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Re: [Public WebGL] Restricting WebGL exposure of OES_depth_texture





On Wed, Jun 6, 2012 at 1:19 AM, Florian BÃsch <pyalot@gmail.com> wrote:
On Wed, Jun 6, 2012 at 4:25 AM, Gregg Tavares (çç) <gman@google.com> wrote:
Fine, then I ask others reading this list? are depth textures useful without stencils? If you can't use a stencil buffer while using a depth texture will that limit what you can do? It would certainly make the last 2 games I personally shipped impossible but hey, that's just one anecdote. If no one else cares then I'm fine with WEBGL_depth_texture supporting depth only.

I see these use-cases for depth textures:

1) Deferred shading requires at least 2 passes (albedo and byte packed depth/normal). If a floating point texture is used to capture depth/normal, that may be unsupported and/or slow. Depth textures could help to improve the precision attained for depth information while freeing more bytes on the color attachment to use for other things and not consume 4x the amount of bandwidth.

2) Post process blur would benefit from being possible to do with just one pass instead of two.

3) Particle fading for sprites near to scene surfaces would become possible with just one pass instead of two

4) Depth estimation of objects for reasons of subsurface scattering or translucency will require fewer passes.

None of the above relies on stenciling.

What use-cases are you thinking of that would be impossible without stenciling?

Stenciling was used in LocoRoco to keep the faces in the characters since they are based on spring physics it would seriously hard to clip in software.

Stenciling was used in Afro Samurai to provide any shape (ie, non-rectangular) animated comic book like panels.

There's also the issue of fragmentation. We can add DEPTH_STENCIL now since it can be emulated with DEPTH + STENCIL, same as it's emulated in the current WebGL spec. Or we can leave it out and then have 4 more variations. Browsers with neither depth_texture nor stencil, browsers with depth_textures, browsers with depth_stencil and browsers with depth_texture + depth_stencil.

I'd argue the current WebGL spec requires support for DEPTH_STENCIL so we're already guaranteed to have the feature. Why fragment things more by leaving it off here?