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Re: [Public WebGL] readPixles() can't access float values (OES_texture_float interaction)



The fundamental issue is that rendering to an FP framebuffer takes a lot of additional transistors. Because of this, I doubt if any OpenGL ES 2.0 implementations support rendering to an FP framebuffer. It is likely found only on desktop OpenGL. This is also why OES_texture_floatadds only float texture support not FP framebuffer support.

Regards

-Mark



On 2011/08/30 17:31, Kenneth Russell wrote:
Understood -- I was actually looking at the 2.0.25 spec.

To resolve the issue of rendering to floating-point textures, I
propose defining a pair of OpenGL ES 2.0 extensions
("OES_render_texture_float" / "OES_render_texture_half_float"?) which
define support for FLOAT and HALF_FLOAT_OES texture attachments to
FBOs. Does that sound like a reasonable path to take at this point in
time? I think that adding the minimal amount of spec text and
functionality would be the best direction to take. For example, it
doesn't seem necessary to provide control over clamping behavior.

Another option would be to extend the WebGL extensions exposing
OES_texture_float and OES_texture_half_float ([1], [2]) with enough
language to allow, but not require, an implementation to support these
texture types as FBO color attachments.

I think that we should preserve the capability to render to
floating-point textures from WebGL wherever possible. Existing use
cases ([3], [4], [5], [6], and I'm sure there are more) demonstrate
how compelling this capability is.

[1] http://www.khronos.org/registry/webgl/extensions/OES_texture_float/
[2] http://www.khronos.org/registry/webgl/extensions/OES_texture_half_float/
[3] http://www.ibiblio.org/e-notes/webgl/gpu/contents.htm
[4] http://madebyevan.com/webgl-path-tracing/
[5] http://madebyevan.com/webgl-water/
[6] http://webglsamples.googlecode.com/hg/hdr/hdr.html

-Ken
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