Age | Commit message (Collapse) | Author |
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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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Self-explanatory. to find broken links run `sphinx-build -b linkcheck sphinx-in sphinx-out`
Reviewers: mont29
Tags: #bf_blender, #python, #infrastructure:_websites
Differential Revision: https://developer.blender.org/D2297
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This setting can also be animated, to create a "time warp" effect.
D2122 by @LucaRood
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The way cloth is coded, structural springs are only effective when stretched, while bending springs act only when shrunk. However, when cloth is exactly in its rest shape, neither have any effect, and effectively don't exist for the implicit solver.
This creates a stability problem in the initial frames of the simulation, especially considering that gravity seems to act so precisely that it doesn't disturb the strict equality of lengths, so in parts of the cloth this springless state can continue for quite a while.
Here is an example of things going haywire because of this and some suspicious logic in collision code acting together: {F314558}
Changing the condition so that structural springs are active even at exactly rest length fixes this test case. The use of >= is also supported by the original paper that the cloth implementation in blender is based on.
Reviewers: lukastoenne
Reviewed By: lukastoenne
Projects: #bf_blender
Differential Revision: https://developer.blender.org/D2028
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Actually, it was the whole 'cloth' simulation of hairs that was broken,
since grid data could not be initialized correctly.
Stupid mistake from looptri conversion, rBc582e186d90291a19a4e404111c492f1fd2c41a4
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Also added a DEBUG_TIME macro in the related files to comment time funcs out.
Reviewers: brecht
Reviewed By: brecht
Subscribers: brecht
Differential Revision: https://developer.blender.org/D1717
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While SCons building system was serving us really good for ages it's no longer
having much attention by the developers and started to become quite a difficult
task to maintain.
What's even worse -- there started to be quite serious divergence between SCons
and CMake which was only accumulating over the releases now. The fact that none
of the active developers are really using SCons and that our main studio is also
using CMake spotting bugs in the SCons builds became quite a difficult task and
we aren't always spotting them in time.
Meanwhile CMake became really mature building system which is available on every
platform we support and arguably it's also easier and more robust to use.
This commit includes:
- Removal of actual SCons building system
- Removal of SCons git submodule
- Removal of documentation which is stored in the sources and covers SCons
- Tweaks to the buildbot master to stop using SCons submodule
(this change requires deploying to the server)
- Tweaks to the install dependencies script to skip installing or mentioning
SCons building system
- Tweaks to various helper scripts to avoid mention of SCons folders/files
as well
Reviewers: mont29, dingto, dfelinto, lukastoenne, lukasstockner97, brecht, Severin, merwin, aligorith, psy-fi, campbellbarton, juicyfruit
Reviewed By: campbellbarton, juicyfruit
Differential Revision: https://developer.blender.org/D1680
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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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Also 'com' as abbreviation for center-of-mass is a bit confusing, rename to 'center'.
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Also add depsgraph & physics
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This reverts commit 4c723eb80e299eb6ca11ad72b5fcbe8746c4a854.
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as complicated as before cloth solver changes.
Still doesn't solve the collapsing cloth cube issue mentioned in T43406,
probably the bending springs work somewhat differently now.
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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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This was disabled during the course of hair dynamics work. The cloth
collision solution is based on a secondary velocity-only solver step.
While this approach is usable in general, the collision response
calculation still does not work well for hair meshes. Better contact
point generation is needed here (Bullet) and preferably an improved
solver for unilateral constraints.
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These were used as UI buttons during development. If such parameters are
needed again later they should instead be added in the (now global)
SimDebugData and made accessible with a dev addon or so.
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This way it doesn't have to be stored as DNA runtime pointers or passed
down as a function argument. Currently there is now no property or
button to enable debugging, this will be added again later.
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Cloth data is used both for hair and actual cloth, which makes things
really difficult. The face number was used for distinguishing the two
types (no faces == hair mesh), but the extra hair data necessary for
hair sim is generated by particles and not available for edge-only cloth
meshes. This really needs to be sanitized ...
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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approach does not work very well.
Using a cross section estimate still causes large oscillations due to
varying hair force based on angles. It also requires a sensible hair
thickness value (particle radius) which is difficult to control and
visualize at this point.
The new model is based purely on per-vertex forces, which seems to be
much more stable. It's also somewhat justified by the fact that each
hair vertex represents a certain mass.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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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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A stupid hack is needed here, changing the way the factor is applied to
angular bending springs. In cloth sim the bending factor of individual
springs is applied as a mix value between the bending stiffness and a
max value, but this max value isn't even used in hair sim so that
approach becomes useless.
Conflicts:
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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to support multiple hash identifiers.
Using explicit hashing functions for every sim debug call defeats the
purpose of having a quick feedback system. Now this can be done simply
by passing an arbitrary number of hash inputs (integers) at the end of
the function calls, which are then combined by a system of variadic
macros (based on the ELEM feature). Up to 8 identifiers are supported
currently, but more could be added easily if needed.
Conflicts:
source/blender/blenkernel/intern/particle_system.c
source/blender/physics/intern/BPH_mass_spring.cpp
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density factor (already included in grid velocity).
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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needs to be substracted instead.
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other values.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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The Eigen solver for hair grids uses an extra margin of 1, which means
greater stride values.
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zero vectors, leading to bad density values.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
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solver input and output.
This uses the central difference method (instead of combined forward/
backward difference), which makes it easier to correctly account for
grid borders.
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