moving the OpenGL examples to the core

java/examples/OpenGL/Shaders/EdgeDetect/EdgeDetect.pde

@@ -0,0 +1,32 @@
+// This example shows how to change the default fragment shader used
+// in P2D to render textures, by a custom one that applies a simple 
+// edge detection filter.
+//
+// Press the mouse to switch between the custom and the default shader.
+
+PImage img;
+PShader edges;  
+boolean customShader;
+  
+void setup() {
+  size(400, 400, P2D);
+  img = loadImage("berlin-1.jpg");
+    
+  edges = (PShader)loadShader("edges.glsl", PShader.TEXTURED);
+  shader(edges, PShader.TEXTURED);
+  customShader = true;
+}
+
+public void draw() {
+  image(img, 0, 0, width, height);
+}
+  
+public void mousePressed() {
+  if (customShader) {
+    resetShader(PShader.TEXTURED);
+    customShader = false;
+  } else {
+    shader(edges, PShader.TEXTURED);
+    customShader = true;
+  }
+}

java/examples/OpenGL/Shaders/EdgeDetect/data/edges.glsl

@@ -0,0 +1,38 @@
+// Edge detection shader
+
+uniform sampler2D textureSampler;
+
+// The inverse of the texture dimensions along X and Y
+uniform vec2 texcoordOffset;
+
+varying vec4 vertColor;
+varying vec4 vertTexcoord;
+
+void main() {
+  vec4 sum = vec4(0);
+
+  float kernel[9];
+  kernel[0] = -1.0; kernel[1] = -1.0; kernel[2] = -1.0;
+  kernel[3] = -1.0; kernel[4] = +8.0; kernel[5] = -1.0;
+  kernel[6] = -1.0; kernel[7] = -1.0; kernel[8] = -1.0;
+
+  vec2 offset[9];
+  offset[0] = vec2(-texcoordOffset.s, -texcoordOffset.t);
+  offset[1] = vec2(              0.0, -texcoordOffset.t);
+  offset[2] = vec2(+texcoordOffset.s, -texcoordOffset.t);
+
+  offset[3] = vec2(-texcoordOffset.s, 0.0);
+  offset[4] = vec2(              0.0, 0.0);
+  offset[5] = vec2(+texcoordOffset.s, 0.0);
+
+  offset[6] = vec2(-texcoordOffset.s, +texcoordOffset.t);
+  offset[7] = vec2(              0.0, +texcoordOffset.t);
+  offset[8] = vec2(+texcoordOffset.s, +texcoordOffset.t);
+
+  for (int i = 0; i < 9; i++) {
+    vec4 tmp = texture2D(textureSampler, vertTexcoord.st + offset[i]);
+    sum += tmp * kernel[i];
+  }
+
+  gl_FragColor = vec4(sum.rgb, 1.0);
+}