How would you draw the outline of a 3D object? (Like being selected.) I guess it can be done with the ColorBlendAttrib, but I haven’t used it ever.
I think the ColorBlendAttrib ( panda3d.org/apiref.php?page=ColorBlendAttrib )
is severly underdocumented, and the manual doesn’t even mentions it.
There is a sample on cartoon inking.
Also, an easy trick can be to make a copy of the model, draw it inside-out with a scale of 1.001 or so and with the colour of the outline colour that you wanted.
Another approach would be to render a mask to a buffer, blurring that, and then thresholding that (the value would determine the thickness) and blending it on top of the scene. You can use the FilterManager for this.
I guess I need to read the render-to-texture part of the docs.
You can use the higher-level FilterManager or CommonFilters interface.