Version 1.0 Alpha

April 28, 2001

Written Peter Watje

watjep@mindspring.com

This plugin is what I define as charityware and can be freely distributed. If you find it useful make what you feel as an appropriate donation to your favorite charity. You cannot charge or make any money from this routine by reselling or bundling them with another package/cd/web page without my permission.

To install this routine just copy the ObjectDeform.dlm file into your 3ds Max plugin directory.

This modifier lets you deform one object with another. Apply the Object Deform modifier to the object that you want to be deformed. Create another object and animate it cross the surface the object. The pick that object as your deform object. This will allow you to do effects like foot prints in the snow, or dragging your finger in the sand.

Deformer Object – this is the object that will be doing the deforming/

Standoff Dist – this is how far the surface will stay from the deforming object.

Quad Dept – This texture uses a lot of intersection with the mesh and uses a quad tree to make this fast. Setting this value lower causes it to be slower, but use less memory. Increases this value will make it faster but cause it to use more memory exponentially. Ideally the more polygons in your object the higher you should turn this up to prevent slow downs.

At 10 it will consume roughly 50+ megs of memory. Use this size only when you have gobs and gobs of memory and using mesh with lots and lots vertices.

At 9 it will use roughly 10+ megs.

<9 it will use around 3 megs or less.

The memory consumption is based on 1000 vertex sphere, so sizes will vary also based on the number of vertices and faces in the mesh.

ZDepth Collision – This is the first method of deforming the mesh. This is a relatively fast method, but requires that the collision object’s Z Axis be somewhat perpendicular to the surface for it to work well. Basically it transforms the surface into the space of the collision object. Then any point that is below a face in the Z Axis is moved above that face.

Inside/Outside Collision – This method uses an inside/out algorithm to deform the mesh. It is a quite a bit slower than the ZDepth method but allows you to not have to align the collision object to the surface. It also requires that the object be a closed object and works best with non concave surfaces. Basically if a point is inside the collision object, it is moved along its normal until it is outside the object. The Dents and Quality only affect this collision type.

Dent – If this is checked the points are moved along their negative normal.

Quality – This determines how accurate the collision is. The higher this number the more accurate collision will be but slower.

Falloff Effect – This will try to smooth the vertices surrounding the effect. This code is still pretty rough and not working that well. The value is how far out to smooth.

Remember Effect section is used when you want the effect to accumulate over time. Dragging you finger around is sand is an effect that you can get with this. Normally the effect is only present at one frame with this you can have the effect present across multiple frames. The only problem is that this is not an interactive effect, you have to re solve every time you want the effect to update.

Affect Multiple Frames – This turns this effect on and off basically turning on/off the cache.

Start Frame – This is the start frame

End Frame – This is the end frame

Solve – This will solve the effect and cache it to memory. You need to solve every time you want to change some aspect of the effect.

Clear Memory – This will clear the cache freeing memory but losing the effect. This effect can eat up a considerable amount on memory on larger meshes. If this is the case you can use the Point Cache modifier to cache the effect to disk and then clear the cache and turn the modifier off.

Quick Use Tutorial

1. In the top view create a plane 200x200 with 100 segments in both directions.

2. Create a 20x20x20 box centered on the plane.

3. Assign the Object Deform modifier to the plane.

4. Set the box as your deformer object. The vertices bounded by the box on the plane should jump so that they above the box.

5. Set the Standoff Dist to 4, and notice now that the vertices will displace 4 units above the box.

6. Now rotate the box 45 degrees along the local Y Axis. Notice that the vertices are transformed along the local Z Axis of the boxes. This is because the default method is ZDepth which moves the points along the local Z.

7. Now rotate the box another 90 degrees. Notice it now deforms the point into the plane since that is now the direction of the box’s local X Axis.

8. Now set the Collision Type to Inside/Outside. You will get a different looking deformation. The reason is that first it only affects points inside the box. Next it moves the points based their normals instead an axis. Turn on the Dents check box and now the deformation will go along the negative normals.

9. Adjust the Quality spinner down and notice as the quality goes down, the farther away from the mesh the points become. This spinner controls how many iterations the algorithm will use. The more iterations the closer the points will be to the surface.

10. Now animate the box around the surface of the plane. Notice the effect is not accumulative.

11. Now go to the Remember Effect section and turn on Affect multiple frames, scrub the timer and notice that nothing has changed. This is because this mode is not interactive. Leave the start and end frames at 0 and 100 and press the Solve button.

12. Now the effect will accumulate. Just below the Solve button it tells you that the cache has consumed 1.42 megs of memory. The more frames you solve or the larger the mesh the more memory you will consume. You can use the Point Cache modifier to diminish the amount of memory used.

13. Note now the effect is not interactive, if you move the box and want the effect to update you must hit the solve button.

Known Bugs

The Falloff is still a pretty crude algorithm

It only works with tri mesh objects

Since it samples only on frames fast moving objects will create a noncontinuous effect.

If you have any question you contact me at:

mailto:watjep@mindspring.com