From ec98c7fe03e699364fbb745cbe0c6a591264e4a9 Mon Sep 17 00:00:00 2001
From: manuelk <mkraemer@pixar.com>
Date: Thu, 30 Jan 2014 17:29:14 -0800
Subject: [PATCH] Move VBO buffer allocation out of allocate() and into
 BindVBO()

fixes #256
---
 opensubdiv/osd/cpuGLVertexBuffer.cpp | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/opensubdiv/osd/cpuGLVertexBuffer.cpp b/opensubdiv/osd/cpuGLVertexBuffer.cpp
index 2b1dfd87..98369dd3 100644
--- a/opensubdiv/osd/cpuGLVertexBuffer.cpp
+++ b/opensubdiv/osd/cpuGLVertexBuffer.cpp
@@ -39,7 +39,10 @@ OsdCpuGLVertexBuffer::OsdCpuGLVertexBuffer(int numElements, int numVertices)
 OsdCpuGLVertexBuffer::~OsdCpuGLVertexBuffer() {
 
     delete[] _cpuBuffer;
-    glDeleteBuffers(1, &_vbo);
+    
+    if (_vbo) {
+        glDeleteBuffers(1, &_vbo);
+    }
 }
 
 OsdCpuGLVertexBuffer *
@@ -72,17 +75,23 @@ OsdCpuGLVertexBuffer::GetNumVertices() const {
 
 float*
 OsdCpuGLVertexBuffer::BindCpuBuffer() {
+
     _dataDirty = true; // caller might modify data
     return _cpuBuffer;
 }
 
 GLuint
 OsdCpuGLVertexBuffer::BindVBO() {
+
     if (not _dataDirty)
         return _vbo;
 
     int size = GetNumElements() * GetNumVertices() * sizeof(float);
 
+    if (not _vbo) {
+        glGenBuffers(1, &_vbo);
+    }
+
     glBindBuffer(GL_ARRAY_BUFFER, _vbo);
     glBufferData(GL_ARRAY_BUFFER, size, _cpuBuffer, GL_STATIC_DRAW);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
@@ -93,15 +102,9 @@ OsdCpuGLVertexBuffer::BindVBO() {
 
 bool
 OsdCpuGLVertexBuffer::allocate() {
+
     _cpuBuffer = new float[GetNumElements() * GetNumVertices()];
     _dataDirty = true;
-    int size = GetNumElements() * GetNumVertices() * sizeof(float);
-
-    glGenBuffers(1, &_vbo);
-    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
-    glBufferData(GL_ARRAY_BUFFER, size, 0, GL_STATIC_DRAW);
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
-
     return true;
 }