Allow creation of projection layers if depth support isn't enabled in the context

Author: cabanier

webxrlayers-1.bs

@@ -874,12 +874,16 @@ If {{XRProjectionLayerInit/depthFormat}} is <code>0</code> the layer will not pr
 
 This is the <dfn>list of depth formats for projection layers</dfn> that the [=XR Compositor=] MUST support:
 
-For WebGL1 contexts with the '{{WEBGL_depth_texture}}' [=extension=] enabled or WebGL2 contexts:
+For {{WebGLRenderingContext}} contexts with the '{{WEBGL_depth_texture}}' [=extension=] enabled or WebGL2 contexts:
 
  - {{DEPTH_COMPONENT}}
  - {{DEPTH_STENCIL}}
 
-For WebGL2 contexts these additional formats are supported:
+If the extension was not enabled, the request for a depth texture is ignored.
+
+NOTE: this could be confusing to authors because they might expect a depth texture. If possible, provide a warning with the reason why the texture was not created.
+
+For {{WebGL2RenderingContext}} contexts these additional formats are supported:
 
  - {{DEPTH_COMPONENT24}}
  - {{DEPTH24_STENCIL8}}
@@ -940,12 +944,12 @@ If {{XRLayerInit/depthFormat}} is not supplied, the layer will not provide a dep
 
 This is the <dfn>list of depth formats for non-projection layers</dfn> that the [=XR Compositor=] MUST support:
 
-For WebGL1 contexts with the '{{WEBGL_depth_texture}}' [=extension=] enabled or WebGL2 contexts:
+For {{WebGLRenderingContext}} contexts with the '{{WEBGL_depth_texture}}' [=extension=] enabled or WebGL2 contexts:
 
  - {{DEPTH_COMPONENT}}
  - {{DEPTH_STENCIL}}
 
-For WebGL2 contexts these additional formats are supported:
+For {{WebGL2RenderingContext}} contexts these additional formats are supported:
 
  - {{DEPTH_COMPONENT24}}
  - {{DEPTH24_STENCIL8}}
@@ -1147,10 +1151,11 @@ To <dfn>allocate color textures for projection layers</dfn> using an {{XRProject
 <div class="algorithm" data-algorithm="allocate depth textures for projection layers">
 
 To <dfn>allocate depth textures for projection layers</dfn> using an {{XRProjectionLayer}} |layer|, an {{XRTextureType}} |textureType|, a {{GLenum}} |textureFormat| and a float |scaleFactor|, the user agent MUST run the following steps:
-  1. let |array| be a [=new=] array in the [=relevant realm=] of |context|.
-  1. let |context| be |layer|'s [=XRCompositionLayer/context=].
-  1. let |session| be |layer|'s [=XRCompositionLayer/session=].
+  1. Let |array| be a [=new=] array in the [=relevant realm=] of |context|.
+  1. Let |context| be |layer|'s [=XRCompositionLayer/context=].
+  1. Let |session| be |layer|'s [=XRCompositionLayer/session=].
   1. If |textureFormat| is <code>0</code>, return |array| and abort these steps.
+  1. If |context| is a {{WebGLRenderingContext}} and the {{WEBGL_depth_texture}} [=extension=] is not enabled in |context|, return |array| and abort these steps.
   1. If |textureFormat| is not in the [=list of depth formats for projection layers=], throw a {{NotSupportedError}} and abort these steps.
   1. let |numViews| be the number of the |session|'s [=list of views=] excluding the [=secondary view|secondary views=].
   1. Let |view| be the first entry in the |session|'s [=list of views=] that is not a [=secondary view=].
@@ -1206,6 +1211,7 @@ To <dfn>allocate the depth textures for the secondary views</dfn> using an {{XRP
   1. Let |context| be |layer|'s [=XRCompositionLayer/context=].
   1. Let |session| be |layer|'s [=XRCompositionLayer/session=].
   1. If |textureFormat| is <code>0</code>, return |array| and abort these steps.
+  1. If |context| is a {{WebGLRenderingContext}} and the {{WEBGL_depth_texture}} [=extension=] is not enabled in |context|, return |array| and abort these steps.
   1. If |textureFormat| is not in the [=list of depth formats for projection layers=], throw a {{NotSupportedError}} and abort these steps.
   1. Let |array| be a [=new=] array in the [=relevant realm=] of |context|.
   1. For each |view| in the |session|'s [=list of views=]: