Add vector_sub_vector and vector_dot to basics

src/basics.c

@@ -52,6 +52,18 @@ vector_mult_vector(Vector3 v, Vector3 f)
 }
 
 
+/*
+ * vector_sub_vector --
+ *
+ * Subtract s from m. Return a new vector.
+ */
+Vector3
+vector_sub_vector(Vector3 m, Vector3 s)
+{
+    return vector_init(m.x - s.x, m.y - s.y, m.z - s.z);
+}
+
+
 /*
  * vector_length2 --
  *
@@ -76,6 +88,13 @@ vector_length(Vector3 v)
 }
 
 
+float
+vector_dot(Vector3 v, Vector3 f)
+{
+    return (v.x * f.x) + (v.y * f.x) + (v.z * f.z);
+}
+
+
 /*
  * vector_normalize --
  *

src/basics.h

@@ -23,8 +23,11 @@ extern const Vector3 ZeroVector3;
 Vector3 vector_init(float x, float y, float z);
 Vector3 vector_mult_scalar(Vector3 v, float f);
 Vector3 vector_mult_vector(Vector3 v, Vector3 f);
+Vector3 vector_sub_vector(Vector3 m, Vector3 s);
 float vector_length2(Vector3 v);
 float vector_length(Vector3 v);
+float vector_dot(Vector3 v, Vector3 f);
+
 Vector3 vector_normalize(Vector3 v);