1 files changed, 115 insertions, 0 deletions
diff --git a/include/mbgl/util/math.hpp b/include/mbgl/util/math.hpp
new file mode 100644
index 0000000000..277fdc8fc3
--- /dev/null
+++ b/include/mbgl/util/math.hpp
@@ -0,0 +1,115 @@
+#ifndef MBGL_UTIL_MATH
+#define MBGL_UTIL_MATH
+
+#include <cmath>
+#include <array>
+
+#include "vec.hpp"
+
+namespace mbgl {
+namespace util {
+
+
+template <typename T>
+inline T max(T a, T b) {
+    return b > a ? b : a;
+}
+
+template <typename T>
+inline T max(T a, T b, T c) {
+    return max(max(a, b), c);
+}
+
+template <typename T>
+inline T max(T a, T b, T c, T d) {
+    return max(max(a, b), max(c, d));
+}
+
+template <typename T>
+inline T min(T a, T b) {
+    return b < a ? b : a;
+}
+
+template <typename T>
+inline T min(T a, T b, T c) {
+    return min(min(a, b), c);
+}
+
+template <typename T>
+inline T min(T a, T b, T c, T d) {
+    return min(min(a, b), min(c, d));
+}
+
+// Find the angle of the two vectors, solving the formula for the cross product
+// a x b = |a||b|sin(θ) for θ.
+template <typename T = double, typename S>
+inline T angle_between(S ax, S ay, S bx, S by) {
+    return std::atan2((ax * by - ay * bx), ax * bx + ay * by);
+}
+
+template <typename T = double, typename S>
+inline T angle_between(const vec2<S>& a, const vec2<S>& b) {
+    return angle_between(a.x, a.y, b.x, b.y);
+}
+
+template <typename T = double, typename S>
+inline T angle_to(const vec2<S>& a, const vec2<S>& b) {
+    return std::atan2(a.y - b.y, a.x - b.x);
+}
+
+template <typename T, typename S1, typename S2>
+inline T interp(S1 a, S2 b, T t) {
+    return (a * ((T)1 - t)) + (b * t);
+}
+
+// Reflect an angle around 0 degrees
+template <typename T>
+inline std::array<T, 2> flip(const std::array<T, 2>& c) {
+    return {{
+        static_cast<T>(2 * M_PI - c[0]),
+        static_cast<T>(2 * M_PI - c[1])
+    }};
+}
+
+template <typename T, typename S1, typename S2>
+inline vec2<T> normal(const S1& a, const S2& b) {
+    T dx = b.x - a.x;
+    T dy = b.y - a.y;
+    T c = std::sqrt(dx * dx + dy * dy);
+    return { dx / c, dy / c };
+}
+
+template <typename T, typename S1, typename S2>
+inline T dist(const S1& a, const S2& b) {
+    T dx = b.x - a.x;
+    T dy = b.y - a.y;
+    T c = std::sqrt(dx * dx + dy * dy);
+    return c;
+}
+
+template <typename T>
+inline T length(T a, T b) {
+    return std::sqrt(a * a + b * b);
+}
+
+// Take the magnitude of vector a.
+template <typename T = double, typename S>
+inline T mag(const S& a) {
+    return std::sqrt(a.x * a.x + a.y * a.y);
+}
+
+template <typename T>
+T clamp(T value, T min, T max) {
+    return value < min ? min : (value > max ? max : value);
+}
+
+template <typename T>
+T smoothstep(T edge0, T edge1, T x) {
+    T t = clamp((x - edge0) / (edge1 - edge0), T(0), T(1));
+    return t * t * (T(3) - T(2) * t);
+}
+
+}
+}
+
+#endif