angle utility methods

public/blah/math/calc.cpp

@@ -119,6 +119,12 @@ float Calc::angle_diff(float radians_a, float radians_b)
 	return mod((radians_b - radians_a) + PI, TAU) - PI;
 }
 
+float Calc::angle_lerp(float radians_a, float radians_b, float p)
+{
+	const auto shortest_angle = mod(mod(radians_b - radians_a, TAU) + (TAU + PI), TAU) - PI;
+	return radians_a + mod(shortest_angle * p, TAU);
+}
+
 float Calc::lerp(float a, float b, float t)
 {
 	return a + (b - a) * t;

public/blah/math/calc.h

@@ -61,6 +61,8 @@ namespace Blah
 		float snap(float val, float interval);
 
 		float angle_diff(float radians_a, float radians_b);
+		
+		float angle_lerp(float radians_a, float radians_b, float p);
 
 		float lerp(float a, float b, float t);
 

public/blah/math/vec2.cpp

@@ -35,6 +35,17 @@ Vec2 Vec2::normal() const
 	float length = this->length();
 	return Vec2(x / length, y / length);
 }
+
+Vec2 Vec2::turn_right() const
+{
+	return Vec2(y, -x);
+}
+
+Vec2 Vec2::turn_left() const
+{
+	return Vec2(-y, x);
+}
+
 float Vec2::length() const { return sqrtf(x * x + y * y); }
 float Vec2::length_squared() const { return x * x + y * y; }
 

public/blah/math/vec2.h

@@ -35,6 +35,8 @@ namespace Blah
 		bool operator !=(const Vec2& rhs);
 		
 		Vec2 normal() const;
+		Vec2 turn_right() const;
+		Vec2 turn_left() const;
 		float length() const;
 		float length_squared() const;
 		Vec2 perpendicular() const;