Redesigned distortion shader, added chromatic aberration

examples/resources/shaders/glsl100/distortion.fs

@@ -29,36 +29,37 @@ Right Screen Center = {0.75, 0.5, 0, 0}
 Right Lens Center = {0.712005913, 0.5, 0, 0}
 */
 
-// Scales input texture coordinates for distortion.
-vec2 HmdWarp(vec2 in01, vec2 LensCenter)
-{
-    vec2 theta = (in01 - LensCenter)*ScaleIn; // Scales to [-1, 1]
-    float rSq = theta.x*theta.x + theta.y*theta.y;
-    vec2 rvector = theta*(HmdWarpParam.x + HmdWarpParam.y*rSq + HmdWarpParam.z*rSq*rSq + HmdWarpParam.w*rSq*rSq*rSq);
-
-    return LensCenter + Scale*rvector;
-}
-
 void main()
 {
-    // SOURCE: http://www.mtbs3d.com/phpbb/viewtopic.php?f=140&t=17081
-    
     // The following two variables need to be set per eye
     vec2 LensCenter = fragTexCoord.x < 0.5 ? LeftLensCenter : RightLensCenter;
     vec2 ScreenCenter = fragTexCoord.x < 0.5 ? LeftScreenCenter : RightScreenCenter;
+    
+    // Scales input texture coordinates for distortion: vec2 HmdWarp(vec2 fragTexCoord, vec2 LensCenter)
+    vec2 theta = (fragTexCoord - LensCenter)*ScaleIn;   // Scales to [-1, 1]
+    float rSq = theta.x*theta.x + theta.y*theta.y;
+    vec2 theta1 = theta*(HmdWarpParam.x + HmdWarpParam.y*rSq + HmdWarpParam.z*rSq*rSq + HmdWarpParam.w*rSq*rSq*rSq);
+    //vec2 tc = LensCenter + Scale*theta1;
+    
+    // Detect whether blue texture coordinates are out of range since these will scaled out the furthest
+    vec2 thetaBlue = theta1*(ChromaAbParam.z + ChromaAbParam.w*rSq);
+    vec2 tcBlue = LensCenter + Scale*thetaBlue;
 
-    vec2 tc = HmdWarp(fragTexCoord, LensCenter);
+    if (any(bvec2(clamp(tcBlue, ScreenCenter - vec2(0.25, 0.5), ScreenCenter + vec2(0.25, 0.5)) - tcBlue))) gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
+    else
+    {
+        // Do blue texture lookup
+        float blue = texture2D(texture0, tcBlue).b;
 
-    if (any(bvec2(clamp(tc,ScreenCenter-vec2(0.25,0.5), ScreenCenter+vec2(0.25,0.5)) - tc))) gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
-    else gl_FragColor = texture2D(texture0, tc);
-    
-    /*
-    // Chromatic aberration is caused when a lens can't focus every color to the same focal point. 
-    // A simple way to fake this effect, and render it as a quick full-screen post-process, 
-    // is to apply an offset to each color channel in a fragment shader.
-    vec4 rValue = texture2D(texture0, fragTexCoord - rOffset);  
-    vec4 gValue = texture2D(texture0, fragTexCoord - gOffset);
-    vec4 bValue = texture2D(texture0, fragTexCoord - bOffset);
-    finalColor = vec4(rValue.r, gValue.g, bValue.b, 1.0);
-    */
+        // Do green lookup (no scaling)
+        vec2 tcGreen = LensCenter + Scale*theta1;
+        float green = texture2D(texture0, tcGreen).g;
+
+        // Do red scale and lookup
+        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);
+    }
 }

examples/resources/shaders/glsl330/distortion.fs

@@ -17,7 +17,7 @@ const vec2 RightScreenCenter = vec2(0.75, 0.5);
 const vec2 Scale = vec2(0.25, 0.45);    //vec2(0.1469278, 0.2350845);
 const vec2 ScaleIn = vec2(4, 2.2222);
 const vec4 HmdWarpParam = vec4(1, 0.22, 0.24, 0);
-const vec4 ChromaAbCorrection = vec4(0.99599999, -0.0040000002, 1.0140001, 0.0);
+const vec4 ChromaAbParam = vec4(0.996, -0.004, 1.014, 0.0);
 
 /*
 // Another set of default values
@@ -31,37 +31,38 @@ Right Screen Center = {0.75, 0.5, 0, 0}
 Right Lens Center = {0.712005913, 0.5, 0, 0}
 */
 
-// Scales input texture coordinates for distortion.
-vec2 HmdWarp(vec2 in01, vec2 LensCenter)
-{
-    vec2 theta = (in01 - LensCenter)*ScaleIn; // Scales to [-1, 1]
-    float rSq = theta.x*theta.x + theta.y*theta.y;
-    vec2 rvector = theta*(HmdWarpParam.x + HmdWarpParam.y*rSq + HmdWarpParam.z*rSq*rSq + HmdWarpParam.w*rSq*rSq*rSq);
-
-    return LensCenter + Scale*rvector;
-}
-
 void main()
 {
-    // SOURCE: http://www.mtbs3d.com/phpbb/viewtopic.php?f=140&t=17081
-    
     // The following two variables need to be set per eye
     vec2 LensCenter = fragTexCoord.x < 0.5 ? LeftLensCenter : RightLensCenter;
     vec2 ScreenCenter = fragTexCoord.x < 0.5 ? LeftScreenCenter : RightScreenCenter;
+    
+    // Scales input texture coordinates for distortion: vec2 HmdWarp(vec2 fragTexCoord, vec2 LensCenter)
+    vec2 theta = (fragTexCoord - LensCenter)*ScaleIn;   // Scales to [-1, 1]
+    float rSq = theta.x*theta.x + theta.y*theta.y;
+    vec2 theta1 = theta*(HmdWarpParam.x + HmdWarpParam.y*rSq + HmdWarpParam.z*rSq*rSq + HmdWarpParam.w*rSq*rSq*rSq);
+    //vec2 tc = LensCenter + Scale*theta1;
+    
+    // Detect whether blue texture coordinates are out of range since these will scaled out the furthest
+    vec2 thetaBlue = theta1*(ChromaAbParam.z + ChromaAbParam.w*rSq);
+    vec2 tcBlue = LensCenter + Scale*thetaBlue;
 
-    vec2 tc = HmdWarp(fragTexCoord, LensCenter);
+    if (any(bvec2(clamp(tcBlue, ScreenCenter - vec2(0.25, 0.5), ScreenCenter + vec2(0.25, 0.5)) - tcBlue))) finalColor = vec4(0.0, 0.0, 0.0, 1.0);
+    else
+    {
+        // Do blue texture lookup
+        float blue = texture(texture0, tcBlue).b;
 
-    if (any(bvec2(clamp(tc, ScreenCenter - vec2(0.25, 0.5), ScreenCenter + vec2(0.25, 0.5)) - tc))) finalColor = vec4(0.0, 0.0, 0.0, 1.0);
-    else finalColor = texture2D(texture0, tc);
-    
-    // Chromatic aberration is caused when a lens can't focus every color to the same focal point. 
-    // A simple way to fake this effect, and render it as a quick full-screen post-process, 
-    // is to apply an offset to each color channel in a fragment shader.
-    /*
-    vec4 rValue = texture2D(texture0, fragTexCoord - ChromaAbCorrection.x);  
-    vec4 gValue = texture2D(texture0, fragTexCoord - ChromaAbCorrection.y);
-    vec4 bValue = texture2D(texture0, fragTexCoord - ChromaAbCorrection.z);
+        // Do green lookup (no scaling)
+        vec2 tcGreen = LensCenter + Scale*theta1;
+        float green = texture(texture0, tcGreen).g;
+
+        // Do red scale and lookup
+        vec2 thetaRed = theta1*(ChromaAbParam.x + ChromaAbParam.y*rSq);
+        vec2 tcRed = LensCenter + Scale*thetaRed;
+        float red = texture(texture0, tcRed).r;
 
-    finalColor = vec4(rValue.r, gValue.g, bValue.b, 1.0);
-    */
+        finalColor = vec4(red, green, blue, 1.0);
+    }
 }
+