initial: added basic stuff

basic/dancing_sine.glsl

@@ -0,0 +1,22 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform float u_time;
+
+float plot(vec2 st, float pct){
+  return  smoothstep( pct-0.02, pct, st.y) - 
+          smoothstep( pct, pct+0.02, st.y);
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution;
+
+    float y = sin(st.x*u_time);
+
+    float pct = plot(st,y);
+    vec3 color = pct*vec3(0.0,1.0,0.0);
+
+    gl_FragColor = vec4(color,1.0);
+}