- canvas坐标
- 视图坐标
- canvas坐标与视图坐标的转换
1.将原点转到屏幕中间即 x - 0.5*CanvasWidth
2.做归一化处理 (x - 0.5*CanvasWidth)/(0.5*CanvasWidth)
即最终 (event.clientX / window.innerWidth) * 2 - 1;
1.将原点转到屏幕中间即 x - 0.5*CanvasWidth
2.做归一化处理 (x - 0.5*CanvasWidth)/(0.5*CanvasWidth)
即最终 (event.clientX / window.innerWidth) * 2 - 1;