Fix OSD crash bug within CUDA & CL compute modules :

- remove the GL error check in cudaGLVertexBuffer :
  * unrelated GL errors left on the stack were triggering erroneous
  vertexBuffer allocation errors
  * we should not be checking for GL errors here anyway (as most other
  buffer allocations aren't checked either)

- add some pointer checking in the GL / D3D drawContexts in case the
  vertexBuffer pointers passed are NULL

- add some additional typedefs in OsdError to report some of the new
  CUDA / GL related errors

examples/glutViewer/viewer.cpp

@@ -944,8 +944,6 @@ bindProgram(Effect effect, OpenSubdiv::OsdPatchArray const & patch)
     }
     glActiveTexture(GL_TEXTURE0);
 
-    checkGLErrors("bindProgram leave");
-
     return program;
 }
 

opensubdiv/osd/cudaGLVertexBuffer.cpp

@@ -65,6 +65,7 @@
 #include <cuda_gl_interop.h>
 
 #include "../osd/cudaGLVertexBuffer.h"
+#include "../osd/error.h"
 
 #include <cassert>
 
@@ -88,6 +89,7 @@ OsdCudaGLVertexBuffer::Create(int numElements, int numVertices) {
     OsdCudaGLVertexBuffer *instance =
         new OsdCudaGLVertexBuffer(numElements, numVertices);
     if (instance->allocate()) return instance;
+    OsdError(OSD_CUDA_GL_ERROR,"OsdCudaGLVertexBuffer::Create failed.\n");
     delete instance;
     return NULL;
 }
@@ -131,15 +133,13 @@ OsdCudaGLVertexBuffer::allocate() {
 
     int size = _numElements * _numVertices * sizeof(float);
     GLint prev = 0;
-
+    
     glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &prev);
     glGenBuffers(1, &_vbo);
     glBindBuffer(GL_ARRAY_BUFFER, _vbo);
     glBufferData(GL_ARRAY_BUFFER, size, 0, GL_STREAM_DRAW);
     glBindBuffer(GL_ARRAY_BUFFER, prev);
 
-    if (glGetError() != GL_NO_ERROR) return false;
-
     // register vbo as cuda resource
     cudaError_t err = cudaGraphicsGLRegisterBuffer(
         &_cudaResource, _vbo, cudaGraphicsMapFlagsNone);

opensubdiv/osd/d3d11DrawContext.h

@@ -87,6 +87,9 @@ public:
            ID3D11DeviceContext *pd3d11DeviceContext,
            bool requirePtexCoordinates = false,
            bool requireFVarData = false) {
+        
+        if (not vertexBuffer)
+            return NULL;
 
         OsdD3D11DrawContext * instance = new OsdD3D11DrawContext();
         if (instance->allocate(farMesh,

opensubdiv/osd/error.h

@@ -70,6 +70,8 @@ typedef enum {
     OSD_CL_PROGRAM_BUILD_ERROR,
     OSD_CL_KERNEL_CREATE_ERROR,
     OSD_CL_RUNTIME_ERROR,
+    OSD_CUDA_GL_ERROR,
+    OSD_GL_ERROR,
     OSD_GLSL_COMPILE_ERROR,
     OSD_GLSL_LINK_ERROR,
     OSD_D3D11_COMPILE_ERROR,

opensubdiv/osd/glDrawContext.h

@@ -93,6 +93,9 @@ public:
            bool requirePtexCoordinates=false,
            bool requireFVarData=false) {
 
+        if (not vertexBuffer) 
+            return NULL;
+
         OsdGLDrawContext * instance = new OsdGLDrawContext();
         if (instance->allocate(farMesh,
                                vertexBuffer->BindVBO(),