basic: added tiled animation

basic/tiled_animation.glsl

@@ -0,0 +1,42 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform float u_time;
+
+#define PI 3.14159265358979323846
+
+vec2 rotate2D(vec2 _st, float _angle){
+    _st -= 0.5;
+    _st =  mat2(cos(_angle),-sin(_angle),
+                sin(_angle),cos(_angle)) * _st;
+    _st += 0.5;
+    return _st;
+}
+
+vec2 tile(vec2 _st, float _zoom){
+    _st *= _zoom;
+    return fract(_st);
+}
+
+float box(vec2 _st, vec2 _size, float _smoothEdges){
+    _size = vec2(0.5)-_size*0.5;
+    vec2 aa = vec2(_smoothEdges*0.5);
+    vec2 uv = smoothstep(_size,_size+aa,_st);
+    uv *= smoothstep(_size,_size+aa,vec2(1.0)-_st);
+    return uv.x*uv.y;
+}
+
+void main(void){
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+    vec3 color = vec3(0.0);
+
+    st = tile(st,4.);
+    st = rotate2D(st,PI*0.25);
+
+    color = vec3(box(st*(sin(u_time)),vec2(0.7),0.01));
+    color += vec3(st*(sin(u_time)),0.0);
+
+    gl_FragColor = vec4(color,1.0);
+}