Limit

The Effects->Limit command in the Motion module allows you to use a polygon mesh as a boundary for any other SOFTIMAGE 3D object. For example, it can be used to keep the points of a tablecloth on top of a table, making it easy to realistically drop a cloth over an object. The Restore options allow you to prevent the object from deforming unrealistically.

Note:

Since only the vertices (not the faces or edges) of the target object are limited, the limiting polygon mesh may poke through in places. To fix this, duplicate the limiting polygon mesh, push its control vertices out slightly, hide the original polygon mesh, and use the new polygon mesh as the limiting polygon mesh.

Procedure

The Limit effect requires three objects: a source object, a target object, and a limiting polygon mesh.

The target object should be a duplicate of the source object, perhaps moved or deformed. The Limit effect considers each point of the source object and checks if the line from that point to the corresponding point on the target object intersects the limiting polygon mesh. If it does, the point on the target object is moved to the point on the limiting polygon mesh where the intersection takes place.

If the Restore characteristics option is active, the target object is further deformed and limited according to parameters set in the dialogue box.

1. Choose the Effects->Limit command in the Motion module. The Limit dialogue box is displayed.
2. Set the parameters as desired.
3. Pick the source object, the target object, and the limiting polygon mesh.

Parameters

Restore Characteristics

When this option is selected, various parameters of the target object such as Surface area or Edge lengths remain at the source's values despite the deformation caused by Limit.

Limit Iterations

The number of times to relimit and restore. This value is only used if the Restore characteristics option is selected. A higher number of iterations takes longer to calculate, but creates more realistic results.

Restore Iterations

The number of iterations of the restore algorithm per limit iteration.

Source Object Animated

Lets you specify whether the source object is animated or not. If the source is animated, the restore values may change from frame to frame; this significantly increases calculation time. For this reason, you may not want to select this option.

Limiting Mesh Animated

Select this option if the limiting polygon mesh is animated.

Don't Tweak Tagged Points

Prevents the Restore characteristics option from moving tagged points, but they are still limited.

Importance Of Different Restorables

As a rule, higher numbers mean more important restorables. If Edge lengths is 50 and Face angles is 10, the effect prioritizes edge lengths 5:1 over face angles. If volume is the only restorable you need, use a value of 1 and give everything else a value near 0. For stable results, it is recommended that you always give priority to Edge Lengths.

Next, Previous, Delete, Key, and Frame

Next advances to the next keyframe, Previous goes back to the previous keyframe, Delete removes a keyframe, and Key sets a keyframe at the frame you specify in the Frame text box. These controls are available only after you have set the initial parameters in the dialogue box and clicked Ok. To return to the dialogue box and edit keyframes for the effect, select the effect icon and choose the Effects->Edit Parameters command in the Motion module.

Last updated 02-apr-1998