1 files changed, 37 insertions, 0 deletions
diff --git a/sketches/04/polka.frag b/sketches/04/polka.frag
new file mode 100644
index 0000000..1a93292
--- /dev/null
+++ b/sketches/04/polka.frag
@@ -0,0 +1,37 @@
+varying vec4 v_position;
+uniform vec2 u_resolution;
+uniform float u_time;
+
+#define MAX_ITERATIONS 100
+#define DOTS 32.
+
+void main() {
+  float time = u_time * 2.;
+
+  float ratio = u_resolution.x / u_resolution.y;
+  vec2 pos = v_position.xy/vec2(1.0, ratio);
+
+  gl_FragColor = vec4(0., 0., 0., 1.);
+
+  float segment = 2.0 / (DOTS + 1.);
+
+  for (float i = 0.; i < DOTS; i++) {
+    for (float j = 0.; j < DOTS; j++) {
+      int alt = int(mod(i + j, 2.));
+      vec2 step = vec2(segment * (i + 1.0), segment * (j + 1.0));
+      float radius = (sin(time - length(pos)) + 1.)*0.02;
+      if (alt == 0) {
+        radius = (0.04 - radius);
+      }
+
+      if (length(pos - 1. + step) < radius) {
+        if (alt == 0) {
+          gl_FragColor = vec4(.17, .24, .31, 1.);
+        } else {
+          gl_FragColor = vec4(0.75, 0.22, 0.17, 1.);
+        }
+      }
+    }
+  }
+}
+