Shape operator

The Shape operator allows you to assign meshes to particles.


Shapes

  • Shape list: the list of possible shapes that will be assigned to particles.

Select an existing item in the shape list to modify its properties.


Shape properties

Distribution
  • Frequency: the distribution frequency of a particular shape in the list.

As particles enter the operator, the shape they are assigned depends on the frequency values of shapes in the list. For example, if one shape has a frequency of 10%, and a second shape has a frequency of 90%, there will be a 10% chance that particles will be assigned the first shape, and a 90% chance that particles will be assigned the second shape.

You do not need to ensure that all shape frequencies add up to 100%. Their values will be normalized automatically if they do not all add up to 100%.

Size
  • Override scale: controls whether to override the scale of particles which are assigned the shape.

  • Scale %: the scale override.

  • Variation %: the per-particle percentage of variation to apply.
Mesh Type
  • 2D: controls whether the shape will be selected from a list of preset 2D meshes.

  • 3D: controls whether the shape will be selected from a list of preset 3D meshes.

  • Reference object: controls whether the shape will be referenced from a scene object in the scene.

  • .vrmesh file: controls whether the shape will be loaded from an existing .vrmesh file.

  • Load full mesh in render only: when enabled, only preview geometry will be displayed for loaded .vrmesh data in the view (this can drastically speed up viewport performance for high resolution proxy files).

.vrmesh files must be exported with preview geometry enabled, in order to display it in the viewport. Preview geometry settings are available in the standard .vrmesh exporter provided by Chaos Group.

Mesh Settings
  • Split group members: if the shape is referenced from a scene object, and the scene object is a group head, the assigned shape will be chosen from a random child of the group head.

When selecting a group as the reference object, make sure you select the bounding group head object, not a member of the group itself. The group head is denoted in the viewport as a colored bounding box around the group members, and can be displayed by selecting the closed group and choosing Group->Open from the 3ds Max Group menu.

  • Split mesh elements: if the shape mesh has child elements, the assigned shape will be a random child element of the mesh.

  • Center pivots: moves the shape’s particle offset to its center.

  • Material ID Override: overrides the material ID of the particles the shape is assigned to with a random material ID within a range of specified values.

  • Min/Max: the min/max range of potential material IDs.

  • Animated Geometry: controls whether animated deformations of the shape will carry over onto particles that are assigned the shape.

  • Update in render only: controls whether animated deformations of the shape are only updated at rendertime. This allows for faster viewport updates.

  • Animation sync: controls the offset timing of animated deformations.

Event age: the start frame of the animation will be synced to the event age of the particle.

Particle age: the start frame of the animation will be synced to the age of the particle.

Frame: the start frame of the animation will be synced to the current frame of the timeline.

  • Default frame: the default frame that will be loaded in the viewport when “update in render only” is enabled.

  • Start frame: the start frame of the animation to reference.

  • End frame: the end frame of the animation to reference.

  • Rand offset: the per-particle random starting offset within the start/end range of the animation.

  • Speed: the per-particle animation playback speed multiplier.

  • Variation %: the per-particle percentage of variation to apply.
  • Loop: controls whether the animation will loop back to the start frame once the end frame is reached, during sync.

Vray Instance Mtl Override
  • None: no material override will be assigned to render instances of this shape.

  • Inherit from reference: the material override for render instances of this shape will be taken from the scene object it is referencing.

  • Scene Material: the material override for render instances of this shape will be the specified material.

  • .mat file: the material override for render instances of this shape will be the first material present in the specified material file.

Distribution
  • Random by frequency: each particle will choose a shape from the list randomly, taking into consideration each list entry’s frequency parameter.

  • Index from custom float value: each particle will choose a shape from the list, using a custom data float value as an index to the listbox’s entry array.

  • Channel: the custom data float channel to use for the index value.

Use “index from custom float value” to specifically choose which shape from the list each particle will be assigned. Doing this will allow you to choose the same shape for each particle across multiple Shape operators in the flow.

Uniqueness

  • Seed: the seed value for all varied parameters.