[Public WebGL] WEBGL_multiview discussion

[Florian Bösch]

Addendum: The extension also does not define a formative section on what
identifiers it adds to shaders.

An example of how that works is contained there:
https://www.khronos.org/registry/webgl/extensions/EXT_shader_texture_lod/

Overview
> When this extension is enabled:
>
>    - ...
>
>
>    - ...
>
>
>    - ...
>
>
On Tue, Jan 10, 2017 at 9:12 AM, Florian Bösch <pya...@> wrote:

> The extension adds the following:
>
>    - FRAMEBUFFER_ATTACHMENT_TEXTURE_NUM_VIEWS_OVR accepted by
>    getFramebufferAttachmentParameter
>    - FRAMEBUFFER_ATTACHMENT_TEXTURE_BASE_VIEW_INDEX_OVR accepted by
>    getFramebufferAttachmentParameter
>    - MAX_VIEWS_OVR accepted by getParameter
>    - FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR accepted by
>    checkFramebufferStatus
>    - BACK_LEFT_AND_RIGHT_MULTIVIEW_WEBGL accepted by drawBuffer
>    - framebufferTextureMultiviewWEBGL(...)
>    - context creation parameter "stereo"
>    - gl.drawBuffer
>    - gl.BACK_LEFT
>    - gl.BACK_RIGHT
>    - layout qualifier to specify the number of views a shader renders
>
> There are some issues with that extension:
>
>    1. The enums BACK_LEFT and BACK_RIGHT are added to the
>    WebGLRenderingContextBase instead of the extension objects IDL
>    2. the function drawBuffer which does not exist in WebGL is added to
>    the WebGLRenderingContextBase instead of the extension objects IDL
>    3. The relationship between WebGL2 gl.drawBuffer*s* and this
>    extensions drawBuffer is unclear
>    4. The layout qualifier is not WebGL1 compatible, and the extension
>    does not define WebGL1 usable gl_NumViews constant or the like
>    5. The extension does not contain a differentiation between WebGL1 and
>    WebGL2, but those need to be 2 specifications, so either there's two
>    extensions needed, or this extension needs to define differing
>    functionality in different sections for both WebGL1 and WebGL2
>    6. The examples section is insufficient, examples should be added for
>    context creation and back buffer use, framebuffer object use and selection
>    of traditional or stereo view rendering.
>    7. Since this extension is meant to interact with the WebVR
>    specification, and the WebVR specification so far requires the application
>    to render to the back buffer in split-view, the interaction with WebVR is
>    unclear and should be clarified
>
>
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