Re: [Public WebGL] Implement extension EXT_frag_depth in WebGL

To: Ben Adams <thundercat@illyriad.co.uk>

Subject: Re: [Public WebGL] Implement extension EXT_frag_depth in WebGL

From: Florian Bösch <pyalot@gmail.com>

Date: Thu, 22 Nov 2012 11:07:10 +0100

Cc: public webgl <public_webgl@khronos.org>

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Specified in:

OpenGL: Available in the core specification to OpenGL 2.0, released 2004
OpenGL ES:

Available as extension ES: EXT_frag_depth, released 2010
Available in the core specification to OpenGL ES 3.0, released 2012

Direct3D: Available since Shader Model 2.0, Released with Direct3D 9.0 in 2002

Hardware availability

Desktops: 99.45% (not being DX8 GPUs or below), source: http://store.steampowered.com/hwsurvey
Mobiles: As of November 2012, 7 devices out of 783, source: http://www.glbenchmark.com/result.jsp

Freescale SABRESD-MX6DQ
Huawei MediaPad 10 FHD
Huawei U9508
Huawei U9510
Huawei U9510E
Marvell PXA988
Panasonic Toughpad FZ-A1B

https://github.com/KhronosGroup/WebGL/pull/84

On Thu, Nov 22, 2012 at 5:50 AM, Ben Adams <thundercat@illyriad.co.uk> wrote:

Its been mentioned several times before, however I'd like to request that WEBGL_frag_depth be added to the extensions.

http://www.khronos.org/registry/gles/extensions/EXT/EXT_frag_depth.txt

Previous mentions:

gl_FragDepth and the focus of WebGL
https://www.khronos.org/webgl/public-mailing-list/archives/1204/msg00033.html

Dynamic loops and gl_FragDepth access in fragment shader
https://www.khronos.org/webgl/public-mailing-list/archives/1201/msg00142.html

As mentioned in follow up by Florian Bösch:
This is a useful capability in circumstances where raycasting, raytracing, path-tracing, paralax-mapping, signed distance fields, impostors etc. are involved and rendered together with rasterized geometry.