What’s the most important thing when creating computer animated films? First it’s the story. Then it’s the realism of the graphics. Light, materials and the way they react with the environment to create a realistic feel. Cloth simulations are one of the hardest and most important pain points to solve in terms of bringing cloth physics to life in computer animated films.
What’s marvelous designer? For those who don’t know, it’s a 3d software that specializes in clothing design. It uses its own proprietary scripting language which allows you to control all aspects of simulation from basic geometry manipulation all the way up to advanced mesh deformation including tension, stretching, folding, layering among other things. The best part about this whole system is that you got an instant visual feedback on how your simulation will look with your character animation.
The most difficult thing about cloth simulation is the massive file size and the overall organization of the various files to make up the scene, character, animations, clothing, and materials. Marvelous designer is nice because you can start with your character animations from iclone. Export those animations out to an fbx file with motion. Bringing that animation into marvelous designer allows you to simulate the clothing on your character so it reacts to your characters movements, gravity, and even wind, if introduced.
It’s all fun up until this point. Once the cloth is animated, this is where the real problems start to come into play.
You can only export a very small amount of clothing data from marvelous designer out to a format that’s usable in unreal just due to mere file size. For example, one outfit can take up around 6gb for a short 700 frame animation. This adds up quickly.
The other issue is getting this simulated cloth into Unreal and on your character. This is where I am starting to work through my workflow. So lets break this down into some steps.
- Create character
- Design character clothing
- Ensure all the us and material for all the clothing is in one image
- Adapt clothing to standard a pose
- Animate character in iclone including that a pose at the start of your sequence
- Export the nude animated character out of iClone to Unreal preset at 60 fps
- Import animated character as avatar into marvelous designer at 60 fps
- Simulate the clothing
- Export the clothing as an Alembic file at 30 fps
- Export segments of the animation and name according to frames
- Import the alembic into Unreal and apply to the scene over your character
You want to make sure that this is the last step in your animation process. Once you have the animation, re-animating the cloth is time consuming so ideally you only want to do this once.
In theory this all works. Let’s take a look at the process from beginning to final animation.
The video above is a general beginning of the cloth physics simulation process. One thing to note, however, is that it’s important for you to not only simulate your character’s clothing but ensure that your story you are creating is compelling enough to spend the extra time to animate the cloth to begin with.