From e88c9c35f965e76adc47ca79d42db2e0e5aeb16c Mon Sep 17 00:00:00 2001
From: hellerve <veit@veitheller.de>
Date: Thu, 8 Jun 2017 10:27:21 -0400
Subject: [PATCH] basic: added moving tiles example

---
 basic/moving_tiles.glsl | 54 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 basic/moving_tiles.glsl

diff --git a/basic/moving_tiles.glsl b/basic/moving_tiles.glsl
new file mode 100644
index 0000000..ccb442e
--- /dev/null
+++ b/basic/moving_tiles.glsl
@@ -0,0 +1,54 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+const float PI = 3.1415926535897932384626433832795;
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+vec2 movingTiles(vec2 _st, float _zoom, float _speed) {
+    _st *= _zoom;
+    float time = u_time*_speed;
+    if(fract(time)>0.5){
+        if (fract( _st.y * 0.5) > 0.5) _st.x += fract(time)*2.0;
+        else _st.x -= fract(time)*2.0;
+    } else {
+        if (fract(_st.x * 0.5) > 0.5) _st.y += fract(time)*2.0;
+        else _st.y -= fract(time)*2.0;
+    }
+    return fract(_st);
+}
+
+float circle(vec2 _st, float _radius) {
+    vec2 pos = vec2(0.5)-_st;
+    return smoothstep(1.0-_radius,1.0-_radius+_radius*0.2,1.-dot(pos,pos)*3.14);
+}
+
+vec2 brickTile(vec2 _st, float _zoom) {
+    _st *= _zoom;
+
+    _st.x += step(1., mod(_st.y,2.0)) * 0.5;
+
+    return fract(_st);
+}
+
+float box(vec2 _st, vec2 _size) {
+    _size = vec2(0.5)-_size*0.5;
+    vec2 uv = smoothstep(_size,_size+vec2(1e-4),_st);
+    uv *= smoothstep(_size,_size+vec2(1e-4),vec2(1.0)-_st);
+    return uv.x*uv.y;
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+    st.x *= u_resolution.x/u_resolution.y;
+
+    st = movingTiles(st,10.,0.5);
+    st = brickTile(st, 0.5);
+
+    vec3 color = vec3(1.0-box(st, vec2(abs(sin(u_time))*0.8+0.1)));
+
+    gl_FragColor = vec4(color,1.0);
+}