1 files changed, 32 insertions, 0 deletions
diff --git a/sketches/03/flow.frag b/sketches/03/flow.frag
new file mode 100644
index 0000000..b878df9
--- /dev/null
+++ b/sketches/03/flow.frag
@@ -0,0 +1,32 @@
+#define CELL_COUNT 10.0
+
+varying vec4 v_position;
+uniform vec2 u_resolution;
+uniform float u_time;
+
+uniform sampler2D testImage;
+
+struct Particle {
+  vec2 position;
+  vec2 velocity;
+};
+
+bool is_between(vec2 pos, vec2 min, vec2 max) {
+  return pos.x > min.x && pos.x < max.x && pos.y > min.y && pos.y < max.y;
+}
+
+void main() {
+  float time = sin(u_time);
+  float ratio = u_resolution.x / u_resolution.y;
+  vec2 pos = (v_position.xy + 1.)/2./vec2(1.0, ratio);
+
+  float cell_size = 1.0/CELL_COUNT;
+  vec2 cell_pos = cell_size * abs(floor(pos / cell_size));
+
+  gl_FragColor = vec4(0., 0., 0., 1.);
+  if (is_between(pos, cell_pos, cell_pos + cell_size)) {
+    vec4 tex = texture2D(testImage, cell_pos);
+    float value = (tex.r + tex.g + tex.b) / 3.;
+    gl_FragColor = vec4(value, value, value, 1.0);
+  }
+}