Comme=
nt # 12
on bug 10660=
1
from Yunchao He
(In reply to Ilia Mirkin from comment #9)
> "Color-renderable" means "is it l=
egal to use this format". It does NOT mean
> "the driver allows rendering to this format".
I am not a driver expert. But my understanding is that color-renderable mea=
ns
that we can render into this format as a color buffer. If color-renderable
means "is it legal to use this format", then I can't explain thes=
e two
questions as follows:=20
1. why we need to list that format which is illegal to use at all in spec? I
suppose there are many formats for graphics/video. Enumerating formats that=
are
not useful for texture (or renderbuffer) seems to be weird.=20
2. If color-renderable(or renderable) means that "is it legal to use t=
his
format" for a texture. Then that format is not allow to sample from. I=
f so, how
to distinguish these two kinds of formats: 1) some formats can be supported=
by
a texture to sample only, they can't be used to render into as a render ta=
rget
via fbo, 2) some other formats can be supported by a texture to sample, and
render into as well.
The statement that "Color-renderable means is it legal to use this for=
mat. It
does NOT mean the driver allows rendering to this format" is correct f=
or a
renderbuffer, but I think it is incorrect for a texture. Because a renderbu=
ffer
is only used to render into, they can't be used to sample from. But this is=
sue
is talking about texture, NOT renderbuffer. Maybe for the underlying
implementation, both texture and renderbuffer are mapped into the same GPU
memory (or even CPU memory), but from the perspective of users, texture and
renderbuffer are quite different.