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;
+  }
+}