Collision Attribute

In the Collision attribute, specify how to control the particle's physical setup.

CPU Collision Attribute Parameters
Name	Description
Physics Type	Specifies how the particle interacts physically. None – No collisions or other physics. This setting is used by default. SimpleCollision – Collides the particle with the static environment using simple physics. This is the simplest mode. SimplePhysics (Geometry particles) – Creates a particle in the physics system and collides using a spherical particle model. Use Surface Type to set the bounciness. RigidBody (Geometry particles) – Creates a particle in the physics system and collides using the full collision mesh of the assigned geometry. This is the most expensive mode. Use Surface Type to set the bounciness.
Collide Terrain	Includes terrain in particle collisions. Default value: false
Collide Static Objects	Includes non-terrain, static objects in particle collisions. This is expensive. Default value: false
Collide Dynamic Objects	Includes non-terrain, dynamic objects in particle collisions. This is expensive. Default value: false
On Collide	Upon impact with the static environment, the particle dies. Die – The particle dies upon colliding with an object. Bounce – If you enable Collide Terrain, Collide Static Objects, or Collide Dynamic Objects, the particle bounces off the respective type. If none of these are enabled, the selected particle ignores the object that it collides with and passes through. This is useful with Spawn Indirection – Parent Collide. Stop – The particle stops when it collides with an object. Default value: Die
Max Collision Events	Limits the number of collisions that the particle can have in its physics simulation. This affects only particles that have Physics Type set to Rigid Body. Valid values: 0 to 255 Default value: 0
Bounciness	Controls the elasticity for collision response. This affects only particles that have Physics Type set to Simple Collision. You can override this feature by setting Surface Type. You can also use a special value of –1 to have the particle die on first collision. Valid values: any Default value: 0
Collision Fraction	Determines the fraction of emitted particles that perform collisions. Valid values: 0 to 1 Default value: 1
Collision Cutoff Distance	Specifies the maximum distance from the camera at which collisions are performed. A value of 0 means infinite. Valid values: 0+ Default value: 0
Surface Type	Selects from a variety of surface material types for the collision behavior. If set, Surface Type overrides Bounciness and Dynamic Friction. Default value: none
Dynamic Friction	The coefficient of dynamic friction. If set, Surface Type overrides Dynamic Friction. This affects only particles that have Physics Type set to Simple Collision. Valid values: 0+ Default value: 1
Thickness	Controls the fraction of the particle's visible radius to use for the physical radius. This affects particles that have Physics Type set to Simple Physics and geometry particles that have Physics Type set to Simple Collision. Valid values: 0+ Default value: 1
Density	Controls the particle density in kg/m^3. An example of a physically correct value is Water = 1000. This affects only particles that have Physics Type set to Simple Physics or Rigid Body. Valid values: 0+ Default value: 1000

GPU Collision Attribute Parameters
Name	Description
Depth Collision	Specifies how the particle interacts physically. None – No collisions or other physics. This setting is used by default. Frame Buffer – Collides with the screen space depth buffer. Cubemap – Collides with a depth cubemap buffer that is generated around the emitter.
Cubemap Far Plane	Sets the far plane distance for cubemap depth buffer generation. Default value: 20
Die on Collide	Upon impact with the static environment, the particle dies. Die – The particle dies upon colliding with an object. Bounce – The particle bounces off the object that it collides with. Stop – The particle stops when it collides with an object. Default value: Die
Bounciness	Controls the elasticity for collision response. This affects only particles that have Physics Type set to Simple Collision. You can override this feature by setting Surface Type. You can also use a special value of –1 to have the particle die on first collision. Valid values: any Default value: 0
Thickness	Controls the fraction of the particle's visible radius to use for the physical radius. This affects particles that have Physics Type set to Simple Physics. Valid values: 0+ Default value: 1