added corelib/math/vec.h single header vector math library

src/corelib/math/vec.h

@@ -0,0 +1,43 @@
+#ifndef _vec_math_h
+#define _vec_math_h
+
+#include "math.h"
+
+static inline
+void clamp_magnitude(float* xx, float* yy, float max_magnitude) {
+	float x = *xx, y = *yy;
+	const float m = sqrtf(x*x + y*y);
+	if(m > max_magnitude) {
+		x /= m; y /= m;
+		x *= max_magnitude; y *= max_magnitude;
+	}
+	*xx = x; *yy = y;
+}
+
+static inline
+void normalize(float* xx, float* yy) {
+	float x = *xx, y = *yy;
+	if(x != 0 && y != 0) {
+		const float m = sqrtf(x*x + y*y);
+		x /= m; y /= m;
+		*xx = x; *yy = y;
+	}
+}
+
+static inline
+int move_towards(float* out_x, float* out_y, float x, float y, float tx, float ty, float max_delta) {
+	const float diff_x = tx - x, diff_y = ty - y;
+	const float m = sqrtf(diff_x*diff_x + diff_y*diff_y);
+	const float dir_x = diff_x / m * max_delta, dir_y = diff_y / m * max_delta;
+	if(dir_x < diff_x && dir_y < diff_y) {
+		*out_x = x + dir_x;
+		*out_y = y + dir_y;
+		return 0;
+	} else {
+		*out_x = tx;
+		*out_y = ty;
+		return 1;
+	}
+}
+
+#endif /* _vec_math_h */