m_p3DDevice->SetRenderState ( D3DRENDERSTATE_TEXTUREMAG, D3DFILTER_LINEAR );
m_p3DDevice->SetRenderState ( D3DRENDERSTATE_TEXTUREMIN, D3DFILTER_LINEAR );

m_p3DDevice->SetRenderState ( D3DRENDERSTATE_TEXTUREMAG, D3DFILTER_NEAREST );
m_p3DDevice->SetRenderState ( D3DRENDERSTATE_TEXTUREMIN, D3DFILTER_NEAREST );

レンダリングステータスに設定があった時代ってなかったっけ？