Allow trial of trasform feedback (for testing/benchmark) on hardware that declares support for GL_EXT_transform_feedback. Performance is far less than satisfactory on my hd4870(ogl3.3 gpu), however. Also messes up texcoords. Don't add RenderUseTransformFeedback to settings.xml.

indra/llrender/llvertexbuffer.cpp

@@ -2083,6 +2083,16 @@ void LLVertexBuffer::flush()
 	}
 }
 
+// bind for transform feedback (quick 'n dirty)
+void LLVertexBuffer::bindForFeedback(U32 channel, U32 type, U32 index, U32 count)
+{
+#if GL_TRANSFORM_FEEDBACK_BUFFER
+	U32 offset = mOffsets[type] + sTypeSize[type]*index;
+	U32 size= (sTypeSize[type]*count);
+	glBindBufferRange(GL_TRANSFORM_FEEDBACK_BUFFER, channel, mGLBuffer, offset, size);
+#endif
+}
+
 // Set for rendering
 void LLVertexBuffer::setBuffer(U32 data_mask)
 {