[orx-fx] Refactor CMYKHalftone to support customizable elements/colors

orx-fx/src/shaders/glsl/dither/cmyk-halftone.frag

@@ -1,17 +1,27 @@
 /*  Based on CMYK Halftone by tsone https://www.shadertoy.com/view/Mdf3Dn */
 uniform float dotSize;
 
-#define SST 0.888
-#define SSQ 0.288
-
 uniform float scale;
 uniform float rotation;
+uniform float phase;
+
+uniform float blackRotation;
+uniform float yellowRotation;
+uniform float magentaRotation;
+uniform float cyanRotation;
+
+uniform vec4 blackColor;
+uniform vec4 yellowColor;
+uniform vec4 magentaColor;
+uniform vec4 cyanColor;
 
 in vec2 v_texCoord0;
 uniform sampler2D tex0;
 
 out vec4 o_color;
 
+#pragma INSERT_PHRASES
+
 vec4 rgb2cmyki(in vec3 c)
 {
     float k = max(max(c.r, c.g), c.b);
@@ -26,20 +36,20 @@ vec3 u(vec4 c) {
     if (c.a == 0.0) {
         return vec3(0.0);
     } else {
-        return c.rgb/c.a;
+        return c.rgb / c.a;
     }
 
 }
-vec4 cmyki2rgba(in vec4 cmyk){
-    vec4 c = vec4(0.0, 1.0, 1.0, 1.0)*(1.0-cmyk.r);
-    vec4 m = vec4(1.0, 0.0, 1.0, 1.0)*(1.0-cmyk.g);
-    vec4 y = vec4(1.0, 1.0, 0.0, 1.0)*(1.0-cmyk.b);
-    vec4 k = vec4(0.0, 0.0, 0.0, 1.0)*(1.0-cmyk.a);
+vec4 cmyki2rgba(in vec4 cmyk) {
+    vec4 c = cyanColor * (1.0 - cmyk.r);
+    vec4 m = magentaColor * (1.0 - cmyk.g);
+    vec4 y = yellowColor * (1.0 - cmyk.b);
+    vec4 k = blackColor * (1.0 - cmyk.a);
 
     vec4 f = c;
-    f = (1.0-f.a) * m + f.a * vec4(u(f)*u(m),1.0) * m.a + (1.0-m.a) * f;
-    f = (1.0-f.a) * y + f.a * vec4(u(f)*u(y),1.0) * y.a + (1.0-y.a) * f;
-    f = (1.0-f.a) * k + f.a * vec4(u(f)*u(k),1.0) * k.a + (1.0-k.a) * f;
+    f = (1.0 - f.a) * m + f.a * vec4(u(f) * u(m), 1.0) * m.a + (1.0 - m.a) * f;
+    f = (1.0 - f.a) * y + f.a * vec4(u(f) * u(y), 1.0) * y.a + (1.0 - y.a) * f;
+    f = (1.0 - f.a) * k + f.a * vec4(u(f) * u(k), 1.0) * k.a + (1.0 - k.a) * f;
     return f;
 }
 
@@ -56,43 +66,46 @@ vec2 grid(in vec2 px)
 
 vec4 ss(in vec4 v)
 {
-    return smoothstep(vec4(SST-SSQ), vec4(SST+SSQ), v);
+    vec4 vw = fwidth(v);
+    return smoothstep(vec4(-vw), vec4(vw), v);
 }
 
-vec4 halftone(in vec2 fc,in mat2 m)
+
+float halftone(in vec2 fc, in mat2 m, int channel)
 {
-    vec2 smp = (grid(m*fc) + 0.5*scale) * m;
-    float s = min(length(fc-smp) / (dotSize*0.5*scale), 1.0);
-    vec3 texc = texture(tex0, px2uv(smp+vec2(textureSize(tex0, 0))/2.0)).rgb;
-    vec4 c = rgb2cmyki(texc);
-    return c+s;
+    vec2 smp = (grid(m * fc) + 0.5 * scale) * m;
+
+    float s = length(fc - smp) / (dotSize * 2.0 * scale);
+    vec2 d2 = m * ((fc) - smp) / (dotSize * 0.5 * scale);
+    vec3 texc = texture(tex0, px2uv(smp + vec2(textureSize(tex0, 0)) / 2.0)).rgb;
+    float c = 1.0 - rgb2cmyki(texc)[channel];
+    return element(d2, c);
 }
 
-mat2 rotm(in float r)
-{
+mat2 rotm(in float r) {
     float cr = cos(r);
     float sr = sin(r);
-    return mat2(
-    cr,-sr,
-    sr,cr
-    );
+    return mat2(cr, -sr, sr, cr);
 }
 
 void main() {
-    vec2 fc = v_texCoord0 * vec2(textureSize(tex0, 0)) - vec2(textureSize(tex0, 0))/2.0;
+    vec2 fc = (v_texCoord0 - vec2(0.5)) * vec2(textureSize(tex0, 0));
+    fc = domainWarp(fc);
 
-    mat2 mc = rotm(rotation + radians(15.0));
-    mat2 mm = rotm(rotation + radians(75.0));
-    mat2 my = rotm(rotation);
-    mat2 mk = rotm(rotation + radians(45.0));
+    mat2 mc = rotm(rotation + radians(cyanRotation));
+    mat2 mm = rotm(rotation + radians(magentaRotation));
+    mat2 my = rotm(rotation + radians(yellowRotation));
+    mat2 mk = rotm(rotation + radians(blackRotation));
 
-    float k = halftone(fc, mk).a;
-    vec4 c = cmyki2rgba(ss(vec4(
-    halftone(fc, mc).r,
-    halftone(fc, mm).g,
-    halftone(fc, my).b,
-    halftone(fc, mk).a
-    )));
+    vec4 c = cmyki2rgba(
+        ss(vec4(
+           halftone(fc, mc, 0),
+           halftone(fc, mm, 1),
+           halftone(fc, my, 2),
+           halftone(fc, mk, 3)
+           )
+        )
+    );
 
     o_color = c;
 }