You can use shadow_volume_test example program in engine sources (look in subdirectory kambi_vrml_game_engine/3dmodels.gl/examples/shadow_volume_test/). This allows you to test various shadow volume algorithm variations. Also you can see how silhouette edge detection goes, which edges from ManifoldEdges (2 neighbors) are qualified as silhouette and which edges were detected as BorderEdges.

Figure 7.1. Fountain level, no shadows

Figure 7.2. Fountain level, shadows turned on

Now, turn edges on. Silhouette edges detected are drawn yellow (these depend on light position relative to the model). Blue edges are BorderEdges (these are independent from light position, they are simply edges with only 1 neighbor triangle).

Figure 7.3. Fountain level, edges marked

Figure 7.4. Fountain level, only edges