>
> Probably a good time to revisit the big picture now that there’s more
> familiarity with terminology:
> http://brlcad.org/wiki/Density_functions
> <http://brlcad.org/wiki/Density_functions>
> http://brlcad.org/wiki/Material_and_Shader_Objects
> <http://brlcad.org/wiki/Material_and_Shader_Objects>
>
> Should we try to put our new density structure inside the .g database
> directly? This can be delayed until things start working and we know how we
> are gonna store our data but it would definitely kill two birds with one
> stone.
After it’s working, that’s the next logical step. Don’t want to scope-creep
the complexity prematurely, but we will eventually want material objects
defining the density (and other) material characteristics of an object (as a
replacement for .density files and _DENSITY objects).
> If we let the user define a "base" density (lets say at the origin or
> something) then 1 point would already mean a vector (from origin to that
> point, forming a gradient). If we don't do it, then 0 points make no sense
> since we would have no density information at all, right?
The point of 0 points (hah) first is just to make sure the full range is
covered. Someone will eventually figure out a way to set/delete/create 0
points and the code should handle the edge case gracefully, sensibly.
I don’t think we want to create some implicit behavior that we’d have to
document somewhere. If there’s only one density point, it emanates outwards in
all directions (i.e., a constant field). That’s not unlike the current
material ID value which sets the density. The main consideration would be
defining what does a density point outside the model means.
For 2 points, it’s a simple vector from one to the other (a basic gradient).
> I think we can already handle up to three vectors since it would mean
> applying what we drafted in the examples I sent previously. Basically
> calculating contributions and joining them (using average for now, more
> complex methods in the future).
They can be handled only if the bounding volume does not contain any interior
points. If there are interior points, like your example of a rod with density
going up/down, it’s going to be different (and that’s what was deferred for
later, to not waste time on the most complex general case).
Cheers!
Sean
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