问题
I've been making a game in scene kit, but the edges of objects are difficult to see, making some of the games details impossible to see. Is there a way to make a black outline around all the game objects?
回答1:
you could use an SCNTechnique as mentioned in another answer (you can have a look at this article about cel shading, which has an edge-detection pass) but full-frame post-processes are quite expensive.
On OS X you can also leverage geometry shaders (see this article). But it's not available on iOS and might be harder to implement and get right.
I would go with a much easier technique, which only involves vertex and fragment shaders. You can take a look at this article, which gives an example that's easy to re-create in SceneKit using SCNProgram or shader modifiers.
回答2:
There is an example of making a glowing outline for nodes that uses SCNTechnique here: https://github.com/laanlabs/SCNTechniqueGlow
You could modify the color and blur method to achieve an stroked outline effect.
回答3:
Another SCNTechnique example, as referenced here: https://www.nurfacegames.com/everything-you-wanted-to-know-about-outline-shaders/, is to render your node slightly larger behind then again in front at regular size.
Here's a playground example of that: https://github.com/mackhowell/scenekit-outline-shader-scntechnique.
来源：https://stackoverflow.com/questions/29665700/is-there-a-way-to-add-an-outline-in-scene-kit