Comment some (vertex) texture lookup functionality.

src/common/version.h

 #define MAJOR_VERSION 0
 #define MINOR_VERSION 0
 #define BUILD_VERSION 0
-#define BUILD_REVISION 642
+#define BUILD_REVISION 643
 
 #define STRINGIFY(x) #x
 #define MACRO_STRINGIFY(x) STRINGIFY(x)

src/libGLESv2/Context.cpp

@@ -2017,16 +2017,19 @@ void Context::applyTextures()
     }
 }
 
+// For each Direct3D 9 sampler of either the pixel or vertex stage,
+// looks up the corresponding OpenGL texture image unit and texture type,
+// and sets the texture and its addressing/filtering state (or NULL when inactive).
 void Context::applyTextures(SamplerType type)
 {
     IDirect3DDevice9 *device = getDevice();
     Program *programObject = getCurrentProgram();
 
-    int samplerCount = (type == SAMPLER_PIXEL) ? MAX_TEXTURE_IMAGE_UNITS : MAX_VERTEX_TEXTURE_IMAGE_UNITS_VTF;
+    int samplerCount = (type == SAMPLER_PIXEL) ? MAX_TEXTURE_IMAGE_UNITS : MAX_VERTEX_TEXTURE_IMAGE_UNITS_VTF;   // Range of Direct3D 9 samplers of given sampler type
 
     for (int samplerIndex = 0; samplerIndex < samplerCount; samplerIndex++)
     {
-        int textureUnit = programObject->getSamplerMapping(type, samplerIndex);
+        int textureUnit = programObject->getSamplerMapping(type, samplerIndex);   // OpenGL texture image unit index
         int d3dSampler = (type == SAMPLER_PIXEL) ? samplerIndex : D3DVERTEXTEXTURESAMPLER0 + samplerIndex;
         unsigned int *appliedTextureSerial = (type == SAMPLER_PIXEL) ? mAppliedTextureSerialPS : mAppliedTextureSerialVS;
 

src/libGLESv2/Program.cpp

@@ -191,8 +191,8 @@ int Program::getSemanticIndex(int attributeIndex)
     return mSemanticIndex[attributeIndex];
 }
 
-// Returns the index of the texture unit corresponding to a Direct3D 9 sampler
-// index referenced in the compiled HLSL shader
+// Returns the index of the texture image unit (0-19) corresponding to a Direct3D 9 sampler
+// index (0-15 for the pixel shader and 0-3 for the vertex shader).
 GLint Program::getSamplerMapping(SamplerType type, unsigned int samplerIndex)
 {
     GLint logicalTextureUnit = -1;
@@ -226,6 +226,8 @@ GLint Program::getSamplerMapping(SamplerType type, unsigned int samplerIndex)
     return -1;
 }
 
+// Returns the texture type for a given Direct3D 9 sampler type and
+// index (0-15 for the pixel shader and 0-3 for the vertex shader).
 TextureType Program::getSamplerTextureType(SamplerType type, unsigned int samplerIndex)
 {
     switch (type)