Create distortion.fs

examples/core/resources/shaders/glsl120/distortion.fs

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+#version 120
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+
+// NOTE: Add your custom variables here
+uniform vec2 leftLensCenter;
+uniform vec2 rightLensCenter;
+uniform vec2 leftScreenCenter;
+uniform vec2 rightScreenCenter;
+uniform vec2 scale;
+uniform vec2 scaleIn;
+uniform vec4 deviceWarpParam;
+uniform vec4 chromaAbParam;
+
+void main()
+{
+    // Compute lens distortion
+    vec2 lensCenter = fragTexCoord.x < 0.5? leftLensCenter : rightLensCenter;
+    vec2 screenCenter = fragTexCoord.x < 0.5? leftScreenCenter : rightScreenCenter;
+    vec2 theta = (fragTexCoord - lensCenter)*scaleIn;
+    float rSq = theta.x*theta.x + theta.y*theta.y;
+    vec2 theta1 = theta*(deviceWarpParam.x + deviceWarpParam.y*rSq + deviceWarpParam.z*rSq*rSq + deviceWarpParam.w*rSq*rSq*rSq);
+    vec2 thetaBlue = theta1*(chromaAbParam.z + chromaAbParam.w*rSq);
+    vec2 tcBlue = lensCenter + scale*thetaBlue;
+
+    if (any(bvec2(clamp(tcBlue, screenCenter - vec2(0.25, 0.5), screenCenter + vec2(0.25, 0.5)) - tcBlue)))
+    {
+        // Set black fragment for everything outside the lens border
+        gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
+    }
+    else
+    {
+        // Compute color chroma aberration
+        float blue = texture2D(texture0, tcBlue).b;
+        vec2 tcGreen = lensCenter + scale*theta1;
+        float green = texture2D(texture0, tcGreen).g;
+
+        vec2 thetaRed = theta1*(chromaAbParam.x + chromaAbParam.y*rSq);
+        vec2 tcRed = lensCenter + scale*thetaRed;
+
+        float red = texture2D(texture0, tcRed).r;
+        gl_FragColor = vec4(red, green, blue, 1.0);
+    }
+}