Real world examples:
Here are some photos of real world glass sculptures with facing panels.
Author: Vaclav Cigler
What options do we have?:
All testing will be done on simple scene with glass sculpture composed from 3 glass blocks. Material used is Brazil2 Glass material with enabled absorbtion (light blue).
Option 1 - Facing panels
At fist we can let the geometry as we have modeled it. Less work for us but causes artifacts from some angles due to Coincident Faces Crud.Option 2 - Intersecting panelsDrawbacks: causes erros due to Coincident Faces Crud
What will happen if we will try to slightly intersect the panels? This will let us to get rid of artifacts and may look like right solution. But the refractions/reflections will be inacurate due to fact that in real world this can´t be done and we are making additional interractions.Benefits: no errors from Coincident Faces CrudDrawbacks: inacurate reflections/refractions
Option 3 - Gap between panels
In real world if the glass panels aren´t baked together there still remains some small gap filled with air/other interface (glue...etc.) between them. So when we offset the panels with leaving a small space between them we should get the right result by simulating this fenomen.Benefits: no errors, acurate reflections/refractionsDrawbacks: moving with the modelI hope that this simple demonstration will help to those who has problems with this part of glass objects rendering. Any additional ideas or contributions are wellcome and I´ll add them into article.Pavel Romsy
Michelle Bivotti 3D visualization