/// <summary> /// Build a rotation matrix from the specified axis/angle rotation. /// </summary> /// <param name="axis">The axis to rotate about.</param> /// <param name="angle">Angle in radians to rotate counter-clockwise (looking in the direction of the given axis).</param> /// <param name="result">A matrix instance.</param> public static void CreateFromAxisAngle(Vector3F axis, float angle, out Matrix4F result) { float cos = (float)System.Math.Cos(-angle); float sin = (float)System.Math.Sin(-angle); float t = 1.0f - cos; axis.Normalize(); result = new Matrix4F(t * axis.X * axis.X + cos, t * axis.X * axis.Y - sin * axis.Z, t * axis.X * axis.Z + sin * axis.Y, 0.0f, t * axis.X * axis.Y + sin * axis.Z, t * axis.Y * axis.Y + cos, t * axis.Y * axis.Z - sin * axis.X, 0.0f, t * axis.X * axis.Z - sin * axis.Y, t * axis.Y * axis.Z + sin * axis.X, t * axis.Z * axis.Z + cos, 0.0f, 0, 0, 0, 1); }
/// <summary> /// Build a world space to camera space matrix /// </summary> /// <param name="eye">Eye (camera) position in world space</param> /// <param name="target">Target position in world space</param> /// <param name="up">Up vector in world space (should not be parallel to the camera direction, that is target - eye)</param> /// <returns>A Matrix4F that transforms world space to camera space</returns> public static Matrix4F LookAt(Vector3F eye, Vector3F target, Vector3F up) { Vector3F z = Vector3F.Normalize(eye - target); Vector3F x = Vector3F.Normalize(Vector3F.Cross(up, z)); Vector3F y = Vector3F.Normalize(Vector3F.Cross(z, x)); Matrix4F rot = new Matrix4F(new Vector4F(x.X, y.X, z.X, 0.0f), new Vector4F(x.Y, y.Y, z.Y, 0.0f), new Vector4F(x.Z, y.Z, z.Z, 0.0f), Vector4F.UnitW); Matrix4F trans = Matrix4F.CreateTranslation(eye * -1.0f); return(trans * rot); }
/// <summary> /// Build a quaternion from the given axis and angle /// </summary> /// <param name="axis">The axis to rotate about</param> /// <param name="angle">The rotation angle in radians</param> /// <returns></returns> public static Quaternion FromAxisAngle(Vector3F axis, float angle) { if (axis.LengthSquared == 0.0f) { return(Identity); } Quaternion result = Identity; angle *= 0.5f; axis.Normalize(); result.Xyz = axis * (float)System.Math.Sin(angle); result.W = (float)System.Math.Cos(angle); return(Normalize(result)); }