diff --git a/learning/hello_world/main.frag b/learning/hello_world/main.frag
index 7d0b166..465e796 100644
--- a/learning/hello_world/main.frag
+++ b/learning/hello_world/main.frag
@@ -6,8 +6,6 @@ uniform float u_time;
 uniform vec2 u_resolution;
 uniform vec2 u_mouse;
 
-
-
 vec4 col() {
   vec2 st = gl_FragCoord.xy/u_resolution;
   vec2 mt = u_mouse/u_resolution;
diff --git a/snippets/rotate/rotate.frag b/snippets/rotate/rotate.frag
new file mode 100644
index 0000000..ccde4fb
--- /dev/null
+++ b/snippets/rotate/rotate.frag
@@ -0,0 +1,3 @@
+vec2 rotate(vec2 st, float a) {
+  return mat2(cos(a),-sin(a),sin(a),cos(a))*(st);
+}
diff --git a/snippets/rotate/rotate.md b/snippets/rotate/rotate.md
new file mode 100644
index 0000000..52e54c1
--- /dev/null
+++ b/snippets/rotate/rotate.md
@@ -0,0 +1,14 @@
+# Rotate
+
+as far as i understand this function, it functions by multiplying a 2d vector by a mat2 (2x2 matrix as far as i can tell) like this:
+
+[[cos(angle),-sin(angle)],       [x,
+[sin(angle),-cos(angle)]]     x   y]
+
+creating something like this:
+```
+st.x = cos(angle)*st.x - sin(angle)*st.x
+st.y = sin(angle)*st.y - cos(angle)*st.y
+```
+although i don't fully understand cos and sin's effect on these values, i feel like i'm a step closer to understand these functions
+