HYDRA-1326 : Various fixes for the custom GLSLFX shader

lib/flowViewport/usdPlugins/shadersDiscoveryPlugin/shaders/customBasicLightingShader.glslfx

@@ -76,11 +76,15 @@ surfaceShader(vec4 Peye, vec3 Neye, vec4 color, vec4 patchCoord)
     //vec2 st = HdGet_st().xy;//This doesn't work unless you add a texture node in the material network
 
     //Get the vertex colors from the prim vars of the quad primitive
-    vec3 vertexColors = HdGet_displayColor().rgb;
+	#ifdef HD_HAS_displayColor
+		vec3 vertexColors = HdGet_displayColor().rgb;
+	#else
+		vec3 vertexColors = vec3(1);
+	#endif
 
     vec3 ambientColor = vec3(0);//Hardcoded
     //Get the value of the custom color float3 parameter from the material, it is named "FVP_CustomColor"
-    vec3 diffuseColor = HdGet_FVP_CustomColor() *0.5 +  vertexColors*0.5;//Blend the custom color with the vertex colors
+    vec3 diffuseColor = HdGet_FVP_CustomColor() * vertexColors;//Blend the custom color with the vertex colors
     vec3 specularColor = vec3(1);//Hardcoded
 
     vec3 n = Neye;

lib/mayaHydra/flowViewportAPIExamples/customShadersNode/mhCustomShadersNode.cpp

@@ -608,6 +608,11 @@ void MhCustomShaders::addedToModelCb()
     //Data producer scene index interface is used to add the retained scene index to all viewports with all render delegates
     auto& dataProducerSceneIndexInterface = Fvp::DataProducerSceneIndexInterface::get();
     dataProducerSceneIndexInterface.addDataProducerSceneIndex(_retainedSceneIndex, noPrefix, (void*)&obj, FvpViewportAPITokens->allViewports,FvpViewportAPITokens->allRenderers);
+
+    //Update color
+    MPlug colorPlug(obj, mColor);
+    const double3& color = colorPlug.asMDataHandle().asDouble3();
+    UpdateColorInShader(color);
 }
 
 void MhCustomShaders::removedFromModelCb()