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Re: [Public WebGL] invalid framebuffer operation in Firefox




----- Original Message -----
> These limitations are only when you're rendering to an FBO with a
> renderbuffer as the color attachment. If you have an RGBA texture as
> the color attachment you ought to be able to portably get 8 bits per
> channel. (I think...)

You know, I've gone back and forth on this.. section 4.4.5 in the ES 2.0 spec (2.0.24) is unclear.  It states:

>  The internal formats of the attached images can affect the completeness of
>  the framebuffer, so it is useful to ïrst deïne the relationship between the internal
>  format of an image and the attachment points to which it can be attached. Image
>  internal formats are summarized in table 4.5. Color-renderable formats contain
>  red, green, blue, and possibly alpha components; depth-renderable formats contain
>  depth components; and stencil-renderable formats contain stencil components.
>
>  Formats not listed in table 4.5, including compressed internal formats. are not
>  color-, depth-, or stencil-renderable, no matter which components they contain.

Note the usage of the generic "attached images" -- no distinction between a renderbuffer and a texture.  However, the caption for table 4.5 states "Renderbuffer image formats, showing their renderable type ...", explicitly stating Renderbuffer.

But then later on in section 4.4 at the start of page 117:

> Although OpenGL ES deïnes a wide variety of internal formats for
> framebuffer-attachable images, such as texture images and renderbuffer images,
> some implementations may not support rendering to particular combinations of
> internal formats.

and states that checking framebuffer completeness is required.  This seems in direct conflict with the statement that the formats not listed in 4.5 are not renderable, unless the intent was to say "nothing outside of table 4.5 is renderable, but formats in 4.5 /may/ be renderable", which seems wrong.

Is this confusing to anyone else?  I'll file a bug against the ES spec if it's not just me :-)

(Note that we allow attaching a RGBA texture as a framebuffer color attachment without problems, and it works on just about every mobile device I've tried it on.)

    - Vlad

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