I implemented planar shadows with the function D3DXMatrixShadow. As you know, we need plane and light factor to calculate a shadow matrix. The problem is that when I set the plane as D3DXPLANE p(0, -1, 0, 0.1f), the shadows by directional light are correctly rendered, but the shadows by point light are not rendered. However, if I use D3DXPLANE p(0, 1, 0, 0.1f), the situation is reversed, shadows by directional light are not drawn, the shadows by point light are ok. I cannot understand why it happens. Is it normal or am i missing something? Please explain to me why this happens. Thanks in advance.