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Re: [Public WebGL] question about implementation of anti-aliasing; and a remark for benchmark authors




On 2011-02-02, at 10:24 AM, Benoit Jacob wrote:


Hi,

Two parts in this email:

*** Question about implementing anti-aliasing ***

In an earlier thread, Adrienne kindly pointed me to Chromium's implementation of antialiasing:
http://src.chromium.org/viewvc/chrome/trunk/src/chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc?annotate=70474#l79

But in Mozilla's implementation, we do all the rendering into a FBO.

My understanding was that just requiring samples and sample buffers at GL context creation time was not enough to get multisampling on FBOs, and that for that I needed the GL_EXT_framebuffer_multisample extension (part of OpenGL 3.0).

Is that correct?

Correct.  On desktop GL you need EXT_framebuffer_blit + EXT_framebuffer_multisample  *OR* ARB_framebuffer_object (which is basically a "roll-up" extension of the functionality which went into GL 3.0).

If yes, how does Chromium/WebKit handle this problem? Are you also doing your rendering into a FBO, or a PBuffer?

Chrome (when using ANGLE at least) renders to an FBO.  ANGLE provides the GL_ANGLE_framebuffer_blit and GL_ANGLE_framebuffer_multisample extensions to expose the necessary FBO multisample support.

Hope this helps,
Daniel

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                        Daniel Koch -+- daniel@transgaming.com
Senior Graphics Architect -+- TransGaming Inc.  -+- www.transgaming.com