private void UpdatePerspectiveMatrix()

in SamplesCommon/SamplesCommon/PerspectivePanel.cs [117:152]
30 lines of code
3 McCabe index (conditional complexity)

        private void UpdatePerspectiveMatrix()
        {
            if (!m_setUpExpressions)
            {
                Vector3 perspectiveOrigin = new Vector3(PerspectiveOriginPercent * m_rootVisual.Size, 0);

                Matrix4x4 transform =
                    Matrix4x4.CreateTranslation(-perspectiveOrigin) *
                    new Matrix4x4(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, -1 / (float)PerspectiveDepth, 0, 0, 0, 1) *
                    Matrix4x4.CreateTranslation(perspectiveOrigin);

                m_rootVisual.TransformMatrix = transform;
            }
            else if (m_matrixExpression == null)
            {
                m_matrixExpression = m_compositor.CreateExpressionAnimation();
                m_matrixExpression.Properties.InsertVector3("LayoutSize", new Vector3(m_rootVisual.Size, 0));

                // Expressions don't have an easy way to convert vector2 to vector3. But having this intermediate expression makes the below expression cleaner anyway.
                var perspectiveOriginExpression = m_compositor.CreateExpressionAnimation(
                    "Vector3(publicProps.PerspectiveOriginPercent.x, publicProps.PerspectiveOriginPercent.y, 0) * props.LayoutSize");
                perspectiveOriginExpression.SetReferenceParameter("publicProps", m_rootVisual.Properties);
                perspectiveOriginExpression.SetReferenceParameter("props", m_matrixExpression.Properties);
                m_matrixExpression.Properties.InsertVector3("PerspectiveOrigin", Vector3.Zero);
                m_matrixExpression.Properties.StartAnimation("PerspectiveOrigin", perspectiveOriginExpression);

                m_matrixExpression.Expression =
                    "Matrix4x4.CreateFromTranslation(-props.PerspectiveOrigin) * " +
                    "Matrix4x4(1,0,0,0,  0,1,0,0,  0,0,1,-1/publicProps.PerspectiveDepth,  0,0,0,1) * " +
                    "Matrix4x4.CreateFromTranslation( props.PerspectiveOrigin)";
                m_matrixExpression.SetReferenceParameter("publicProps", m_rootVisual.Properties);
                m_matrixExpression.SetReferenceParameter("props", m_matrixExpression.Properties);

                m_rootVisual.StartAnimation("TransformMatrix", m_matrixExpression);
            }
        }