> On Nov 6, 2017, at 7:36 PM, Karoly Balogh (Charlie/SGR)
> <[email protected]> wrote:
>
> But anyway, I guess this is not so useful for you any more. So if you can
> tell what *actually* you want to do, like convert a vec4 of GLSL float to
> Pascal, or convert a 32bit RGBA value to a GLSL vec4, maybe that would be
> more easy to help you with.
I need to encode an integer (2 byte word is actually enough) into the pixels of
a 2D texture where each component is a byte (0-255). In the shader I then
decode that value from the pixel (RGB value) of the texture. It’s for sorting
value in a 2D game
I guess I need to pay attention to byte swapping (not a big problem right?) but
your example writeln((c.a shl 24) + (c.b shl 16) + (c.g shl 8) + c.a; is
basically what I needed, however I’m using an older version of GLSL which
doesn’t have bit shift operators.
Another user contacted me privately and suggested this method using just
arithmetic. From the vec3 I translate the fraction back to 0-255 then basically
do what you did with bit shifting. I can kind of see how this is shifting by
256 each time which is the size of a byte and therefore bit shifting.
float unpack (vec3 c) {
c.r = c.r*255;
c.g = c.g*255;
c.b = c.b*255;
return floor(c.r + c.g * 256 + c.b * 256 * 256);
}
I think I got this solved but i need to implement it fully.
Regards,
Ryan Joseph
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