PDA

View Full Version : Cast texture or renderbuffer to different type



Dark Photon
04-14-2011, 06:13 PM
Is it possible to typecast a texture or renderbuffer to a different type?

In other words, detach the data from its type container and reattach it to a different type container. Don't think so but I wanted to be sure.

Why would I ask?: I'd like to use OpenCL to do a reduction on the depth buffer (texture or renderbuffer -- don't care). The concept isn't new -- it was presented at SIGGRAPH last year for instance.

The problem is that OpenCL only lets you attach to color buffers, not depth buffers (with clCreateFromGLTexture2D (http://www.khronos.org/registry/cl/sdk/1.1/docs/man/xhtml/clCreateFromGLTexture2D.html) and clCreateFromGLRenderbuffer (http://www.khronos.org/registry/cl/sdk/1.1/docs/man/xhtml/clCreateFromGLRenderbuffer.html)). For instance, even though it supports GL_R32F (1 GL_FLOAT), by spec, it just won't take GL_DEPTH_COMPONENT32F (also 1 GL_FLOAT).

I can additionally write depth redundantly to a GL_R32F color channel just to appease this GL->CL limitation, but I'd rather not if it's avoidable.

Dark Photon
04-14-2011, 06:21 PM
Alternatively, is it possible in GLSL to use shared memory and do cooperative operations between threads including barrier syncs on the same GPU multiprocessor core yet?

It's not designed for this, so I doubt it. But doesn't hurt to ask. :)