To increase the speed of the playback, mute any viewport that you’re not using by middle-clicking its letter identifier (A, B, C, or D). You can also hide the default grid in any viewport (press G).
Playing Particle-based Simulations
Although playing back a particle-based simulation is very simple, there are a number of issues related to it. Each of the particle-based simulators has special modes of playback, you can cache the simulation in PTP files to make playback go faster (after the files are cached), and you can also use a special player to play these PTP files.
At the first frame of a simulation, no particles are emitted. One frame later, particles are emitted but not updated. One frame after that, the previously emitted particles are updated and new ones are emitted, and so on for the rest of the simulation.
This is done so that an animated particle emitter object is at the same frame as the particles it’s emitting. If particles were updated at the same frame they were emitted, the particles would be one frame ahead of the emitter.
To play and cancel a simulation
• Click the Play icon in the playback panel below the timeline or move the playback cursor in the timeline. You can see the simulation’s calculation on the progress bar that appears.
What you see depends on which Execution State Mode you’ve chosen for playback (see Choosing the Way Particle Simulations Are Played Back for particles and Choosing How the Explosion is Played for explosions—fluid doesn’t have a choice of execution modes).
• Click the Cancel button on the progress bar or press Esc to stop the simulation at any time.
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To increase the speed of the playback, mute any viewport that you’re not using by middle-clicking its letter identifier (A, B, C, or D). You can also hide the default grid in any viewport (press G). |
Caching the Simulation in PTP Files
When you play a fluid simulation for the first time, the explosion simulation with Interactive mode, or a particle simulation in Standard Caching mode, the result is cached in files with the extension .ptp. These PTP files record the position and physical properties of each particle in the stream. The file sequence is written back each time you modify any parameter affecting the simulation. Caching the simulation to file means you can move to any frame and get an update, as well as play the simulation backward.
One PTP file is created for each frame of the simulation. By default particle simulations use the name Particles plus a number counter (such as Particles1.ptp); fluid simulations use the name Fluid followed by a number; and explosions use the name Explosion followed by a number.
Changing the Default PTP Storage Folder
The first time you cache files for a particle-based simulation, the PTP files are saved in your temp folder, usually on C:\, depending on your system’s environment variable. The best solution is to choose an output folder and file name for each particle simulation you create, such as your current project’s Simulation folder.
Once you’ve done this, the PTP files for all subsequent particle simulations you create will be saved to this folder because the path is saved with your Softimage user profile.
To specify the storage folder for PTP files
1. Open the ParticlesOp, FluidOp, or ExplosionOp property editors.
2. On the Output page in any of these editors, specify an Output Sequence folder and file name for the simulation.
- If Usr is on, the path is displayed as you entered it.
- If Res is on, the resolved path is displayed.
If you reuse the same file name, that simulation updates the existing PTP sequence.
To prevent overwriting the default-named simulations, give each simulation a unique and descriptive name for its PTP files.
Every time you delete a particle-based simulation, close a scene, or exit Softimage, you can automatically delete its PTP files. To do this, select the Clean Cached Files option on the Output page of the simulator’s property editor, as shown above.
If you keep the PTP files, Softimage doesn’t have to recalculate the entire sequence, so the next time you view a frame, it plays back much more quickly. As well, having PTP files allows you to play a simulation backwards and scrub back and forth on the timeline.
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If you decide to keep the PTP files, make sure to check the storage folder you have defined for them and delete any unused files. These can build up quickly and take up lots of space if you don’t occasionally do some housecleaning! |
If there is not enough free space on your disk to calculate the PTP files, the particles won’t be shown and an error is triggered.
Playing PTP Files in the Particle Player
If you have cached PTP files, you can play them back in the particle player. You specify the PTP files you want to play back, and the particle player creates a particle cloud with a simulation operator that reads the PTP files and simulates them. The PTP files are played back in real time, which is an optimum way of previewing them.
The simulation operator uses the basic simulation and emission properties and plays that information. To use the correct particle type information (color, sprite, etc.) for playing back for the simulation, you need to have the particle types that are used by that simulation in your current scene/project (particle types are saved at the project level).
Because you don’t need the whole particle system to be on your machine to view the PTP files, the player is very useful for sharing a particle effect library between multiple users.
To play back PTP files in the particle player
1. Choose Create > Particles > From File from the Simulate toolbar.
2. In the Load Cache File dialog box that opens, select any PTP file from a sequence that you want to play.
3. In the Particle Player property editor, set the Start Frame and number of frames (Duration) over which you want the sequence to be played.
4. For the Input Sequence, specify the first PTP file in the simulation sequence that you want to play back. The subsequent PTP files in that sequence are then played.
5. If you want to save the input sequence PTP files under a new name, select Write Output Sequence and specify a location and name for the Output Sequence PTP files.
Autodesk Softimage v.7.5