Matrix.cs

using System;

namespace SharpEngine {
	public struct Matrix {
		// i wrote this line here manually:
		public float m11, m12, m13, m14;
		// i cloned above line and changed digits (3x):
		public float m21, m22, m23, m24;
		public float m31, m32, m33, m34;
		public float m41, m42, m43, m44;

		// generated using `ctorf`:
		public Matrix(float m11, float m12, float m13, float m14, float m21, float m22, float m23, float m24, float m31, float m32, float m33, float m34, float m41, float m42, float m43, float m44) {
			this.m11 = m11; this.m12 = m12; this.m13 = m13; this.m14 = m14;
			this.m21 = m21; this.m22 = m22; this.m23 = m23; this.m24 = m24;
			this.m31 = m31; this.m32 = m32; this.m33 = m33; this.m34 = m34;
			this.m41 = m41; this.m42 = m42; this.m43 = m43; this.m44 = m44;
		}

		public static Matrix Identity => new Matrix( 1, 0, 0, 0,
			0, 1, 0, 0,
			0, 0, 1, 0,
			0, 0, 0, 1);

		public static Vector operator *(Matrix m, Vector v) {
			return new Vector(m.m11 * v.x + m.m12 * v.y + m.m13 * v.z + m.m14 * 1,
							  m.m21 * v.x + m.m22 * v.y + m.m23 * v.z + m.m24 * 1,
							  m.m31 * v.x + m.m32 * v.y + m.m33 * v.z + m.m34 * 1);
		}

		public static Vector Transform(Matrix m, Vector v, float w = 1f) {
			return new Vector(m.m11 * v.x + m.m12 * v.y + m.m13 * v.z + m.m14 * w,
							  m.m21 * v.x + m.m22 * v.y + m.m23 * v.z + m.m24 * w,
							  m.m31 * v.x + m.m32 * v.y + m.m33 * v.z + m.m34 * w);
		}
		
		public static Matrix operator *(Matrix a, Matrix b) {
			return new Matrix(	
				b.m11*a.m11+b.m21*a.m12+b.m31*a.m13+b.m41*a.m14,
				b.m12*a.m11+b.m22*a.m12+b.m32*a.m13+b.m42*a.m14,
				b.m13*a.m11+b.m23*a.m12+b.m33*a.m13+b.m43*a.m14,
				b.m14*a.m11+b.m24*a.m12+b.m34*a.m13+b.m44*a.m14,

				b.m11*a.m21+b.m21*a.m22+b.m31*a.m23+b.m41*a.m24,
				b.m12*a.m21+b.m22*a.m22+b.m32*a.m23+b.m42*a.m24,
				b.m13*a.m21+b.m23*a.m22+b.m33*a.m23+b.m43*a.m24,
				b.m14*a.m21+b.m24*a.m22+b.m34*a.m23+b.m44*a.m24,

				b.m11*a.m31+b.m21*a.m32+b.m31*a.m33+b.m41*a.m34,
				b.m12*a.m31+b.m22*a.m32+b.m32*a.m33+b.m42*a.m34,
				b.m13*a.m31+b.m23*a.m32+b.m33*a.m33+b.m43*a.m34,
				b.m14*a.m31+b.m24*a.m32+b.m34*a.m33+b.m44*a.m34,

				b.m11*a.m41+b.m21*a.m42+b.m31*a.m43+b.m41*a.m44,
				b.m12*a.m41+b.m22*a.m42+b.m32*a.m43+b.m42*a.m44,
				b.m13*a.m41+b.m23*a.m42+b.m33*a.m43+b.m43*a.m44,
				b.m14*a.m41+b.m24*a.m42+b.m34*a.m43+b.m44*a.m44);
		}

		public static Matrix Translation(Vector translation) {
			var result = Identity;
			result.m14 = translation.x;
			result.m24 = translation.y;
			result.m34 = translation.z;
			return result;
		}

		public static Matrix Scale(Vector scale) {
			var result = Identity;
			result.m11 = scale.x;
			result.m22 = scale.y;
			result.m33 = scale.z;
			return result;
		}

		static Matrix RotationX(float x) {
			var result = Identity;
			result.m22 = MathF.Cos(x);
			result.m23 = -MathF.Sin(x);
			result.m32 = MathF.Sin(x);
			result.m33 = MathF.Cos(x);
			return result;
		}

		static Matrix RotationY(float y) {
			var result = Identity;
			result.m11 = MathF.Cos(y);
			result.m31 = -MathF.Sin(y);
			result.m13 = MathF.Sin(y);
			result.m33 = MathF.Cos(y);
			return result;
		}

		static Matrix RotationZ(float z) {
			var result = Identity;
			result.m11 = MathF.Cos(z);
			result.m12 = -MathF.Sin(z);
			result.m21 = MathF.Sin(z);
			result.m22 = MathF.Cos(z);
			return result;
		}

		public static Matrix Rotation(Vector rotation) {
			return RotationZ(rotation.z) * RotationY(rotation.y) * RotationX(rotation.x);
		}
		
		public static Matrix Perspective(float fov, float aspectRatio, float nearPlane, float farPlane)
		{
			float yScale = 1.0f / MathF.Tan(fov * 0.5f);
			float xScale = yScale / aspectRatio;
			float Q = farPlane / (farPlane - nearPlane);

			return new Matrix(xScale, 0.0f, 0.0f, 0.0f,
					0.0f, yScale, 0.0f, 0.0f,
					0.0f, 0.0f, Q, Q * nearPlane,
					0.0f, 0f, -1f, 0.0f);
		}
	}
}