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GLSL

@module hueshift
@vs vs
in vec4 coord;
out vec2 texUV;
void main() {
gl_Position = vec4(coord.xy, 0.0, 1.0);
texUV = coord.zw;
}
@end
@fs fs
uniform sampler2D iChannel0;
uniform uniforms {
int is_colorless; // if greater than zero, no color
float target_hue;
};
in vec2 texUV;
out vec4 fragColor;
vec3 rgb2hsv(vec3 c)
{
vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
float d = q.x - min(q.w, q.y);
float e = 1.0e-10;
return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}
vec4 texture2DAA(sampler2D tex, vec2 uv) {
vec2 texsize = vec2(textureSize(tex,0));
vec2 uv_texspace = uv*texsize;
vec2 seam = floor(uv_texspace+.5);
uv_texspace = (uv_texspace-seam)/fwidth(uv_texspace)+seam;
uv_texspace = clamp(uv_texspace, seam-.5, seam+.5);
return texture(tex, uv_texspace/texsize);
}
vec3 hsv2rgb(vec3 c)
{
vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}
void main() {
vec4 outColor = texture2DAA(iChannel0, texUV);
vec3 hsv = rgb2hsv(outColor.rgb);
if(is_colorless > 0)
{
hsv.y = 0.0f;
} else if(hsv.y > 0.5) {
hsv.x = target_hue;
}
fragColor = vec4(hsv2rgb(hsv), outColor.a);
}
@end
@program program vs fs