使用斜线填充区域,并绘制边界 \fill[pattern color=red, pattern=north west lines, opacity=0.4] (0,0) -- (0,1) -- (1,1); \fill[pattern color=red, pattern=north west lines, opacity=0.4, draw] (0,0) -- (0,1) -- (1,1); \filldraw[pattern color=red, pattern=north west lin…