i am writing a shader that does a sort-of-lightwriting.
It writes to two render targets, one being the output,
the other being a difference image for future lookups.
The shader runs fine under windows, but under osx
( nv hardware, all on the same machine ) i have to do a
strange color swizzle.
A simple texture lookup, that generally looks like this
Code :vec4 col_now = texture2D(live_texture, texCoord);
has to be swizzled now:
Code :vec4 col_now = texture2D(live_texture, texCoord).grab;
I am somewhat disturbed by the swizzle pattern,
i would understand 'rgba', 'argb' 'bgra' .. all known
and common, but 'grab' ??
does anyone know what happened to my data to require this?
I cant even imagine a texture format that does this
swizzling. The shader uses gl_FragData, is this somehow