From b2761ae673806df33831245a5f2208b7b49251c6 Mon Sep 17 00:00:00 2001
From: Ben Houston <neuralsoft@gmail.com>
Date: Wed, 29 Jul 2020 12:28:13 -0400
Subject: [PATCH] feat: add mat2RotateDirection

---
 src/lib/shaders/includes/math/mat2.glsl | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/lib/shaders/includes/math/mat2.glsl b/src/lib/shaders/includes/math/mat2.glsl
index 92a30ccd..bc699158 100644
--- a/src/lib/shaders/includes/math/mat2.glsl
+++ b/src/lib/shaders/includes/math/mat2.glsl
@@ -4,10 +4,16 @@ mat2 mat2Identity() {
   return mat2( 1., 0., 0., 1. );
 }
 
-// https://thebookofshaders.com/08/
+mat2 mat2RotateDirection( vec2 dir ){
+  return mat2( dir.x, -dir.y, dir.y, dir.x );
+}
+
+// validated - this is the same as the TS makeMatrix3RotationFromAngle
 mat2 mat2Rotate(float angle){
-  float c = cos(angle);
-  float s = sin(angle);
+  return mat2RotateDirection( vec2( cos(angle), sin(angle) ) );
+}
 
-  return mat2( c, -s, s, c );
+// validated - this is the same as the TS makeMatrix3Scale
+mat2 mat2Scale(vec2 scale){
+  return mat2( scale.x, 0., scale.y, 0 );
 }