Added updated examples from branch

android/examples/OpenGL/Shaders/EdgeDetect/EdgeDetect.pde

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+// This example shows how to change the default fragment shader used
+// in P3D to render textures, by a custom one that applies a simple 
+// edge detection filter.
+//
+// Press any key to switch between the custom and the default shader.
+
+PImage img;
+PShader shader;
+PGraphicsOpenGL pg;  
+boolean usingShader;
+  
+void setup() {
+  size(400, 400, P3D);
+  img = loadImage("berlin-1.jpg");
+    
+  pg = (PGraphicsOpenGL)g;
+  shader = pg.loadShader("edges.glsl", FILL_SHADER_TEX);
+  pg.setShader(shader, FILL_SHADER_TEX);
+  usingShader = true;
+}
+
+public void draw() {
+  image(img, 0, 0, width, height);
+}
+  
+public void keyPressed() {
+  if (usingShader) {
+    pg.resetShader(FILL_SHADER_TEX);
+    usingShader = false;
+  } else {
+    pg.setShader(shader, FILL_SHADER_TEX);
+    usingShader = true;
+  }
+}

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

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+// Edge detection shader
+
+#ifdef GL_ES
+precision mediump float;
+precision mediump int;
+#endif
+
+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);
+}