Would be nice to be able to catch this with assert as well, will see what would
be the best way to do this/.\
Need to verify with Mai that this solves crash for her and maybe consider
porting this to 2.79.
Basically, make re-alloc and memcpy from the same lock, otherwise one
thread might be re-allocating thread while another one is trying to
copy data there.
Reported by Mohamed Sakr in IRC, thanks!
Since all the shadow catchers are already assumed to be in the footage,
the shadows they cast on each other are already in the footage too. So
don't just let shadow catchers skip self, but all shadow catchers.
Another justification is that it should not matter if the shadow catcher
is modeled as one object or multiple separate objects, the resulting
render should be the same.
Differential Revision: https://developer.blender.org/D2763
The idea is to make include statements more explicit and obvious where the
file is coming from, additionally reducing chance of wrong header being
picked up.
For example, it was not obvious whether bvh.h was refferring to builder
or traversal, whenter node.h is a generic graph node or a shader node
and cases like that.
Surely this might look obvious for the active developers, but after some
time of not touching the code it becomes less obvious where file is coming
from.
This was briefly mentioned in T50824 and seems @brecht is fine with such
explicitness, but need to agree with all active developers before committing
this.
Please note that this patch is lacking changes related on GPU/OpenCL
support. This will be solved if/when we all agree this is a good idea to move
forward.
Reviewers: brecht, lukasstockner97, maiself, nirved, dingto, juicyfruit, swerner
Reviewed By: lukasstockner97, maiself, nirved, dingto
Subscribers: brecht
Differential Revision: https://developer.blender.org/D2586
The issue here was mainly coming from minimal pixel width feature
which is quite commonly enabled in production shots.
This feature will use some probabilistic heuristic in the curve
intersection function to check whether we need to return intersection
or not. This probability is calculated for every intersection check.
Now, when we use multiple BVH nodes for curve primitives we increase
probability of that primitive to be considered a good intersection
for us. This is similar to increasing minimal width of curve.
What is worst here is that change in the intersection probability
fully depends on exact layout of BVH, meaning probability might
change differently depending on a view angle, the way how builder
binned the primitives and such. This makes it impossible to do
simple check like dividing probability by number of BVH steps.
Other solution might have been to split BVH into fully independent
trees, but that will increase memory usage of all the static
objects in the scenes, which is also not something desirable.
For now used most simple but robust approach: store BVH primitives
time and test it in curve intersection functions. This solves the
regression, but has two downsides:
- Uses more memory.
which isn't surprising, and ANY solution to this problem will
use more memory.
What we still have to do is to avoid this memory increase for
cases when we don't use BVH motion steps.
- Reduces number of maximum available textures on pre-kepler cards.
There is not much we can do here, hardware gets old but we need
to move forward on more modern hardware..
This way we can stop traversing BVH node early on.
Gives about 2-2.5x times render time improvement with 3 BVH steps.
Hopefully this gives no measurable performance loss for scenes with
single BVH step.
Traversal is currently only implemented for QBVH, meaning old CPUs
and GPU do not benefit from this change.
Similar to the previous commit, the statistics goes as:
BVH Steps Render time (sec) Memory usage (MB)
0 46 260
1 27 373
2 18 598
3 15 826
Scene used for the tests is the agent's body from one of the barber
shop scenes (no textures or anything, just a diffuse material).
Once again this is limited to regular (non-spatial split) BVH,
Support of spatial split to this feature will come later.
The idea is to create several smaller BVH nodes for each of the motion
curve primitives. This acts as a forced spatial split for the single
primitive.
This gives up render time speedup of motion blurred hair in the cost
of extra memory usage. The numbers goes as:
BVH Steps Render time (sec) Memory usage (MB)
0 258 191
1 123 278
2 69 453
3 43 627
Scene used for the tests is the agent's hair from one of the barber
shop scenes.
Currently it's only limited to scenes without spatial split enabled,
since the spatial split builder requires some changes to work properly
with motion steps coordinates.
This avoids intersection AABB of different curve primitives
which makes it less ray-to-primitive intersections.
This gives about 30% speedup of hair rendering in the barber
shop scenes here. There is still some work to be done on those
files to solve major speed issues on certain frames.
This way we can have different limits for regular and motion curves
which we'll do in one of the upcoming commits in order to gain some
percents of speedup.
The reasoning here is that motion curves are usually intersecting
lots of others bounding boxes, which makes it inefficient to have
single primitive in the leaf node.
Maximal number of elements is supposed to be inclusive. That is what
it was always meant in this file and what @brecht considered still
the case in 6974b69c6172.
In fact, the commit message to that change mentions that we allowed
up to 2 curve primitives per leaf while in fact it was doing up to 1
curve primitive.
Making it real 2 primitives at a max gives about 5% slowdown for the
koro.blend scene. This is a reason why BVHParams.max_curve_leaf_size
was changed to 1 by this change.
It was possible to have non-initialized unaligned BVH split
to be used when regular BVH split SAH was inf. Now we ensure
that unaligned splitter is only used when it's really initialized.
It's a regression and should be in 2.78a.
This reverts commit ecbfa31caaadb03c53c0fe1459718b99613c8804.
Original commit broke logic in nodes re-fitting. That area can
access non-existing children momentarely. Not sure what would
be best solution here, for now simply reverting the change/
The issue was caused by some false-positive empty non-AABB intersection.
Tried to tweak it a bit so it does not record intersection anymore.
Hopefully will work for all platforms. Tested here on iMac and Debian.
For proper indexing to work we need to use unaligned node with
identity transform instead of aligned nodes when doing refit.
To be backported to 2.78 release.
This is a special builder type which is allowed to orient nodes to
strands direction, hence minimizing their surface area in comparison
with axis-aligned nodes. Such nodes are much more efficient for hair
rendering.
Implementation of BVH builder is based on Embree, and generally idea
there is to calculate axis-aligned SAH and oriented SAH and if SAH
of oriented node is smaller than axis-aligned SAH we create unaligned
node.
We store both aligned and unaligned nodes in the same tree (which
seems to be different from what Embree is doing) so we don't have
any any extra calculations needed to set up hair ray for BVH
traversal, hence avoiding any possible negative effect of this new
BVH nodes type.
This new builder is currently not in use, still need to make BVH
traversal code aware of unaligned nodes.
This seems to be straightforward way to support heterogeneous nodes
in the same tree.
There is some penalty related on 4gig limit of the address space now,
but here's are the thing:
Traversal code was already using ints to store final offset, so
there can't be regressions really.
This is a required commit to make it possible to encode both aligned
and unaligned nodes in the same array. Also, in the future we can use
this to get rid of __leaf_nodes array (which is a bit tricky to do since
trickery in pack_instances().
There are several internal changes for this:
First idea is to make __tri_verts to behave similar to __tri_storage,
meaning, __tri_verts array now contains all vertices of all triangles
instead of just mesh vertices. This saves some lookup when reading
triangle coordinates in functions like triangle_normal().
In order to make it efficient needed to store global triangle offset
somewhere. So no __tri_vindex.w contains a global triangle index which
can be used to read triangle vertices.
Additionally, the order of vertices in that array is aligned with
primitives from BVH. This is needed to keep cache as much coherent as
possible for BVH traversal. This causes some extra tricks needed to
fill the array in and deal with True Displacement but those trickery
is fully required to prevent noticeable slowdown.
Next idea was to use this __tri_verts instead of __tri_storage in
intersection code. Unfortunately, this is quite tricky to do without
noticeable speed loss. Mainly this loss is caused by extra lookup
happening to access vertex coordinate.
Fortunately, tricks here and there (i,e, some types changes to avoid
casts which are not really coming for free) reduces those losses to
an acceptable level. So now they are within couple of percent only,
On a positive site we've achieved:
- Few percent of memory save with triangle-only scenes. Actual save
in this case is close to size of all vertices.
On a more fine-subdivided scenes this benefit might become more
obvious.
- Huge memory save of hairy scenes. For example, on koro.blend
there is about 20% memory save. Similar figure for bunny.blend.
This memory save was the main goal of this commit to move forward
with Hair BVH which required more memory per BVH node. So while
this sounds exciting, this memory optimization will become invisible
by upcoming Hair BVH work.
But again on a positive side, we can add an option to NOT use Hair
BVH and then we'll have same-ish render times as we've got currently
but will have this 20% memory benefit on hairy scenes.
It was initially unsupported because initial idea of checking visibility
of all children was slowing scenes down a lot. Now the idea has changed
and we only perform visibility check of current node. This avoids huge
slowdown (from tests here it seems to be withing 1-2%, but more tests
would never hurt) and gives nice speedup of ray traversal for complex
scenes which utilized ray visibility.
Here's timing of koro.blend:
Without visibility check With visibility check
Original file 4min 20sec 4min 23sec
Camera rays only 1min 43 sec 55sec
Unfortunately, this doesn't come for free and requires extra data in
BVH node, which increases memory usage of BVH nodes by 15%. This we
can solve with some future trickery of avoiding __tri_storage created
for curve segments.
