Improvements to the Cloth Simulator

Here we take a look at the most significant developments in the cloth simulator from the past few months. This work was based on the proposal found here. The code developed during this time is at the moment still in its own branch, but will be merged at some point during the 2.8 series.

Mass Spring Model

With the old mass-spring model used by Blender, the user could have no independent control over bending and compression, or stretching and shearing. As shown in the image below, the tension and shearing springs were coupled together.

Tension and shear springs shown in blue, and compression/bending springs shown in red. (springs of same color translate to a single property in the UI)

Also, a single linear spring was responsible for both bending and compression resistance, as can be observed in the animation below. Furthermore, the usage of linear springs for resisting bending, deviates significantly from actual cloth behavior, and even allows bends to be flipped to the opposite direction without any resistance.

(Cross-sectional view) This video shows that the same spring was responsible for providing both compression and bending resistance, by pushing opposite sides of a bend away from each other.

The new model has componentized springs, and the addition of angular bending springs. Combining these things, the user has complete control over every aspect of the cloth stiffness independently.

Tension springs shown in blue, compression springs shown in red, shear springs shown in cyan, and angular bending springs shown in green. (springs of same color translate to a single property in the UI)

Beyond that, the angular springs behave much more realistically, and are signed, meaning that the cloth is aware of the direction of the bend, thus not allowing it to get flipped.

(Cross-sectional view) Here in the new model it can be seen that a new dedicated angular spring was added specifically for bending, while the compression springs always stay flush with the cloth surface.

Below are comparisons of various aspects of the cloth model that were improved.

Comparison of the old cloth bending model (left) and the new model (right).

Comparison of the old combined isotropic cloth tension model (left) and the new componentized anisotropic stretch/shear model (right).


Plasticity is the most significant property of deformable materials that was missing from Blender’s cloth simulator. Plasticity is the property in which materials retain deformations after being subjected to stresses, and thus don’t return completely to their original shape. In addition to the improved mass-spring model, the inclusion of this property, is the final piece in enabling the simulation of virtually any known deformable sheet material.

The same simulation shown without plasticity (left), and with plasticity (right).

External Rest Shape

The “Dynamic Besemesh” feature allows the underlying cloth mesh animation to be used as the new rest shape on each frame, thus enabling effects where the cloth changes shape throughout the simulation. However, an issue arises when this feature is used in combination with pinning. Because the pins also utilize the underlying mesh state to determine vertex locations, one could not have independent control over the pin locations and the dynamic rest shape. Now support has been added for using another mesh (with identical topology) as the rest shape.

The video below demonstrates the described issue, and shows how one can now animate rest shape and pin locations independently.

From left to right: (Top row) Animated cloth mesh (before simulation); Simulated cloth using own mesh both for pinning and as dynamic rest shape; (Bottom row) Animated mesh used as rest shape; Simulated cloth using external rest shape mesh;

  1. Hey guys, congrats for the nice work. Do you have plans tu fully integrate this simulation with Physics?

  2. Hello, I was wondering if it is planned that in the future version of blender about improvements regarding cloth simulations, for example to integrate tools to grab the cloth in the same way as what is already the case on marvelous designer for example.

  3. PS why not call these by there regular names, like in the article, stretching and shearing? Why is compression used?

  4. Hi. Is the new cloth already in the current 2.8 alpha version?

    Best wishes

  5. Fantatic!

  6. guruuz.. it’s amazing… really now I felt that previously that was fake.. and now it’s good.. maybe in next update you guys make us feel.. this new update is fake and the next coming would be more realistic.. :D

  7. In the middle of project at moment, where I use cloth to simulate what can be loosely called a soft body (puffball mushrooms deflating). The possibilities with old cloth are quite limited, but I’m glad they’re there at all. The main obstacle I’m encountering is the way cloth reacts to it’s topology, especially regarding forces.
    Given that polygonal density affects creasing of the cloth, it has to be at least somewhat even. Which in turn means that any non-flat geometry, especially a sphere, has to have topological poles (intersections of more or less than 4 edges). Now, when a force field pushes the cloth, from what it looks like, the force depends on surface area of the polygon and some areas being of denser topology result in higher spring to force ratio resist to the force stronger. In a situation where there are large initially flat surfaces this difference produces distinct creases along the edges of changing topology as well as notable motion pinning on denser areas.

    TLDR – could the cloth please have an option to ignore polygon surface area and/or normals when calculating reaction to force fields?

  8. I can’t wait for this. This looks totally amazing!

  9. Interesting. I hope 2.8 Official comes out soon.

  10. So the new features are implemented to the newest version of Blender 2.8 or not ?

  11. i tried the last version 2.8 and i don’t like the new changes and the cloth modifier didn’t work

  12. This is great, but I’d really like to see you all tackle the de-intersecting / collision-pinching methods that Pixar described in their 2003 SIGGRAPH paper “Untangling Cloth”. (I put the link in my comment’s website link) Because all the realistic crumpling in the world won’t help you if the simulator can’t handle normal collider-(self-)intersections through the cloth surface that typically happen during animation.

  13. Very impressive!

  14. Hey, those are fantastic news! But I need to ask the same question as Michael – is there a build available with it already or do we have to wait longer?

  15. Is there a working build for this?

  16. Is there a working build for this?

  17. gpu acceleration please!…seriously though between new viewport GI, the amazing manipulators and now this….christmass seems to be early this year, as well as next year….now if we could get some game engine love my world would be perfect.

  18. Quite nice! I can’t wait to see how this works on a character model! I’m quite curious to know if there’ll be any updates to collision detection!

    • Thanks! This was used for all the henchmen and the doctor in Agent 327.
      A demo of all the cloth from the film is coming soon!
      As for collisions, improvements were made in regards to performance and reliability, but work is still in progress.

      • Hey Luca.. a tutorial on how to sew clothes together to make clothes in blender would be cool.. like how you do in Marvelous Designer

  19. If you are looking for code for cloth tearing effect, check this sample out from javascript.

    Hope this can be used in python.

  20. Nice Improvements!
    But I’d like to see a function for tearing cloth.

  21. Multithreaded? The shorter the wait the better the outcome.

    • This. Is it multithreaded or even GPU accelerated?

    • Well, collisions have been multithreaded. And other general performance improvements have been made.

  22. Please add a function to tear cloth!

  23. This is nice. But I’d really like to see this working on an animated character with multiple layers of clothing made of different materials, with belts, straps, stitching, quilting, etc.

  24. Long missed improvements. Even a flag, which is a classic, basic tutorial, which there are tons of, becomes a headache when done for production, as the final result is “the most successful simulation” instead of cloth of particular characteristics, not to mention cases requiring plasticity.
    Any improvement is great, and this looks like a major one.

    Just in case, and if it’s not not yet carved in stone – please don’t forget that target shapes/pinning often are to be animated. Inability to do things like that is a widespread showstopper for many things simulation related in Blender.

    • This has been implemented. You can now animate target shapes, and pins independently (as shown in the last clip). You can also animate the influence of different pins throughout the simulation.

  25. omg, those improvements are unreal. Easy to see why so few wanted to use the old cloth system. Can´t wait to see your plans for Blender particles :)

  26. This is amazing!

  27. OMG that looks almost real!

  28. isotropic cloth tensión looks really amazing. How it looks combined with twisting?

  29. Amazing!

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