add distortion animation

BobDeng1974 · Mar 17, 2012 · 08d5e1f · 08d5e1f
1 parent 0a58717
commit 08d5e1f
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Showing 2 changed files with 14 additions and 16 deletions.
diff --git a/TextureWarping-Gridless.c b/TextureWarping-Gridless.c
@@ -30,7 +30,7 @@ struct {
     GLuint FboTexture;
     GLuint FboHandle;
     GLuint QuadVao;
-    float Power;
+    float BarrelPower;
 } Globals;
 
 static GLuint LoadProgram(const char* vsKey, const char* gsKey, const char* fsKey);
@@ -106,6 +106,7 @@ void PezUpdate(float seconds)
     const float RadiansPerSecond = 0.5f;
     Globals.Theta += seconds * RadiansPerSecond;
     //Globals.Theta = Pi / 4;
+    Globals.BarrelPower = 2.0 - 0.5 * (sin(Globals.Theta * 4.0f) + 1.0);
 }
 
 void PezRender()
@@ -182,6 +183,7 @@ void PezRender()
 
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
     glUseProgram(Globals.QuadProgram);
+    glUniform1f(u("BarrelPower"), Globals.BarrelPower);
     glBindTexture(GL_TEXTURE_2D, Globals.FboTexture);
     glBindVertexArray(Globals.QuadVao);
     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

diff --git a/TextureWarping-Gridless.glsl b/TextureWarping-Gridless.glsl
@@ -14,17 +14,18 @@ void main()
 
 in vec2 vTexCoord;
 out vec4 FragColor;
+uniform float BarrelPower = 2.0;
 uniform sampler2D Sampler;
 
-const bool BlackBackground = true;
-const bool BlackBorder = false;
+const vec4 BackgroundColor = vec4(1);
+const bool Border = true;
 
 void main()
 {
     vec2 p = vTexCoord;
     float theta  = atan(p.y,p.x);
     float radius = length(p);
-    radius = radius * radius;
+    radius = pow(radius, BarrelPower);
     p.x = radius * cos(theta);
     p.y = radius * sin(theta);
     vec2 tc = 0.5 * (p + 1.0);
@@ -34,22 +35,17 @@ void main()
     float v = fwidth(q.y);
     float L = 1.0;
 
-    if (BlackBackground) {
-        if (q.x < -u || q.y < -v) {
-            FragColor = vec4(0);
-            return;
-        }
-        if (q.x < u) L *= (q.x/u);
-        if (q.y < v) L *= (q.y/v);
+    if (q.x < -u || q.y < -v) {
+        FragColor = BackgroundColor;
+        return;
     }
 
-    if (BlackBorder) {
-        if (q.x < -u || q.y < -v) {
-            FragColor = vec4(1);
-            return;
-        }
+    if (Border) {
         if (q.x < u) L *= abs(q.x/u);
         if (q.y < v) L *= abs(q.y/v);
+    } else  {
+        if (q.x < u) L *= q.x/u;
+        if (q.y < v) L *= q.y/v;
     }
 
     FragColor = L * texture(Sampler, tc);