They are now generated by a build.rs script from nothing but the
colorspace's primaries, which makes it super easy to add more
colorspaces. So easy that I added three more: ACES AP0, ACES AP1
and Rec.2020.
This lays the foundation for supporting output to different
colorspaces.
This eliminates writing temp files to disk for any part of the
Blender/Psychopath integration.
The option to export to a file still exists, however, by
specifying an export output path.
This is more a piece-of-mind thing than anything else. But it
also lets us make the number of LDS dimensions lower without
worrying, which in turn makes the code smaller.
After implementation, it does appear to make rendering slower
by a noticable bit compared to what I was doing before. At very
low sampling rates it does provide a bit of visual improvement,
but by the time you get to even just 16 samples per pixel its
benefits seem to disappear.
Due to the slow down and the minimal gains, I'll be removing
this in the next commit. But I want to commit it so I don't
lose the code, since it was an interesting experiment with
some promising results.
I couldn't make the BVH4 faster than the BVH, and the bitstack
was bloating the AccelRay struct. Removing the bitstack gives
a small but noticable speedup in rendering.
Specifically, LightPath is now significantly smaller, and
resultingly faster to process.
Also finally fixed the bug where without light sources the light
from the sky wouldn't affect surfaces.
If the average surface area of all the time samples is close enough
to the surface area of their union, just take the union and use that.
This both makes the BVH smaller in memory (time samples don't
propigate up the tree beyond their usefulness) and makes it
faster since traversal can avoid interpolating BBoxes when there's
only one BBox for a node.
Reduced from 64 to 42. This still allows each BVH to hold 4.4
trillion elements, but it guarantees that the accel ray's
traversal bitstack can accommodate at least two nested max-depth
trees.
In practice it worked fine, but only by accident. NaN's were
being passed to the lerp_slice function, which led to the
correct result in this case but is icky and dependant
on how lerp_slice is implemented.
The BVH building code is now largely split out into a separate
type, BVHBase. The intent is that this will also be used by
the BVH4 when I get around to it.
The BVH itself now uses references instead of indexes, allocating
and pointing directly into the MemArena. This allows the nodes
to all be right next to their bounding boxes in memory.
This seems to work more nicely than a fixed block size, because
it adapts to how much memory is being requested over-all. For
example, a small scene won't allocate large amounts of RAM,
but a large scene with large data won't be penalized with a
lot of tiny allocations.
Not tested yet, just a straightforward conversion from the C++
Psychopath codebase. So there are probably bugs in it from the
conversion. But it compiles!
Also created a proper World struct in the process, to store all
infinite-extent type stuff.
Note that I goofed and did a new rustfmt pass but forgot to
commit before making these changes, so there's a lot of
formatting changes in this too. *sigh*
After some experimentation, it's pretty clear that the LightTree
performs a lot better with a model of spherical _volume_ light
sources. This makes sense considering that generally they
represent a distribution of other lights in space.
This is a quick hack to make it behave a bit more like that. But
the long-term solution will be to adjust how
estimate_eval_over_solid_angle() of surface closures is implemented.
Turns out that the standard min/max functions were slow for
some reason, and simple if statements are much faster. This
simple change improves render times by over 30%. Crazy.
The bug was in the previous commit, where I thought I was
preventing out-of-bounds access during traversal by limiting
the tree depth. While the idea was correct, I forgot that the
traversal stack needs _2_ extra slots on top of the tree depth,
not just 1. Fixed.
This avoids exceeding max BVH depth even in pathological cases.
Still need improve non-worst case building, but this at least
prevents crashes in worst case.
