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Re: [Public WebGL] The state of MRTs






On Wed, Mar 21, 2012 at 9:21 AM, Benoit Jacob <bjacob@mozilla.com> wrote:
Like for the other extensions that we recently agreed on, what would probably help the most to get multiple render targets accepted would be detailed analysis of what current mobile hardware can't support them, and what is the prospect for the near future. Then we'll be able to see if a compromise with portability makes sense. Sorry if that analysis was already done in this thread, I admit I didn't read all of it.

On desktops the core functionality is provided by the ARB_framebuffer_object
ARB_framebuffer_object is, in my understanding, a hard requirement to be able to implement WebGL, as framebuffer objects are part of the WebGL API. So, this implies that support for multiple render targets is ubiquitous on desktop GL, except of course that GL_MAX_COLOR_ATTACHMENTS_EXT might be 1.
On Direct3D the the number of render targets is found in D3DCAPS9.NumSumultaneousRTs.
Nice, so the situation seems entirely clear on the desktop.

Mobile support (505 devices, source [5]):
- NV_draw_buffers  2.3% (12 devices)
- NV_fbo_color_attachment 13.6% (69 devices)
- Both: 13.6% (69 devices)
Ouch. 13.6% is very little. Is the percentage much higher if we include only GPUs that still ship in new devices today?

Benoit