add maths utils

src/misc/Maths.cpp

@@ -0,0 +1,58 @@
+#include "misc/Maths.h"
+
+namespace td {
+namespace maths {
+
+Mat4f Perspective(float fovY, float aspectRatio, float zNear, float zFar) {
+	const float tanHalfFovy = std::tan(fovY / 2.0f);
+
+	Mat4f result{};
+	result.x0 = 1.0f / (aspectRatio * tanHalfFovy);
+	result.y1 = 1.0f / (tanHalfFovy);
+	result.z2 = -(zFar + zNear) / (zFar - zNear);
+	result.z3 = -1.0f;
+	result.w2 = -(2.0f * zFar * zNear) / (zFar - zNear);
+
+	return result;
+}
+
+Mat4f LookAt(const Vec3f& eye, const Vec3f& center, const Vec3f& up) {
+	const Vec3f f = Normalize(center - eye);
+	const Vec3f s = Normalize(Cross(f, up));
+	const Vec3f u = Cross(s, f);
+
+	Mat4f result = Identity<float>();
+	result.x0 = s.x;
+	result.y0 = s.y;
+	result.z0 = s.z;
+	result.x1 = u.x;
+	result.y1 = u.y;
+	result.z1 = u.z;
+	result.x2 = -f.x;
+	result.y2 = -f.y;
+	result.z2 = -f.z;
+	result.w0 = -Dot(s, eye);
+	result.w1 = -Dot(u, eye);
+	result.w2 = Dot(f, eye);
+
+	return result;
+}
+
+Mat4f Dot(const Mat4f& mat, const Mat4f& other) {
+	Mat4f result {};
+
+	static const int MAT_SIZE = 4;
+
+	for (int i = 0; i < MAT_SIZE; i++) {
+		for (int j = 0; j < MAT_SIZE; j++) {
+			for (int k = 0; k < MAT_SIZE; k++) {
+				result[i * MAT_SIZE + j] += mat[i * MAT_SIZE + k] * other[k * MAT_SIZE + j];
+			}
+		}
+	}
+
+	return result;
+}
+
+} // namespace maths
+} // namespace td