Minor improvements to Mesh binding (#1323)

Improve mesh binding in metal renderer to support multiple mesh geometry and prevent repeated binding.

Author: ashwinbhat

source/MaterialXRenderMsl/MslMaterial.mm

@@ -128,7 +128,7 @@
     }
 
     _glProgram->bind(MTL(renderCmdEncoder));
-    if (_boundMesh && mesh->getName() != _boundMesh->getName())
+    if (_boundMesh && mesh != _boundMesh)
     {
         _glProgram->unbindGeometry();
     }

source/MaterialXRenderMsl/MslPipelineStateObject.h

@@ -313,6 +313,9 @@ class MX_RENDERMSL_API MslProgram
     // Metal Device Object
     id<MTLDevice> _device = nil;
 
+    // Currently bound mesh
+    MeshPtr _boundMesh = nullptr;
+
     bool _alphaBlendingEnabled = false;
 
     float _time = 0.0f;

source/MaterialXRenderMsl/MslPipelineStateObject.mm

@@ -347,14 +347,6 @@ int GetStrideOfMetalType(MTLDataType type)
 
     // Bind based on inputs found
     bindViewInformation(cam);
-    if(geometryHandler)
-    {
-        for (const auto& mesh : geometryHandler->getMeshes())
-        {
-            bindMesh(renderCmdEncoder, mesh);
-        }
-    }
-
     bindTimeAndFrame();
     bindLighting(lightHandler, imageHandler);
     bindTextures(renderCmdEncoder, lightHandler, imageHandler);
@@ -468,6 +460,12 @@ int GetStrideOfMetalType(MTLDataType type)
         throw ExceptionRenderError(errorType, errors);
     }
 
+    if (_boundMesh && mesh != _boundMesh)
+    {
+        unbindGeometry();
+    }
+    _boundMesh = mesh;
+
     MslProgram::InputMap foundList;
     const MslProgram::InputMap& attributeList = getAttributesList();
 

source/MaterialXRenderMsl/MslRenderer.mm

@@ -233,6 +233,8 @@
             // Draw all the partitions of all the meshes in the handler
             for (const auto& mesh : _geometryHandler->getMeshes())
             {
+                _program->bindMesh(renderCmdEncoder, mesh);
+
                 for (size_t i = 0; i < mesh->getPartitionCount(); i++)
                 {
                     auto part = mesh->getPartition(i);