On Tue, Jun 5, 2012 at 12:42 PM, Gregg Tavares (社用) <firstname.lastname@example.org
> On Tue, Jun 5, 2012 at 12:37 PM, Florian Bösch <email@example.com
>> On Tue, Jun 5, 2012 at 9:29 PM, Gregg Tavares (社用) <firstname.lastname@example.org
>>> In trying to implement this I'm running into issues
>>> #1) it looks like we'll need to restrict depth textures to level 0 only.
>>> Reason: WebGL requires that we clear textures. Otherwise you could
>>> potential read uninitialized memory.
>>> We can clear a depth texture by attaching to an FBO and calling glClear
>>> but we can only attach to level 0
>>> in OpenGL ES 2.0 which means it's impossible to clear levels > 0.
>> I think that's fine, you can also only render to level 0 to other textures
>> unless you have that other extension. Afaik the oes depth texture extension
>> makes no mention that you should be able to render to level 1 and upwards.
>>> #2) What should we do about GL_DEPTH_STENCIL format?
>>> WebGL requires support for GL_DEPTH_STENCIL as a renderbuffer format.
>>> It seems like it also needs to require support for GL_DEPTH_STENCIL as a
>>> texture format for WEBGL_depth_texture
>>> otherwise it's possible you can't use stencils with depth textures.
>>> I'm not sure what issues that brings up.
>> I don't think it is required that any combination of things you attach to
>> an FBO does work. Some combinations will fail (they're also failing right
>> now). It is required that at least some combination allows you to render to
>> a stencil, depth and color buffer, but unless you try and validate the FBO,
>> you're not gonna know.
> It's not required. The question is do we want to support stencils at all
> used with depth textures? IIRC Desktop GLs don't support creating a separate
> depth and stencil and attaching both. The only way to get both depth and
> stencil at the same time is to use DEPTH_STENCIL. So, if we don't add
> DEPTH_STENCIL support to WEBGL_depth_texture then there will effectively be
> no way to use a stencil with a depth texture. Of course maybe my memory is
> bad. I thought that's why we added DEPTH_STENCIL in the first place to WebGL
> but I could be remembering incorrectly.