Bug 139148 – Implement renderbufferStorageMultisample as WebGL1 extension

• Component: WebGL
• Status: RESOLVED INVALID

[Roger Fong]

rdar://problem/15949546

Most of the work here is just validation. I assume that the 1.0.3 conformance suite will have a test for this call.

[Roger Fong]

Created attachment 242341 [details]
patch

[Roger Fong]

Some hand testing of this patch shows that the validation is working correctly.
However, I am having some issues getting the actual call to work properly when I have more than 0 samples.

I suspect my test case is incorrect since I don't specify anywhere to render a multisample texture. (texImage2DMultisample) I suspect that without this call the mismatch between a nonmultisampled texture and a render buffer with enough storage for a multisampled frame buffer is causing issues, but I could be wrong.

[Roger Fong]

I have indeed confirmed that the OpenGL call to ::glRenderBufferStorageMultisample is getting called as intended however.

[Roger Fong]

After emailing the Khronos group I got the following response from Kenneth Russel:

I don't mean to discourage your work but this is no small task either
from a specification or implementation standpoint. It would be
necessary to spec out a WebGL 1 extension combining the semantics of
both the ANGLE_framebuffer_blit and ANGLE_framebuffer_multisample
extensions. Users' code also has to be modified to take advantage of
multisampled renderbuffers. I think the effort would be better spent
getting a WebGL 2 implementation ready, which will include this
functionality in the core API.

Indeed renderBufferStorageMultisample has not been specced out and there are no 1.0.x conformance tests testing it. 

TLDR: I don't think we should do this because it never made it into the WebGL spec in the first place.

[Csaba Osztrogonác]

Comment on attachment 242341 [details]
patch

Cleared review? from attachment 242341 [details] so that this bug does not appear in http://webkit.org/pending-review.  If you would like this patch reviewed, please attach it to a new bug (or re-open this bug before marking it for review again).