1 uniform sampler2D PREFIX(dither_tex);
2 uniform vec2 PREFIX(tc_scale);
3 uniform float PREFIX(round_fac), PREFIX(inv_round_fac);
5 vec4 FUNCNAME(vec2 tc) {
6 vec4 result = INPUT(tc);
8 // Don't dither alpha; the case of alpha=255 (1.0) is very important to us,
9 // and if there's any inaccuracy earlier in the chain so that it becomes e.g.
10 // 254.8, it's better to just get it rounded off than to dither and have it
11 // possibly get down to 254. This is not the case for the color components.
12 result.rgb += tex2D(PREFIX(dither_tex), tc * PREFIX(tc_scale)).xxx;
14 // NEED_EXPLICIT_ROUND will be #defined to 1 if the GPU has inaccurate
15 // fp32 -> int8 framebuffer rounding, and 0 otherwise.
16 #if NEED_EXPLICIT_ROUND
17 result = round(result * vec4(PREFIX(round_fac))) * vec4(PREFIX(inv_round_fac));