R2VB and AA with FBOs on ATI cards - when?

OpenGL OpenGL: Advanced Coding
1

Hi,

I have seen Humus’ new “Infinite Terrain” Demo, which utilises Render2VertexBuffer. A moment ago I saw the new ATI SDK, which has a lot of new samples with R2VB. I have searched the extension registry for an extension, but I have nothing found :frowning:
Is there an extension for R2VB? Is this a DirectX-only feature? If there is no extension currently, when can we expect one?

Ah, and when I was looking in the extension registry I found an extension for using multisampling AA with FBOs. AFAIR “FarCry” supports this via DirectX. When will be the implementation of that extension finished on ATI cards?

Thanks, Enrico

2

R2VB is currently DX only. ATI had it in the GL driver in form of experimental support for uber-buffers a couple of years ago already, but that didn’t go so well with the ARB and ultimately we got FBOs instead, which doesn’t have this ability. The ARB may decide to add it to FBOs at some point.

3

Ok, thanks :slight_smile:
And what about the multisampling-for-FBO extension?

Originally posted by Humus:
R2VB is currently DX only. ATI had it in the GL driver in form of experimental support for uber-buffers a couple of years ago already, but that didn’t go so well with the ARB and ultimately we got FBOs instead, which doesn’t have this ability. The ARB may decide to add it to FBOs at some point.
Are there any plans to support this feature with an extra extension?

4

I don’t know when multisampling will be supported or when/if we’ll get R2VB for FBOs.

5

You can R2VB indirectly today:
Render to texture or framebuffer
Bind a PBO
ReadPixels (async copies the rendered image to the PBO)
Bind the PBO as a VBO
render using the VBO

This involves a copy which can be implemented in-band so as not to cause a pipeline stall. The copy itself is unlikely to cause a noticeable performance hit, depending on the size, the implementation, and whatever else is happening in your scene.