$collisionmodel

$collisionmodel is a QC command available in all Source games.

It is used to embed a static collision mesh in a model for use in VPhysics calculations. Animated models (including ones that will become ragdolls) should use $collisionjoints instead.

Warning:Collision meshes should have extremely few polygons. See Collision mesh for examples.

Warning:Older engines automatically optimize meshes that are too dense, merging vertices that are close together. But this also ruins small collisionmodels, as it merges various vertices together that should not be merged.
This has been observed in .

Note:For collision meshes modeled in Blender or Softimage Mod Tool, ensure that none of the edges are marked as hard/sharp. Hard/sharp edges generate errors in the physbox model.

Tip:Set the Console Variable vcollide_wireframe 1 to view collision meshes in-game.

Syntax

$collisionmodel	<collision mesh SMD/DMX>
{
	<options>
}

Options

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Note: Missing parameters for some options

$mass <float|kilograms>

Manually set the mass of the model, in kilograms.

Tip:By default, the Player can +USE pick up 35KG max. The gravgun can pick up 250KG max. The portal gun can pick up 85KG max.

$automass

Calculate the mass of the model based on the volume of the collision model and the material defined in its prop_data.

$concave

By default, studiomdl will generate a single convex hull by 'shrinkwrapping' any concavities. You can create a concave hull by including multiple convex shapes (potentially overlapping) in your collision model, smoothing the hulls’ shading, and passing this command.

$maxconvexpieces <int> (in all games since )

By default, the model compiler limits a concave collision model to twenty convex pieces. This command can be used to override the limit if you are creating a Costly collision model.

Note:Introduced with the Orange Box. In the Ep1 engine, run studiomdl with -fullcollide instead.

Warning:Going past a hundred or so pieces may begin to create server lag when multiple objects are touching the model.

$masscenter <vector|offset>

Override the center of mass, in local coords.

$inertia <normal>

Inertia scale. Higher values will make the physics object more sturdy, while lower values will make it more wobbly.

$damping <float>

Linear damping scale. Affects how quickly an object's velocity drops to zero.

$rotdamping <float>

Rotational damping scale. Affects how quickly an object's angular velocity drops to zero.

Warning:This affects the pull of gravity on the model and if abused can make it appear to float gently through the air. Valve recommends using "friction" instead.

$drag <normal>

Scales air resistance. Essentially a more subtle version of $damping.

$jointskip

Rarely used. Eliminates a joint in the collision model that you don't want to use. (i.e. if you were using a render model as a ragdoll, and it has bones you don't want).

$jointmerge

Merges the vertex assignments for two joints.

$jointinertia

Like $inertia, but per-bone.

$jointdamping

Like $damping, but per-bone.

$jointmassbias

Mass is automatically distributed by volume, this lets you bias it per-bone.

$jointrotdamping

Like $rotdamping, but per-bone.

$jointcollide

If any $jointcollide pairs are specified, only those joints collide with each other.

$jointconstrain

The limits of the joint's movement.

$rootbone

The parent-most bone that actually has collision geometry.

$noselfcollisions

Turns off all collisions between bones in this model.

$animatedfriction

Used to animate the amount of friction on joints over time.

$addconvexsrc <file> "offset pos[ <float> <float> <float> ] angle[ <float> <float> <float> ] scale[ <float> ] concave" (only in )

Adds a convex model onto the collision model with the specified position, angle, and scale. The "concave" option is optional.

Note:It must be formatted EXACTLY like this!

$remove2d

Used to remove flat shaded faces. Off by default.

$weldposition <float>

The amount of distance tolerance to use when trying to merge vertices of separate concave pieces in order to create a single concave piece.

$weldnormal <float>

The amount of tolerance to check if the vertice normal is similar enough to consider merging to a unique vertice. Used in conjunction with $weldposition.

$assumeworldspace

Assumes the joints are positioned in world space.

Example

$collisionmodel "tree_deciduous_01a_physbox"
{
	$mass 350.0
	$concave
}

See also

• Collision mesh
• $collisionjoints
• Costly collision model
• VPhysics
• Physics and Ragdolls