Shock3D

The Channel->Shock3D command in the Motion module allows you to simulate real-time dynamic collision between models. Shock3D supports the collision between the bounding sphere and/or bounding box of single objects in 3D space using both the Custom and Channel menu cell commands to exchange data with SOFTIMAGE 3D.

Procedure

1. Create or load the models you want to use.
   
   A single hierarchy must be provided for Shock3D to start the simulation. The rules to follow for creating the model are:

• Place all the objects with the same set of properties in a single sub-hierarchy with a null parent and assign the set to it so that all the children receive the same properties. Only the bounding sphere of each object is considered during the simulation. Object types considered correctly are polygon meshes and patches. The null parents of the spheres must not be translated nor rotated from the global centre of coordinates.
• The hierarchy cannot exceed three levels. The hierarchy of the selected model is not taken into consideration during the simulation. Each object moves separately. The hierarchy is used only for an easy association of object properties.

2. Choose the Channel->Shock3D command. The Shock3D dialogue box is displayed:
3. Enter the name of the moving objects and their properties. Select the simulation parameters.
4. Click Ok.
5. Select the model root.
   
   The system calculates the resulting simulation data to a file (usually
   /usr/tmp/Shock.data).
   
   
6. Select the Channel->Get Channel Setup command in the Motion module.
   
   In the specified database, select the file called rebels_setup. This file contains all the information that the channel driver needs to read the information back from the data file.
   
   Note:
   
   Next time you run the Shock3D effect, make sure to delete this file before starting. This ensures that you will avoid any problems overwriting it.
   
   
7. Be sure that the time line is placed at the frame you selected as the starting frame for your simulation. Also, make sure that your model hierarchy is selected.
8. Choose Channel->Channel Run->Sequence I/O in the Motion module. The data coming from the data file is applied to your models.
9. Play back the animation to view the results.

If you want edit any parameters, choose Channel->Shock3D again and repeat steps 4, 5, 7, and 8. You don't need to recall the channel setup since you didn't change the model used.

Parameters

Start Frame

Start frame for the simulation: the default is 1.

End Frame

End frame for the simulation: default is 100.

Frame Rate

Frame rate set in SOFTIMAGE 3D: default is 25.0.

Precision

Simulation precision level. It describes the sampling rate per frame. A higher value results in a more accurate simulation, but it takes longer to calculate. The values range from 1 to infinity: the default value is 10.

Gravity

The gravity along the y-axis. Default is 0, with earth value being 9.8.

From Frame

Frame from which the gravity works.

Bound X

X-dimension of the simulation field in the plane, or floor. The field is always centred according to the world. The default is 50.0.

Bound Y

Y-dimension of the simulation field in the plane, or floor. The field is always centred according to the world. The default is 50.0.

Bound Z

Z-dimension of the simulation field in the plane, or floor. The field is always centred according to the world. The default is 50.0.

Air Density

Density of the simulation atmosphere. The default is 0.0.

Wall Roughness

The amount of wall friction. A value of 0.0 means that the floor doesn't affect the object's simulation. Range is 0 to 1, with the default being 0.0.

Random

This global value describes the "surface quality" of the floor. A value of 0.0 means that the floor surface is perfectly "clean." A value of 0.1 produces a fuzzy random movement of the objects. Suggested values are close to zero (the default).

Data File Path

Path and name of the file where the simulation data is placed. The default is /usr/tmp/Shock.data. If you change this path, you must also change the path in the DataFileDrive.drv file.

Current Database

The SOFTIMAGE 3D database where Shock3D stores the channel setup for your simulation. You must have the environment variable SI_DBDIR set in your account and you must specify a valid database name as found in the DatabaseDir.rsrc file. The default database is TEST.

Continuous Collision

Shock3D can't usually manage continuous collisions, so you may see an object sinking into another object (but never into the plane, or floor). To avoid this, you can try to raise the precision or select this option which slows down the calculation. The default is deselected.

Verbose

Prints simulation statistics in a shell, as well as the percentage of simulation completed. The default is selected.

Node Name

Name of the object or the parent of models with the same physical properties.

Linear Speed

Linear speed of the node object along the global axis. Default is 0.

Angular Speed

Angular speed of the node object around the global axis. Default is 0.

Density

Defines the object density and mass. Values range from 0 to infinity. The default is 1 (water density).

Elasticity

Defines the object's elasticity. The higher the value, the more the object bounces against the others. Values range from 0 to infinity. The default is 1, where no energy is lost after a collision.

Roughness

Defines the object's friction. Values range from 0 to 1, with the default as 0.

Fixed

The object does not change the starting velocities; if it is still, it becomes a fixed obstacle for moving objects.

Bounding Box

The bounding box of the object is used during the simulation; otherwise, the bounding sphere is used.

 

Shock3D Channel Driver

The Shock3D custom effect comes with its own channel driver. This driver allows SOFTIMAGE 3D to read the animation from the data file created by the effect. The installation program automatically installs two files (DataFileDriver and DataFileDriver.drv) in the specified directory (usually the one pointed to by the SI_CHNL_DRIVER environment variable).

Note:

If you change the Simulation Data File you must also change it in the DataFileDriver.drv file in your channel directory.

This driver can also be used with other applications that can produce ASCII data in the DataFileDriver format. The format is:

3        
0.1 0.0000 0.0000 1.0000 33.1245 -1.8211 321.1224 
0.1 9.3221 0.0000 7.1000 33.1245 -1.8211 -65.3244 
0.1 0.0030 0.0060 1.0800 33.1245 -1.8211 11.1243 
0.2 0.0210 0.0000 1.0000 33.1245 -1.8211 63.1224 
0.2 0.0123 0.0000 1.0000 33.1245 -1.8211 -0.1524 
0.2 0.0121 0.0000 1.0000 33.1245 -1.8211 21.2124 
...

where:

• the first number is the number of objects animated per frame
• one row for each object is at each frame with 7 float fields where
  • field 1 is the time in seconds
  • fields 2, 3, 4 are the translation values
  • fields 5, 6, 7 are the rotation values

Last updated 03-apr-1998