Now we can add a light source (I chose from the top right) for this image so later on we can have some dynamic light effect. To do this, go back to the background layer and duplicate it once more.

现在我们来为图片增加光源(我选的是右上方)，这样我们会有一些动感光线效果。

youdao

And so if we wanted to do this here, it's again, the same thing we're just now pulling back this layer and calling them char *s not actually strings.

如果我们想要在这里这样做，再次，我们撤销这一层,把它们叫做char，*s，实际上不是字符串。

哈佛公开课 - 计算机科学课程节选