From 7154a283f343684ec66bc9fa5bd089f4cc272f47 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Tue, 20 Oct 2020 08:27:32 -0400
Subject: math: vector: Add vec2-cross procedure.

---
 chickadee/math/vector.scm | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/chickadee/math/vector.scm b/chickadee/math/vector.scm
index e2720c6..3476326 100644
--- a/chickadee/math/vector.scm
+++ b/chickadee/math/vector.scm
@@ -34,6 +34,7 @@
             vec2-y
             vec2-magnitude
             vec2-dot-product
+            vec2-cross
             vec2-normalize
             set-vec2-x!
             set-vec2-y!
@@ -243,6 +244,10 @@ polar coordinate (R, THETA) with an arbitrary ORIGIN point."
      (* (vec3-y v1) (vec3-y v2))
      (* (vec3-z v1) (vec3-z v2))))
 
+(define-inlinable (vec2-cross v1 v2)
+  (- (* (vec2-x v1) (vec2-x v2))
+     (* (vec2-y v1) (vec2-y v2))))
+
 (define-inlinable (vec3-cross! dest v1 v2)
   (set-vec3! dest
              (- (* (vec3-y v1) (vec3-z v2))
-- 
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