You can start the cloth simulation by clicking the Play button below the timeline. The animation is calculated from the first to last frame defined, then cached so that you can replay it quickly. You can start the simulation again by directly jumping to any frame.
To calculate the whole simulation quickly, go to the last frame of the simulation.
You can stop the simulation at any time by clicking Cancel on the progress bar.
If you want to save the simulation when you save the cloth scene, select the Save Simulation option in the ClothOp property editor. Softimage saves the simulation as much as is cached on disk so that this information is retrieved the next time you load the scene, thus saving you some time. The cache is optimized to store as little data as possible.
If you don't select Save Simulation when you save the scene, the simulation is recalculated the next time you load the scene.
You can also reuse and display an existing simulation to restart the simulation computation from the first non-computed frame. Any time a scene is reloaded, each of these simulation operators verifies if its old PTC file sequence still exists. To do that, the file sequence "magic number" is compared with the magic number saved with the operator. If the PTC sequence still exists, an automatic restart on the last valid frame is performed.
From that frame on, further recomputation (due to any change in parameters or obstacles) starts from the Restart Frame+1, while all frames between the Start Frame and Restart Frame are preserved.
You can specify a Restart file name(.ptc file) for the cloth simulation in the Cloth property editor. PTC files record the position and physical properties of the cloth object at each frame.
Each time you exit Softimage, delete a cloth object, or close the scene, you can erase all PTC files that were recorded and cached by selecting Clean cached files. If you don't select this option, the .ptc files are saved in the folder with the restart file name you specified.
From the Simulation page of the simulation operator's property editor, select Write Cache to save the simulation in .ptc (cloth) files that you specify with the Restart file name (one file per frame). These files record all the simulation data for each frame of the simulation.
Play the simulation to record the frames to the file. PTC files with the name you specified are saved for each frame of the simulation.
On the timeline, go to the frame at which you want to restart the simulation and select Restart from file. Select the .ptc file with the frame number that corresponds to the current frame you're at.
All the frames of simulation before this frame are read from the file which means that they don't have to be recalculated. Computation then starts from the current frame onward. When you restart, the simulation properties' values can be different from those used to generate the .ptc file.
Each time you exit Softimage, delete a simulation operator, or close the scene, you can erase all .ptc files that were recorded and cached. To do this, select Clean cached files.
If you don't select this option, the .ptc files are saved in the folder with the Restart file name you specified.
