   Cel shading / outline.
  'lo, folks.I'm looking to add a style to my models where they keep their normal shading (either non-existent or typical shading) but also have a black outline.I've looked at the NeHe code and played with the example, but I'm not happy with the quality of the lines - even with antialiasing.So my question is... can anyone set me in the right direction for drawing a black outline (2-4px wide) on edges which actually looks good?Thanks in advance.   
  several methods that i know of... but the one i use when its required involves using edge detection on the mask of the object as a post process.let me know if you need more details... platform would be handy too (I'm a console programmer)   ;  Thanks for the reply.I'm using OpenGL on PC/Windows. Any suggestions would be helpful.   ;  Another option is to generate an edge mesh for your object. This gives you complete control over the look of your edge and allows you to texture brush strokes to give the mesh a sketched sort of look.Here's a link to some informationhttp://graphics.cs.brown.edu/games/FeatureEdges/index.html;  There are planty of techniques how to achieve outline / silhouette. Basically you can divide them into two groups : Geometry based and Post - Process Based.Geometry Base - techniques like rendering mesh backfaces slightly biased to form silhoutte. Other is called "shell mapping" (just google it).Post-Process - There are techniques to detect edges using normal maps, z-depth maps, Sobel Filter.You can find a lot of useful articles  in  NPR Rendering