message: Fix for single-channel textures in MaterialXRenderGlsl
  This changelist fixes the rendering of single-channel textures in MaterialXRenderGlsl, setting the required state that replicates the red channel to RGB.
diff: @@ -138,6 +138,11 @@ bool GLTextureHandler::createRenderResources(ImagePtr image, bool generateMipMap
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glTexImage2D(GL_TEXTURE_2D, 0, glInternalFormat, image->getWidth(), image->getHeight(),
  0, glFormat, glType, image->getResourceBuffer());
  + if (image->getChannelCount() == 1)
  + {
  + GLint swizzleMask[] = { GL_RED, GL_RED, GL_RED, GL_ONE };
  + glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_RGBA, swizzleMask);
  + }
  if (generateMipMaps)
  {
  