Make sure bind-to-create chunks don't affect object state

* e.g. if the 'wrong' VAO was bound at the time we replayed a
  bind-to-create chunk, then we'd trample that VAO state (and it might not
  ever be restored). So when reading, not executing, save and restore the
  buffer binding.

renderdoc/driver/gl/gl_resources.cpp

@@ -608,6 +608,46 @@ GLenum TextureBinding(GLenum target)
 	return eGL_NONE;
 }
 
+GLenum BufferBinding(GLenum target)
+{
+	switch(target)
+	{
+		case eGL_ARRAY_BUFFER:
+			return eGL_ARRAY_BUFFER_BINDING;
+		case eGL_ATOMIC_COUNTER_BUFFER:
+			return eGL_ATOMIC_COUNTER_BUFFER_BINDING;
+		case eGL_COPY_READ_BUFFER:
+			return eGL_COPY_READ_BUFFER_BINDING;
+		case eGL_COPY_WRITE_BUFFER:
+			return eGL_COPY_WRITE_BUFFER_BINDING;
+		case eGL_DRAW_INDIRECT_BUFFER:
+			return eGL_DRAW_INDIRECT_BUFFER_BINDING;
+		case eGL_DISPATCH_INDIRECT_BUFFER:
+			return eGL_DISPATCH_INDIRECT_BUFFER_BINDING;
+		case eGL_ELEMENT_ARRAY_BUFFER:
+			return eGL_ELEMENT_ARRAY_BUFFER_BINDING;
+		case eGL_PIXEL_PACK_BUFFER:
+			return eGL_PIXEL_PACK_BUFFER_BINDING;
+		case eGL_PIXEL_UNPACK_BUFFER:
+			return eGL_PIXEL_UNPACK_BUFFER_BINDING;
+		case eGL_QUERY_BUFFER:
+			return eGL_QUERY_BUFFER_BINDING;
+		case eGL_SHADER_STORAGE_BUFFER:
+			return eGL_SHADER_STORAGE_BUFFER_BINDING;
+		case eGL_TEXTURE_BUFFER:
+			return eGL_TEXTURE_BUFFER_BINDING;
+		case eGL_TRANSFORM_FEEDBACK_BUFFER:
+			return eGL_TRANSFORM_FEEDBACK_BUFFER_BINDING;
+		case eGL_UNIFORM_BUFFER:
+			return eGL_UNIFORM_BUFFER_BINDING;
+		default:
+			break;
+	}
+
+	RDCERR("Unexpected target %x", target);
+	return eGL_NONE;
+}
+
 GLenum TextureTarget(GLenum target)
 {
 	switch(target)

renderdoc/driver/gl/gl_resources.h

@@ -48,6 +48,8 @@ GLenum TextureBinding(GLenum target);
 GLenum TextureTarget(GLenum target);
 bool IsProxyTarget(GLenum target);
 
+GLenum BufferBinding(GLenum target);
+
 enum GLNamespace
 {
 	eResUnknown = 0,

renderdoc/driver/gl/wrappers/gl_buffer_funcs.cpp

@@ -101,10 +101,19 @@ bool WrappedOpenGL::Serialise_glBindBuffer(GLenum target, GLuint buffer)
 		}
 		else
 		{
+			// if we're just reading, make sure not to trample state (e.g. element array buffer
+			// binding in a VAO), since this is just a bind-to-create chunk.
+			GLuint prevbuf = 0;
+			if(m_State == READING)
+				m_Real.glGetIntegerv(BufferBinding(Target), (GLint *)&prevbuf);
+
 			GLResource res = GetResourceManager()->GetLiveResource(Id);
 			m_Real.glBindBuffer(Target, res.name);
 
 			m_Buffers[GetResourceManager()->GetLiveID(Id)].curType = Target;
+
+			if(m_State == READING)
+				m_Real.glBindBuffer(Target, prevbuf);
 		}
 	}