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.
This allows setting a target density which the fluid simulation will
take into account as an additional term in the pressure Poisson
equation. Based on two papers
"Detail Preserving Continuum Simulation of Straight Hair" (McAdams et al. 2009)
and
"Two-way Coupled SPH and Particle Level Set Fluid Simulation" (Losasso et al. 2008)
Currently the target pressure is specified directly, but it will be
a lot more convenient to define this in terms of a geometric value such
as "number of hairs per area" (combined with hair "thickness").
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
This is a bit more awkward for artists to use, but necessary for
a stable solution of the hair continuum calculation. The grid size is
defined by the user, the extent of the grid is then calculated based on
the hair geometry. A hard upper limit prevents bad memory allocation
in case too small values are entered.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
This is an artifact of earlier attempts to implement velocity smoothing,
but doesn't work anyway.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
This is part of the original method from "Volumetric Methods for
Simulation and Rendering of Hair". The current filter is a simple box
filter. Other energy-preserving filters such as gaussian filtering
can be implemented later.
The filter size is currently given as a cell count. This is not ideal,
rather it should use a geometrical length value, but this is too
abstract for proper artistical use. Eventually defining the whole grid
in terms of spatial size might work better (possibly using an external
object).
This implements a penalty force as well as a repulsion force to avoid
further penetration, as suggested in
"Simulating Complex Hair with Robust Collision Handling"
(http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf)
Friction forces are still missing. More problematic is handling of
moving colliders, when face swap places with the hair vertex and a
collision is missed, putting the vertex inside the mesh volume. Larger
margins might help, but ultimately using Bullet collision detection is
probably more reliable and failsafe.
on itself.
This uses the same voxel structure as the hair smoothing algorithm.
A slightly different method was suggested in the original paper
(Volumetric Methods for Simulation and Rendering of Hair), but this is
based on directing hair based on a target density, which is another
way of implementing global goals. Our own approach is to define a
pressure threshold above which the hair is repelled in the density
gradient direction to simulate internal pressure from collisions.
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!
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.
to specify different spring lengths.
Implementation is quite ugly because the shape key has to be pulled
through the modifier stack somehow, need a more flexible data mask
system to solve this properly.
(commits 27773,27775,27778 by Brecht from render25 branch)
* Effectors now work with hair dynamics.
* Hair dynamics has a new "Collider Friction" parameter that works similarly to internal friction except now all collision objects effect the hair velocity. Useful for quick'n'dirty interaction with objects as the calculations are really fast, but doesn't really take away the need for proper hair-object collisions.
struct members "gravity" and "[3]". Now it throws an error in this case,
safer than trying to fix the parsing code. Also patches the old DNA of
ClothSimSettings which had this problem .. very ugly code.
Fixes#20330: cloth sim settings getting corrupted when read from 2.49.
* structural can be set to 0
* pre-roll now available through GUI and works like following:
a) Pre rolled frames are NOT cached
b) reset cache + cloth on pre roll setting change
* Unified scene wide gravity (currently in scene buttons)
instead of each simulation having it's own gravity.
* Weight parameters for all effectors and an effector group
setting.
* Every effector can use noise.
* Most effectors have "shapes" point, plane, surface, every point.
- "Point" is most like the old effectors and uses the
effector location as the effector point.
- "Plane" uses the closest point on effectors local xy-plane
as the effector point.
- "Surface" uses the closest point on an effector object's
surface as the effector point.
- "Every Point" uses every point in a mesh effector object
as an effector point.
- The falloff is calculated from this point, so for example
with "surface" shape and "use only negative z axis" it's
possible to apply force only "inside" the effector object.
* Spherical effector is now renamed as "force" as it's no longer
just spherical.
* New effector parameter "flow", which makes the effector act as
surrounding air velocity, so the resulting force is
proportional to the velocity difference of the point and "air
velocity". For example a wind field with flow=1.0 results in
proper non-accelerating wind.
* New effector fields "turbulence", which creates nice random
flow paths, and "drag", which slows the points down.
* Much improved vortex field.
* Effectors can now effect particle rotation as well as location.
* Use full, or only positive/negative z-axis to apply force
(note. the z-axis is the surface normal in the case of
effector shape "surface")
* New "force field" submenu in add menu, which adds an empty
with the chosen effector (curve object for corve guides).
* Other dynamics should be quite easy to add to the effector
system too if wanted.
* "Unified" doesn't mean that force fields give the exact same results for
particles, softbody & cloth, since their final effect depends on many external
factors, like for example the surface area of the effected faces.
Code changes
* Subversion bump for correct handling of global gravity.
* Separate ui py file for common dynamics stuff.
* Particle settings updating is flushed with it's id through
DAG_id_flush_update(..).
Known issues
* Curve guides don't yet have all ui buttons in place, but they
should work none the less.
* Hair dynamics don't yet respect force fields.
Other changes
* Particle emission defaults now to frames 1-200 with life of 50
frames to fill the whole default timeline.
* Many particles drawing related crashes fixed.
* Sometimes particles didn't update on first frame properly.
* Hair with object/group visualization didn't work properly.
* Memory leaks with PointCacheID lists (Genscher, remember to
free pidlists after use :).
- Hair dynamics have their own panel in particle settings with the settings from cloth panel that apply to hair.
- Basic internal friction force to quickly emulate self collisions and volume preservation. (Still very early code, but gives some idea of what's possible).
- Softbody simulation is no longer used for hair.
* Old files with sb dynamics should just load the hair without dynamics so new dynamics can be applied.
* Invasion of particles exceptions in sb code is finally over.
- Collisions with other objects are disabled for now and will be worked out in the future.
Other changes/fixes:
- Particle mode editing flag wasn't saved properly.
- Some old files with edited hair didn't load correctly.
- Disabled delete & specials menu in particle mode for non-hair editing.
- Fixed yet one more cloth & softbody pointcache update issue.
- Disconnect/connect hair now uses only the deformed mesh so it works correctly also for subsurfed emitters.
- Hair editing now updates correctly with a moving emitter.
* DNA_cloth_types.h, patch by Roelf de Kock. The gravity[3] member
is not being parsed correct by makesdna.c and will give issues
even when trying to fix it. Worked around it for now in RNA by
wrapping it manually, but this should really be fixed in the DNA
genetics code, added a comment about it in DNA_cloth_types.h.
* Handle vertex groups and uv layers more consistent now. They are
all exposed as strings now. Reason is that indices don't really
say much, and a direct pointer is not always possible because for
example a uv layer in a material can be used for multiple objects
and so there is no single pointer. In python it is not too hard
to use either since the strings works as a key for lookups.
For the user interface we can later think of some method to
generate popup menus in a way that works for vertex groups,
uv layers, bones etc.
* This also fixes the XXX's in rna_modifier.c, I think that can be
marked done.
=======================
Caching and Baking:
- The point cache is now cleared on DAG_object_flush_update(), and not cleared for time dependency graph updates.
- There is now a Bake button instead of Protect. Also cache start and end frames were added to softbody and particles.
- The cloth autoprotect feature was removed.
- The Ctrl+B menu now also bakes cloth and particles next to softbody and fluids. Additionally there are now frree bake and free cache menu entries.
- The point cache api has been changed. There is now a PTCacheID struct for each point cache type that can be filled and then used to call the point cache functions.
- PointCache struct was added to DNA and is automatically allocated for each physics type.
- Soft body now supports Bake Editing just like cloth.
- Tried to make the systems deal consistently with time ipo's and offsets. Still not sure it all works correct, but too complicated to solve completely now.
Library Linking:
- Added some more warnings to prevent editing settings on library linked objects.
- Linked objects now read from the cache located next to the original library file, and never write to it. This restores old behavior for softbodies. For local simulation the mesh and not the object should be linked.
- Dupligroups and proxies can't create local point caches at the moment, how to implement that I'm not sure. We probably need a proxy point cache for that to work (ugh).
Physics UI:
- Renamed deflection panel to collision for consistency and reorganized the buttons. Also removed some softbody collision buttons from the softbody panel that were duplicated in this panel for cloth.
- Tweaked field panel buttons to not jump around when changing options.
- Tabbing e.g. Soft Body Collision into the Soft Body panel, it now only shows Collision to make the panel names readable.
- I tried to make enabled/disabling physics more consistent, since all three system did things different. Now the two modifier buttons to enable the modifier for the viewport and rendering are also duplicated in the physics panels. Toggling the Soft Body and Cloth buttons now both remove their modifiers.
- Fixed modifier error drawing glitch.
Particles:
- Particles are now recalculated more often than before. Previously it did partial updates based on the changes, but that doesn't work well with DAG_object_flush_update() ..
- Fixed memory leak loading keyed particle system. Now keys are not written to file anymore but always created after loading.
- Make particle threads work with autothreads.
Continue Physics:
- The timeline play now has a Continue Physics option in the playback menu, which keeps the simulations going without writing them to the cache.
- This doesn't always work that well, some changes are not immediately updated, but this can be improved later. Still it's fun to get a feel for the physics.
Todo:
- Point cache can get out of sync with and undo and changing a file without saving it.
- Change the point cache file format to store a version (so old point cache files can be either converted or at least ignored), and to do correct endian conversion.
- Menu item and/or buttons for Ctrl+B.
- A system("rm ..") was changed to remove() since the former is very slow for clearing point caches. These system() calls were already giving trouble in a bug in the tracker, but really most use of this system("") should be changed and tested.
- The Soft Body Collision and Clot Collision panel titles don't mention there's point cache settings there too, doing that makes them unreadable with the default panel setup.. but may need to make the names longer anyway.
Lukas Tönne
Daniel Genrich
Campbell Barton
Joseph Eagar
Nathan Letwory
Brecht Van Lommel
Janne Karhu
Chris Want