Age | Commit message (Collapse) | Author |
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2.8x branch added bContext arg in many places,
pass eval-context instead since its not simple to reason about what
what nested functions do when they can access and change almost anything.
Also use const to prevent unexpected modifications.
This fixes crash loading files with shadows,
since off-screen buffers use a NULL context for rendering.
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Note that some little parts of code have been dissabled because eval_ctx
was not available there. This should be resolved once DerivedMesh is
replaced.
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This removes the goal springs, in favor of simply calculating the goal forces on the vertices directly. The vertices already store all the necessary data for the goal forces, thus the springs were redundant, and just defined both ends as being the same vertex.
The main advantage of removing the goal springs, is an increase in flexibility, allowing us to much more nicely do some neat dynamic stuff with the goals/pins, such as animated vertex weights. But this also has the advantage of simpler code, and a slightly reduced memory footprint.
This also removes the `f`, `dfdx` and `dfdv` fields from the `ClothSpring` struct, as that data is only used by the solver, and is re-computed on each step, and thus does not need to be stored throughout the simulation.
Reviewers: sergey
Reviewed By: sergey
Tags: #physics
Differential Revision: https://developer.blender.org/D2514
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This adds the ability for cloth simulations to respect changes in the underlying mesh.
So you can for instance, animate shape keys, armatures, or add any deformation modifiers (above the cloth modifier).
This is mainly useful for (but not limited to) cartoon animations,
where your character might stretch or change shape, and you want the clothes to follow accordingly.
D1903 by @LucaRood
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Originally the value was only needed when building the springs,
so a pointer to the input data was somewhat ok. However, recalculating
spring length dynamically requires keeping the actual value around.
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Note that the collision modifier doesn't have any use for Loop indices,
so to avoid duplicating the loop array too,
MVertTri has been added which simply stores vertex indices (runtime only).
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This method does not work for hair anyway. Even though hair collision
needs work at this point, it's still better than nothing.
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The previous calculation was modulated with the angle between the wind
direction and the segments, which leads to very oscillating behavior.
Now the formula includes an estimate for the geometric cross section
of a hair segment based on the incident angle and the hair thickness
(currently just the particle size). This gives a more stable behavior
and more realistic response to wind.
Conflicts:
source/blender/blenkernel/intern/particle_system.c
source/blender/physics/intern/BPH_mass_spring.cpp
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This helps to create some variation in a hair system, which can
otherwise become very uniform and boring. It's yet another confusing
setting in a system that should have been nodified, but only option for
now (broken windows ...)
Conflicts:
source/blender/blenkernel/intern/particle_system.c
source/blender/physics/intern/BPH_mass_spring.cpp
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one solver anyway), and split some particle cloth functions for clarity.
Conflicts:
source/blender/blenkernel/BKE_particle.h
source/blender/blenkernel/intern/particle_system.c
source/blender/blenloader/intern/versioning_270.c
source/blender/makesdna/DNA_particle_types.h
source/blender/makesrna/intern/rna_particle.c
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This is not necessary: the implicit solver data can keep track instead
of how many off-diagonal matrix blocks are in use (provided the
allocation limit is calculated correctly). Every time a spring is
created it then simply increments this counter and uses the block index
locally - no need to store this persistently.
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Basically follows the Pixar approach from "Artistic Simulation of Curly
Hair".
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This is more involved than using simple straight bending targets
constructed from the neighboring segments, but necessary for restoring
groomed rest shapes.
The targets are defined by parallel-transporting a coordinate frame
along the hair, which smoothly rotates to avoid sudden twisting (Frenet
frame problem). The rest positions of hair vertices defines the target
vectors relative to the frame. In the deformed motion state the frame
is then recalculated and the targets constructed in world/root space.
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derivatives for stabilization.
The bending forces are based on a simplified torsion model where each
neighboring point of a vertex creates a force toward a local goal. This
can be extended later by defining the goals in a local curve frame, so
that natural hair shapes other than perfectly straight hair are
supported.
Calculating the jacobians for the bending forces analytically proved
quite difficult and doesn't work yet, so the fallback method for now
is a straightforward finite difference method. This works very well and
is not too costly. Even the original paper ("Artistic Simulation of
Curly Hair") suggests this approach.
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This returns a general status (success/no-convergence/other) along with
basic statistics (min/max/average) for the error value and the number
of iterations. It allows some general estimation of the simulation
quality and detection of critical settings that could become a problem.
Better visualization and extended feedback can follow later.
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These are much better suited for creating stiff hair. The previous
bending springs are based on "push" type spring along the hypothenuse
of 3 hair vertices. This sort of spring requires a very large force
in the direction of the spring for any angular effect, and is still
unstable in the equilibrium.
The new bending spring model is based on "target" vectors defined in a
local hair frame, which generates a force perpendicular to the hair
segment. For further details see
"Artistic Simulation of Curly Hair" (Pixar technical memo #12-03a)
or
"A Mass Spring Model for Hair Simulation" (Selle, Lentine, Fedkiw 2008)
Currently the implementation uses a single root frame that is not yet
propagated along the hair, so the resulting rest shape is not very
natural. Also damping and derivatives are still missing.
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create/free functions for solver data off from the cloth solver.
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code.
The implicit solver itself should remain agnostic to the specifics of
the Blender data (cloth vs. hair). This way we could avoid the bloated
data conversion chain from particles/hair to derived mesh to cloth
modifier to implicit solver data and back. Every step in this chain adds
overhead as well as rounding errors and a possibility for bugs, not to
speak of making the code horribly complicated.
The new subfolder is named "physics" since it should be the start of a
somewhat "unified" physics systems combining all the various solvers in
the same place and managing things like synchronized time steps.
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some coordinate transform issues.
Collision response should be regarded as part of the dynamics system
instead of the basic collision detection.
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This will allow us to implement moving reference frames for hair and
make "fictitious" forces optional, aiding in creating stable and
controllable hair systems.
Adding data in this place is a nasty hack, but it's too difficult to
encode as a DM data layer and the whole cloth modifier/DM intermediate
data copying for hair should be removed anyway.
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responses.
The S matrix together with the z Vector encodes the degrees of freedom
of a colliding hair point and the target velocity change. In a collision
the hair vertex is restricted in the normal direction (when moving
toward the collider) and the collision dynamics define target velocity.
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Instead of handling contact tests and collision response in the same
function in collision.c, first generate contact points and return them
as a list, then free at the end of the stepping function. This way the
contact response can be integrated into the conjugate gradient method
properly instead of using the hackish and unstable double evaluation
that is currently used.
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This is still using the old BVH tree collision methods to generate
contact points, similar to what cloth does. This should be replaced
by a Bullet collision check, but generating contacts in this way is
easier for now, and lets us test responses and stability (although in
more complex collision cases the BVH method fails utterly, beside being
terribly inefficient with many colliders).
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structure as a texture.
This is mostly a debugging feature that may be removed again later.
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Description:
--------------------------
Use loose edges marked as seams as sewing springs.
Usage:
-------------------------
All this patch does is set the rest length to 0 and the stiffness to 1 for springs for loose edges marked as seams so that during the cloth simulation they will be brought together.
Example Video:
-------------------------
http://www.youtube.com/watch?v=-Y_bC0gjoM0
Original Patch by thesleepless (+ git patch by codemanx)
Thank you!
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- was ordering vertex args unnecessarily.
- was adding the same edges multiple times into the edgehash.
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unused defines and correct include guards.
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Fix 1: Pinned vertices were never released when "unpinned" by Dynamic Paint.
Fix 2: When pinning vertices during simulation, they would get "warped" to their original starting position of frame 1.
Thanks to MiikaH for pointing this out and also for providing the regression blend file: http://wiki.blender.org/uploads/a/ab/Cloth_dynamic_paint.blend
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Self collision vertex groups enable artists to exclude selected vertices from getting involved in self collisions. This speeds simulations and it also resolves some self collision issues.
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People: Better use subsurf after cloth since you can get failing collisions otherwise!
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- Triangulate Cloth Mesh for collisions
- Speed up collisions
- Remove EL Topo code
- Prepare code to incooperate El Topo self collisions (TODO next commits)
TODO:
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- Triangulation: Is custom data/uv preserved correctly?
- Use MPoly not tessface?
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between 'var[num]')
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added some missing functions too - which are not used yep but should be there for api completeness.
* CDDM_set_mloop
* CDDM_set_mpoly
* BLI_mempool_count
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without the underscores these clogged up the namespace for autocompleation which was annoying.
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Make Cloth modifier deformation only so now it applies on orco dm properly.
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Calculate cloth and softbody only for single frame time deltas
(like it's already done for smoke)
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http://markmail.org/message/fp7ozcywxum3ar7n
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Recommitted eltopo collision code (but disabled by default)
with Genscher's permission.
To use, you need to install liblapack and libblas
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'const char's,.
Only one functional change where Transform orientations passed "" to BIF_createTransformOrientation() which could then have the value written into.
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