160 336 m 272 336 l 272 416 l 160 416 l h Shader 1 Shader 2\\ \ \\ \ \\ $G_x=\left(\begin{array}{c}1\\2\\1\end{array}\right)G_{x_1}$, $G_y=\left(\begin{array}{c}1\\0\\-1\end{array}\right)G_{y_1}$, $|G|=\sqrt{G_x^2+G_y^2}$ 192 176 m 352 176 l 352 256 l 192 256 l h $\left(\begin{array}{ccc}-1 & 0 & 1\end{array}\right)$\\ \ \\ \ \\ $G_{x_1}$ $\left(\begin{array}{ccc}1 & 2 & 1\end{array}\right)$\\ \ \\ \ \\ $G_{y_1}$ Pass 1 256 400 m 256 320 l 208 400 m 208 320 l 232 448 m 232 480 l