The last step to completing our skybox will be adding stars. To get good results with stars, the most important things to remember are blending and variety. We want the stars to meld into the night sky in a natural way, so we have to blend them nicely with the elements already in place. We also want to hide the fact that they are computer generated, and most of them are just colored pixels. To do that, we introduce a lot of variety in them so that the eye is less likely to notice the similarity that gives away those weaknesses.

When using point and billboard star layers, we rely on masking to control their placement. We have two masking strategies to choose from. Our first option is to use the built-in masking available to us in the point and billboard star layers themselves. This option allows the most accurate control over positioning and color. The second method is to use masking noise layers, like we did for our dark background nebula. The second method is great for making background stars to populate our background nebula, because we don't have to create a new mask, we can use the Purple Nebula Ridged Mask we've already made.

There's one other note to mention about using stars. The size input for billboard stars is relative to the size of the eventual texture output. The size input for point stars isn't. What that means to us is that the size of billboard stars will be the same, relative to the nebulas, no matter what resolution we choose to export at. The same is not true for point stars; their size is an absolute number of pixels. If we set a particular size for our point stars and export both a 512x512 image and a 4096x4096 image, we'll see a huge difference in the point stars between the two. That's why, when checking to see if point stars look the way we want, we always have to export an image at the final desired resolution. That's the only way to see how the point stars are actually going to look.