shaders

Author: monkstone

processing_app/topics/shaders/data/edgesfrag.glsl

@@ -0,0 +1,37 @@
+#ifdef GL_ES
+precision mediump float;
+precision mediump int;
+#endif
+
+uniform sampler2D texture;
+uniform vec2 texOffset;
+
+varying vec4 vertColor;
+varying vec4 vertTexCoord;
+
+const vec4 lumcoeff = vec4(0.299, 0.587, 0.114, 0);
+
+void main() {
+  vec2 tc0 = vertTexCoord.st + vec2(-texOffset.s, -texOffset.t);
+  vec2 tc1 = vertTexCoord.st + vec2(         0.0, -texOffset.t);
+  vec2 tc2 = vertTexCoord.st + vec2(+texOffset.s, -texOffset.t);
+  vec2 tc3 = vertTexCoord.st + vec2(-texOffset.s,          0.0);
+  vec2 tc4 = vertTexCoord.st + vec2(         0.0,          0.0);
+  vec2 tc5 = vertTexCoord.st + vec2(+texOffset.s,          0.0);
+  vec2 tc6 = vertTexCoord.st + vec2(-texOffset.s, +texOffset.t);
+  vec2 tc7 = vertTexCoord.st + vec2(         0.0, +texOffset.t);
+  vec2 tc8 = vertTexCoord.st + vec2(+texOffset.s, +texOffset.t);
+  
+  vec4 col0 = texture2D(texture, tc0);
+  vec4 col1 = texture2D(texture, tc1);
+  vec4 col2 = texture2D(texture, tc2);
+  vec4 col3 = texture2D(texture, tc3);
+  vec4 col4 = texture2D(texture, tc4);
+  vec4 col5 = texture2D(texture, tc5);
+  vec4 col6 = texture2D(texture, tc6);
+  vec4 col7 = texture2D(texture, tc7);
+  vec4 col8 = texture2D(texture, tc8);
+
+  vec4 sum = 8.0 * col4 - (col0 + col1 + col2 + col3 + col5 + col6 + col7 + col8); 
+  gl_FragColor = vec4(sum.rgb, 1.0) * vertColor; 
+}

processing_app/topics/shaders/edge_filter.rb

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+attr_reader :edges, :apply_filter
+
+def setup
+  sketch_title 'Edge Filter'
+  @apply_filter = true
+  @edges = load_shader(data_path('edges.glsl'))
+  no_stroke
+end
+
+def draw
+  background(0)
+  lights
+  translate(width / 2, height / 2)
+  push_matrix
+  rotate_x(frameCount * 0.01)
+  rotate_y(frameCount * 0.01)
+  box(120)
+  pop_matrix
+  filter(edges) if (apply_filter)
+
+  # The sphere doesn't have the edge detection applied
+  # on it because it is drawn after filter is called.
+  rotate_y(frame_count * 0.02)
+  translate(150, 0)
+  sphere(40)
+end
+
+def mouse_pressed
+  @apply_filter = !apply_filter
+end
+
+def settings
+  size(640, 360, P3D)
+end