Storing a Morph Target
Storing a Morph Target will allow you to store the current surface area so that it will be maintained during the simulation.
For example, load the Sim_HeadCover.zpr project from LightBox, which already has a morph target stored.
- Select the SubTool you would like to have the simulation run on.
- Turn on visibility for all SubTools on that the surface needs to collide with. Hide any that you wish to be ignored.
- Make sure Dynamics >> Gravity is on.
- Press Dynamics >> CollisionVolume to calculate the volume of all visible SubTools, or Dynamics >> Recalc if already active and the scene has changed.
- Press Dynamics >> Run Simulation.
- You can stop at any time by clicking anywhere in the ZBrush document or pressing the Spacebar.
The Smooth brush will by default contract the mesh but leave the edges unaffected. However, you can instead use the SmoothCloth brush to allow all points of the surface to be smoothed.
Note: The SmoothCloth brush allows this behaviour thanks to a specific modifier. To change this, hold Shift to get the Smooth brush settings, and change the Brush >> Smooth Brush Modifiers >> Min Connected slider to 1. This allows any point of the mesh to be smoothed.
Low Resolution Meshes are key
Remember to use a low-resolution mesh for cloth. Don’t expect the simulation to work on a mesh with five million polygons.
The idea is to create a low-resolution mesh, apply the effects and then subdivide once you are satisfied with the cloth shape.
While keeping to as low a polygon count as possible, you will also find that denser meshes with smaller polygons result in smaller folds. This can be useful when creating a particular type of cloth.
To be able to work with cloth simulation while still seeing the smoothness of a higher resolution model, use Dynamic Subdivision. In fact, this will even let you start with a planar piece of geometry and use the Tool >> Geometry >> Dynamic Subdiv >> Thickness slider to dynamically add depth to your flat geometry. This feature will even work with the Dynamics >> Self Collision slider.
The Dynamics >> Max Simulation Points slider controls the higher number of points upon which a cloth simulation can run. Any mesh with a higher polygon count than what the slider is set to will automatically disable the dynamics. You can set higher values but the simulation will take a lot longer to run because it has to account for so many more points
To run without interacting with the floor, turn off Dynamics >> Floor Collision. Floor height can be adjusted using the Draw >> Elv slider. A value of -1 will automatically make the floor grid snap to the lowest SubTool.
Deformation Animation Recording
Turning on the Tool >> Layers >> Record Deformation Animation will record the mesh changes that occur during the simulation. This will work with either the Run Simulation or the cloth brushes. Only changes to your mesh are recorded, so you can stop/start the simulation and change the camera angle without it affecting the result. When you have finished, turn the button off and you will be asked to save the recording as an MDD file. This can be loaded back into ZBrush using the Tool >> Layers >> Import MDD button and rendered using BPR and the TimeLine, or you can use another application that supports MDD files.