Revit.SDK.Samples.SlabShapeEditing.CS.Matrix4.Identity C# (CSharp) Method

        public void Identity()
        {
            for (int i = 0; i < 4; i++)
            {
                for (int j = 0; j < 4; j++)
                {
                    this.m_matrix[i, j] = 0.0f;
                }
            }
            this.m_matrix[0, 0] = 1.0f;
            this.m_matrix[1, 1] = 1.0f;
            this.m_matrix[2, 2] = 1.0f;
            this.m_matrix[3, 3] = 1.0f;
        }

        /// <summary>
        /// get a matrix used to rotate object specific angle on Z direction
        /// </summary>
        /// <param name="angle">rotate angle</param>
        /// <returns>matrix which rotate object specific angle on Z direction</returns>
        public static Matrix4 RotateZ(double angle)
        {
            Matrix4 rotateX = new Matrix4();

            rotateX.Type = MatrixType.Rotation;
            rotateX.Identity();
            double sin = (double)Math.Sin(angle);
            double cos = (double)Math.Cos(angle);

            rotateX.Matrix[1, 1] = cos;
            rotateX.Matrix[1, 2] = sin;

            rotateX.Matrix[2, 1] = -sin;
            rotateX.Matrix[2, 2] = cos;
            return(rotateX);
        }