Tests for vector functions

engine/components.scm

@@ -56,7 +56,8 @@
 
 ;; Export vector functions
 (export vector-= vector-+ vector-- vector-* vector-/
-	vector-magnitude vector-normalize)
+	vector-magnitude vector-normalize vector-dot
+	vector-angle-between)
 
 ;; TODO: make this function accept any number of vectors
 (define (vector-= vec1 vec2)
@@ -126,6 +127,29 @@
     (sqrt (+ (expt (vector-x vec) 2)
 	     (expt (vector-y vec) 2))))))
 
+(define (vector-dot vec1 vec2)
+  (assert (and (record? vec1)
+	       (record? vec2)))
+  (assert (eq? (rtd-name (record-rtd vec1))
+	       (rtd-name (record-rtd vec2))))
+  (assert (any (lambda (pred) (pred vec1)) (list vector2?)))
+  (cond
+   ((vector2? vec1)
+    (+ (* (vector-x vec1) (vector-x vec2))
+       (* (vector-y vec1) (vector-y vec2))))))
+
+(define (vector-angle-between vec1 vec2)
+  (assert (and (record? vec1)
+	       (record? vec2)))
+  (assert (eq? (rtd-name (record-rtd vec1))
+	       (rtd-name (record-rtd vec2))))
+  (assert (any (lambda (pred) (pred vec1)) (list vector2?)))
+  (cond
+   ((vector2? vec1)
+    (acos (/ (vector-dot vec1 vec2)
+	     (* (vector-magnitude vec1)
+		(vector-magnitude vec2)))))))
+
 ;; Normalization
 (define (vector-normalize vec)
   (assert (any (lambda (pred) (pred vec)) (list vector2?))) ;; TODO: This assertion should be moved out of here

engine/math.scm

@@ -0,0 +1,27 @@
+(module (engine math) ()
+(import scheme
+	(chicken base)
+	(chicken module))
+
+(export PI PI/2)
+(define PI
+  3.141592653589793238462643383279502884197169399375105820974944592307816406286)
+
+(define PI/2
+  (/ PI 2))
+
+(export rad-to-deg deg-to-rad)
+;; Radians and degrees conversion
+(define (rad-to-deg rad)
+  (* rad
+     (/ 180 PI)))
+(define (deg-to-rad deg)
+  (* deg
+     (/ PI 180)))
+
+(export *float-precision* approx-=)
+(define *float-precision* (make-parameter 0.001))
+;; Approximately equal - for real number comparison
+(define (approx-= x y)
+  (< (abs (- x y)) (*float-precision*)))
+)

test/components.scm

@@ -3,6 +3,7 @@
 	(chicken base)
 	(engine core)
 	(engine components core)
+	(engine math)
 	(srfi 78)
 	(srfi 99))
 
@@ -21,4 +22,9 @@
 (check (vector-magnitude (make-vector2 100 0)) => 100)
 (check (vector-= (make-vector2 1 0)
 		 (vector-normalize (make-vector2 100 0))) => #t)
+(check (vector-dot (make-vector2 1 2)
+		   (make-vector2 3 4)) => 11)
+(check (rad-to-deg
+	(vector-angle-between (make-vector2 1 2)
+			      (make-vector2 3 4))) (=> approx-=) 10.305)
 )