diff --git a/learning/hello_world/main.frag b/learning/hello_world/main.frag
new file mode 100644
index 0000000..78a21c9
--- /dev/null
+++ b/learning/hello_world/main.frag
@@ -0,0 +1,17 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform float u_time;
+
+vec4 col() {
+  float r = abs(sin(u_time));
+  float g = abs(cos(u_time/2.0));
+  float b = abs(tan(u_time/3.0));
+  return vec4(r, g, b, 1.0);
+}
+
+void main() {
+  gl_FragColor = vec4(col());
+}
+
diff --git a/readme.md b/readme.md
new file mode 100644
index 0000000..e69de29