Hi Roland,
Those heads look great, and I have a new-found respect for smooth heads: I went looking at a bunch of minifig/starwars heads with my smoothing code and saw a lot of artifacts like your previous pictures. T junctions, non-water-tight connections, transforms...it's a jungle out there. :-)
I was going to mention this in response to "other ideas" but re: the meta command.
There is a totally different approach we could take, which would be consistent with the 3-d industry: we could write normal vectors into the LDraw files themselves.
This would mean that any smooth surface could have normals matching its underlying geometric shape, regardless of what that shape is. A smooth center meta command solves the problem for one shape, but then we'll need cylinders, cones, etc. Some shapes may be complex composites for which a pile of meta commands to get mathematically correct normals becomes quite painful.
Per-triangle and per-quad normals would cut down on the processing time to load a smooth part, and it would cut down (completely) on variance between implementations - we'd use the processed normals "as is". :-)
Such a scheme need not be ubiquitous - I am _not_ proposing any given syntax, but as a stupid straw-man example, we could have a meta command that, when preceding a triangle, sets the normals for that triangle. This would allow authors to "spot fix" particularly tricky cases like minifig heads, while leaving the simpler cases (cones, studs, etc.) up to the automatic algorithms. We could even code one of the apps to save out smoothed shapes _with_ the normal metas to act as a seed for authors who want to then tune smoothing.
Stepping back a little bit, I would like to see a system that:
1. Does not rely too heavily on heuristics to 'guess' what the author meant and
2. Provides ways for the author to specify exact behavior when needed without too much difficulty.
My concern about "heavy guessing" with 1 is that a complicated heuristic may produce wrong results such that the 'fix' introduces other wrong results. Better to have 2 - a system where authors can spend a little bit of time and get exact results when desired.
This is why I like rules like:
- Two triangles with exact matched corners and an angle > 60 degrees _will _be creased.
- Two triangles with exact corners and a line covering those corners exactly _will_ be creased.
It's easy to use the rules, straight forward to code, etc.
cheers
Ben
Those heads look great, and I have a new-found respect for smooth heads: I went looking at a bunch of minifig/starwars heads with my smoothing code and saw a lot of artifacts like your previous pictures. T junctions, non-water-tight connections, transforms...it's a jungle out there. :-)
I was going to mention this in response to "other ideas" but re: the meta command.
There is a totally different approach we could take, which would be consistent with the 3-d industry: we could write normal vectors into the LDraw files themselves.
This would mean that any smooth surface could have normals matching its underlying geometric shape, regardless of what that shape is. A smooth center meta command solves the problem for one shape, but then we'll need cylinders, cones, etc. Some shapes may be complex composites for which a pile of meta commands to get mathematically correct normals becomes quite painful.
Per-triangle and per-quad normals would cut down on the processing time to load a smooth part, and it would cut down (completely) on variance between implementations - we'd use the processed normals "as is". :-)
Such a scheme need not be ubiquitous - I am _not_ proposing any given syntax, but as a stupid straw-man example, we could have a meta command that, when preceding a triangle, sets the normals for that triangle. This would allow authors to "spot fix" particularly tricky cases like minifig heads, while leaving the simpler cases (cones, studs, etc.) up to the automatic algorithms. We could even code one of the apps to save out smoothed shapes _with_ the normal metas to act as a seed for authors who want to then tune smoothing.
Stepping back a little bit, I would like to see a system that:
1. Does not rely too heavily on heuristics to 'guess' what the author meant and
2. Provides ways for the author to specify exact behavior when needed without too much difficulty.
My concern about "heavy guessing" with 1 is that a complicated heuristic may produce wrong results such that the 'fix' introduces other wrong results. Better to have 2 - a system where authors can spend a little bit of time and get exact results when desired.
This is why I like rules like:
- Two triangles with exact matched corners and an angle > 60 degrees _will _be creased.
- Two triangles with exact corners and a line covering those corners exactly _will_ be creased.
It's easy to use the rules, straight forward to code, etc.
cheers
Ben