投射阴影时，从灯光的角度来看，对象被视为实体.

When casting shadows, objects are treated as solid from the point of view of the light.

但是您可以做的是指定一个使用 alphaTest 的 customDepthMaterial.此自定义深度材质用于阴影计算.

But what you can do is specify a customDepthMaterial that utilizes alphaTest. This custom depth material is used in the shadow calculation.

此处有此技术的示例:http://threejs.org/examples/webgl_animation_cloth.html.

There is an example of this technique here: http://threejs.org/examples/webgl_animation_cloth.html.

three.js r.63

three.js r.63