Speed - Texture Lookups and Structured Buffers

miguel petersen · 2014-04-21T12:21:19

Hi guys, so currently I'm following the deferred pipeline, storing the normals/depths/etc.. in different render targets. Now I'm not proud of it, but each single time I render a, e.g., point light, I reconstruct the position and normals per pixel, and then do some lighting calculations, a single pass of a point light takes around 500 us. Now for performance I though it would be better if I packed the gbuffer into a structured buffer, so I did. I construct the gbuffer from the textures in the compute shader bound as a UAV, then access it in the pixel shader for lighting as a SRV. I was expecting an increase in performance, as texture lookups are expensive, but instead rendering a point light took around 1000 us. For the unpacked gbuffer, I have 3 float4 textures, and in the packed gbuffer, the structured buffer consists of 2 float4 and 1 float3. Now my question is how are the speeds when comparing texture lookups and structured buffers, is it supposed to be like this? Or am I doing something wrong? I apologize that I do not have the source code, but at the moment I do not have access to the machine where the source code is on. When I get access, I'll post it, should be within a few hours. Thank you for your time -MIGI0027