Mainly updated the Mantaflow version. It includes the new viscosity solver plugin based on the method from 'Accurate Viscous Free Surfaces for Buckling, Coiling, and Rotating Liquids' (Batty & Bridson).
In the UI, this update adds a new 'Viscosity' section to the fluid modifier UI (liquid domains only). For now, there is a single 'strength' value to control the viscosity of liquids.
This update introduces two improvements from the Mantaflow repository:
(1) Improved particle sampling:
- Liquid and secondary particles are sampled more predictably. With all parameters being equal, baked particles will be computed at the exact same position during every bake.
- Before, this was not guaranteed.
(2) Sparse grid caching:
- While saving grid data to disk, grids will from now on be saved in a sparse structure whenever possible (e.g. density, flame but not levelsets).
- With the sparse optimization grid cells with a value under the 'Empty Space' value (already present in domain settings) will not be cached.
- The main benefits of this optimization are: Smaller cache sizes and faster playback of simulation data in the viewport.
- This optimization works 'out-of-the-box'. There is no option in the UI to enable it.
- For now, only smoke simulation grids will take advantage of this optimization.
Scaling of forces needs more work. Before making changes to them it would be nice to have a setup, that works physically correct across multiple modifiers (cloth, rigid bodies, fluid).
This will be a to do for 2.92.
Use bool return type where possible instead of int (the return values from fluid object are already boolean instead of int).
Also removed several if guards in API functions. If one of the arguments is in fact invalid / nullptr (should not happen though), it better to catch them directly where they failed and not silently escape them.
This commit corrects the maximum resolution field in Fluid objects. The field should be set to the maximum possible resolution, i.e. it should not adjust with adaptive domains and stay constant all the time.
The reason for this is that this resolution value will be used to scale gravity. And this gravity should be constant for adaptive domains too.
It remains to be shown if this issue was the only reason for line-artifacts as seen in T74559.
This commit corrects the maximum resolution field in Fluid objects. The field should be set to the maximum possible resolution, i.e. it should not adjust with adaptive domains and stay constant all the time.
The reason for this is that this resolution value will be used to scale gravity. And this gravity should be constant for adaptive domains too.
It remains to be shown if this issue was the only reason for line-artifacts as seen in T74559.
Basic support for velocity updates with the APIC method.
This commit adds APIC to the already existing dropdown menu for the simulation method. The APIC plugin within Mantaflow has been updated to the latest version.
Being able to adjust the distance between fluid and obstacles comes in handy when trying to achieve a fluid motion over inclined obstacles.
Depending on the slope of such obstacles, already small adjustments of this value can help when particles stick to obstacle surfaces (i.e. make particles not stick to obstacles).
A general refactor / fix commit that should clear out the issues that have been reported on external forces and moving effectors (e.g. T79537, T81660, T80088).
The flood-fill helper serves as a sanity check for scenes with complex obstacles. Similarly to the holes filler function it ensures that there are no holes in obstacles.
In addition, it ensures that there will be no holes resulting from multiple intersecting obstacles.
In general, this commit should improve stability.
The OpenVDB update added a load() function. This function clashes with a helper IO function (only used when exporting and running the simulation externally) that was also named load().
Removed invel MAC grid since it is sufficient to use the cell centered vec3 representation. When setting initial velocities these will be interpolated by the setter functions.
All the changes made in the branch `soc-2020-fluid-tools` are included in this patch.
**Major changes:**
=== Viewport Display ===
- //Raw voxel display// or //closest (nearest-neighbor)// interpolation for displaying the underlying voxel data of the simulation grids more clearly.
- An option to display //gridlines// when the slicing method is //single//.
==== Grid Display ====
- Visualization for flags, pressure and level-set representation grids with a fixed color coding based on Manta GUI.
==== Vector Display ====
- //**M**arker **A**nd **C**ell// grid visualization options for vector grids like velocity or external forces.
- Made vector display options available for external forces.
==== Coloring options for //gridlines// ====
- Range highlighting and cell filtering options for displaying the simulation grid data more precisely.
- Color gridlines with flags.
- Also, made slicing and interpolation options available for Volume Object.
Reviewed By: JacquesLucke, sebbas
Differential Revision: https://developer.blender.org/D8705
Before: If the current frame is out of the cache start/end range, the viewport will show the fluid as it was on the last frame that was still in the cache frame range.
Now: If the current frame is out of the cache start/end range, the viewport will show no fluid at all (even if there are cache files present for this frame).
This fix is related / in response to T79423.
Instead of clearing forces at the end of the simulation step, they will now be cleared before writing to them, i.e. at the beginning of a step.
Also cleaned up minor areas that I looked at while making this change.
A collection of multiple changes that had been living in my stash:
- Use nullptr instead of NULL in C++ files
- Removed unused/deprecated functions from headers
- Cleared animatable flag in cache UI
- Comment cleanups
Use static_cast() where possible and refresh pointers for every frame when in replay mode. The latter is particularly important as this seems to have caused the issue where smoke in the viewport was flickering when loading data from pointers after loading them from disk for the frame before (e.g. when resuming a bake job).
New option that lets users the define the maximum number of fluid particles that will be allowed in the simulation. This can come in handy, for example, to ensure that the particle count will not exceed the hardware capabilities, or to avoid excessive amounts of particles in a scene.
New option that lets users the define the maximum number of fluid particles that will be allowed in the simulation. This can come in handy, for example, to ensure that the particle count will not exceed the hardware capabilities, or to avoid excessive amounts of particles in a scene.
This refactor is in response to reports in which the adaptive domain with noise caused a crash (e.g. T79009). It should also fix issues where the smoke appeared to be cut off when using the adaptive domain together with noise. It is also possible that some of these changes improve the lines issue from T74559.
These flags need to be set correctly in order to distinguish between data that comes from cache files and raw data that comes directly from pointers to the data in Mantaflow.
The issue is duplicated code. There are two functions that zero-fill
the frame number. They worked the same for positive frames numbers, but
behaved differently for negative ones.
On frame `-100`, `BLI_path_frame` outputs `-0100` and
`fluid_cache_get_framenr_formatted_$ID$` outputted `-100`.
I changed the behavior of the latter, because we depend on the behavior
of the former for much longer already.
Reviewers: sebbas
Differential Revision: https://developer.blender.org/D8107
Changed variable names from mmd, mds, mfs, and mes to fmd, fds, ffs, and fes. The author of this commits lights a candle for all the merge conflicts this will cause.
Always initialize the particle velocity of newly sampled particles to 0 if there are no initial velocities. Clearing the grid source makes sure that new particles will get a 0 velocity - and not interpolated from the associated grid.
This commit makes uses of the new OpenVDB IO in Mantaflow (introduced in 781f783a66ac).
From now on, fluid cache files in OpenVDB format will contain a list of grids per frame (before: one .vdb file per grid per frame). Besides regular grids, particle systems are also stored using OpenVDBs PointGrid data structures.
All older cache formats will remain fully functional:
- Uni caches (.uni) files are still available from the UI and can be used as before
- Raw caches (.raw) are no longer available from the UI, but loading them is still possible
- Old OpenVDB caches (one .vdb per grid) can no longer be baked either, but loading them is still possible.
It is also no longer possible to choose file formats for 'Noise' and 'Particles'. Instead there are now options to set the file format for 'Volumetric' and for 'Mesh' data.
Known issues (planned to be resolved soon):
- OpenVDB files are currently not taking into consideration the clipping value (FluidDomainSettings). Empty cells are therefore being written too. Depending on the scene, this can make file sizes unnecessarily large.
- Domains are not being exported at their world position. Instead they are always clipped to the origin.
This seems to be an error in rBb91b90f0dd3c9bff3b1a6e563c2cce293722ed16.
I found it, because I could not open the file in T77263 anymore.
Reviewers: sebbas
Differential Revision: https://developer.blender.org/D8065