Collision Model & Physics

Posted Feb 12, 2012
Last Updated Mar 15, 2017
Smooth all elements of the collision hulls to make the valid for a concave hull. Pick a node in the scene to smooth for converting to a concave hull. Unhide all the Hull nodes for this model. Hide all the hull nodes for this model. Select in the viewport all of the hull nodes for this model. Enter Animated Friction (Five floats separated with a space). Generate $jointconstrain entries in the QC based on the bone IK limits. Use the reference mesh as the collision hull. Set this model to ignore itself when calculating collisions. Manually set the Rotational Damping of this model. Overrides must be On to use. Manually set the drag of this model. Overrides must be On to use. Manually set the damping of this model. Overrides must be On to use. Manually set the Inertia of this model. Overrides must be On to use. Manually set the mass of this model. Overrides must be On to use. Click to see how many hulls are in this model. If $concave is off, it will always be 1. Turn on the Overrides to manually set Mass, Inertia, Deamping, Drag and Rotational Damping. Set this model as Concave. Required if your collision model has multiple pieces. Calculate Mass automatically from volume and surface properties. Create/Select the Mass Center helper. Choose main content of this model. Launch the Hull Helper UI. Remove currently selected objects from Hull. Make one hull per Element Sub-Object per Object in Hulls. Maximum vertices in each Hull Element when using Quick Hull. Add Selected Nodes to collision model. Pick a mesh to add to the collision model. Pick Collision Model Node. Collision Model Rollout in WWMT.

The collision model is a convex geometry that defines the physical boundaries of the model. Generally speaking, this model should be a low-poly copy of your model broken up into convex pieces. If possible, use a single convex shape for the model! If there are more than one pieces to your collision model (either separate scene objects or meshes with multiple Element sub-objects), remember that you will have to later set the $concave flag.

Learn more about Generating a Collision Hull.

Note that there is an option in the WWMT Settings (as of Version 1.0) called Processed Hulls become Non-Renderable that you can turn on/off. When set, all hulls added to a model (or meshes processed by the collision hull tools) are made non-renderable. This, however, should be turned off if you have also turned on the new Export Non-Renderable Mesh as Bone.

Pick Collision Model

Click this button so that you can then select the root Collision Model (also called a Collision Mesh or Collision Hull). The Collision Mesh should be a convex piece of geometry that has a unique smoothing group applied to each convex piece.

  • Even though the Collision Model does not ever display in-game, it still needs to have a material. (The Process CM button does this for you.)
  • If you need a $concave hull, click the Process CM button after all hulls are added to the model.
Append CM

Click this button so that you can select a single mesh to add to your Collision Model. This will add a mesh to your Collision Model. If you need to add multiple objects, see Add CM Sel below.

Add CM Sel

Pressing this button will automatically add all selected objects to the Collision Model. Please see the hints above for Append CM.

Delete (CM) Sel

Pressing this button will automatically remove all selected objects from the Collision Model. Please see the hints above for Append CM.

Quick Hull

This button will generate a convex hull for each Element sub-object of each mesh in your hull. It utilizes the nVidia PhysX plugin for 3ds Max (now bundled in 3ds Max 2012+ as MassFX).

  • This button is inactive until you have selected a model with the Pick Model Button(and even then inactive until the feature has been included).
  • You can only use the hull generation built into WWMT using MassFX (Max 2012+).
Launch Hull Helper

Launches the Hull Helper Floater.

Collision Model & Physics Settings

Concave | $concave

Tells the compiler that the Collision Mesh should be broken up into the individual objects and their Element sub-objects. If not set, the collision mesh objects are converted to a single convex mesh.

  • Remember that every mesh in the collision hull must have a smoothing group applied to it.
  • If an object in a collision mesh has multiple Element subobjects, each Element must have a unique smoothing group.
Contents | $contents

This menu lets you choose the content_type of the model. The default is solid.

Mass Center | $masscenter

Click this icon to create a $masscenter point helper (or select the model's $masscenter helper if one was already made). This will create the center of mass for your model. By default, the model's center of mass is at its origin--this will let you move that to an appropriate spot.

Auto Mass | $automass

Click this setting if you want the mass of the model to be determined automatically based on the model's $surfaceprop.

  • Clicking this option will override any value entered in the Mass spinner.
Auto Hull

Check this option if you want studiomdl.exe to create a collision hull from the base model mesh. Using this option means that you do not have to create a collision mesh.

  • You should not use this for animated models.
  • When using this option, you probably also want to turn on $staticprop.
  • If your model has multiple meshes or Element sub-objects, and you want the collision hull to "shrink wrap" to these, you will need to click the $concave option.

Turn this on to manually set the Physical Properties of this model (like the mass, inertia, etc). When on, activates the override spinners for those properties.

Mass | $mass

Manually set the mass of the model in Kilograms.

Inertia | $inertia

Manually set the inertial scale.

Damping | $damping

Manually set the damping scale.

Drag | $drag

Manually set the drag scale.

Hull Utilities

Select Collision Hulls

Click this button to select all objects in the scene that are part of your collision hull.

Hide Collision Hulls (Hide CM)

Hides all meshes that are part of the collision hull.

Show Collision Hulls (Show CM)

Shows (unhides) all meshes that are part of the collision hull.

Prepare Collision Model (Prepare CM)

Click this button to select a mesh to prepare for becoming a Collision Hull. When you've clicked this button, then select a mesh in the scene. Be aware it only works on one mesh at a time. Here is what it does:

  1. The item is converted to an editable poly
  2. Each Element sub-object is given a unique smoothing group
  3. A texture is applied to the object
  4. Object is set to non-renderable
Process Collision Model (Process CM)

Click this button to automate the Prepare CM function (see above) on each mesh in the Collision Hull.

  • This function differs from the Prepare CM in that meshes are not converted to Editable Poly. When using this function, objects that are not an editable poly are given a Smooth modifier. Note that if you use this function multiple times, the tool will keep adding new Smooth modifiers.

Collision Model Rollout in WWMT.

UI for the collision model rollout.

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