[orx-jumpflood] Make module multiplatform

orx-jumpflood/src/shaders/glsl/straight-skeleton.frag

@@ -0,0 +1,46 @@
+uniform sampler2D tex0;// signed distance
+uniform vec4 skeletonColor;
+uniform vec4 backgroundColor;
+uniform vec4 foregroundColor;
+uniform float angleTreshold;
+
+in vec2 v_texCoord0;
+
+out vec4 o_color;
+
+void main() {
+    vec4 ct = texture(tex0, v_texCoord0);
+    vec2 cd = normalize(ct.xy);
+    vec2 step = 1.0 / vec2(textureSize(tex0, 0));
+
+    float minDistance = 1000.0;
+
+    vec4 nt = texture(tex0, v_texCoord0 + step * vec2(0.0, -1.0));
+    vec2 nd = normalize(nt.xy);
+    vec4 et = texture(tex0, v_texCoord0 + step * vec2(1.0, 0.0));
+    vec2 ed = normalize(et.xy);
+    vec4 wt = texture(tex0, v_texCoord0 + step * vec2(-1.0, 0.0));
+    vec2 wd = normalize(wt.xy);
+    vec4 st = texture(tex0, v_texCoord0 + step * vec2(0.0, 1.0));
+    vec2 sd = normalize(st.xy);
+
+    float d0 = dot(cd, nd);
+    float d1 = dot(cd, ed);
+    float d2 = dot(cd, wd);
+    float d3 = dot(cd, sd);
+
+    float r = (d0+d1+d2+d3);
+
+    vec4 fc = vec4(0.0);
+
+    if (ct.z > 0.0) {
+        fc += foregroundColor * foregroundColor.a;
+    } else {
+        fc += backgroundColor * backgroundColor.a;
+    }
+
+    if ((d0 < angleTreshold || d1 < angleTreshold || d2 < angleTreshold || d3 < angleTreshold) && ct.z > 0.0 && length(ct.xy) > 4) {
+        fc = fc * (1.0 - skeletonColor.a) + (skeletonColor * skeletonColor.a);
+    }
+    o_color = fc;
+}