT, OPENGL_NS_TEXTURE and OPENGL_NS_WHITEBACK.

Fixed resetting FFP material state after displaying GL_COLOR_ARRAY vertices;
the Material state within Shader Manager is now
invalidated within OpenGl_VertexBuffer::unbindFixedColor().

OpenGl_Workspace::ApplyAspectFace() - fixed invalidating Material State
when only Highlighting style is changing.

src/ViewerTest/ViewerTest_OpenGlCommands.cxx

@@ -30,6 +30,7 @@
 #include <OpenGl_Element.hxx>
 #include <OpenGl_GlCore20.hxx>
 #include <OpenGl_GraphicDriver.hxx>
+#include <OpenGl_ShaderManager.hxx>
 #include <OpenGl_Workspace.hxx>
 #include <OSD_Environment.hxx>
 #include <OSD_File.hxx>
@@ -156,7 +157,8 @@ void VUserDrawObj::Render(const Handle(OpenGl_Workspace)& theWorkspace) const
 {
   // this sample does not use GLSL programs - make sure it is disabled
   Handle(OpenGl_Context) aCtx = theWorkspace->GetGlContext();
-  aCtx->BindProgram (NULL);
+  aCtx->BindProgram (Handle(OpenGl_ShaderProgram)());
+  aCtx->ShaderManager()->PushState (Handle(OpenGl_ShaderProgram)());
 
   // To test linking against OpenGl_Workspace and all aspect classes
   const OpenGl_AspectMarker* aMA = theWorkspace->AspectMarker();