The Scale operator allows you to control the size of particles.
Absolute: particle scales will be set to a user-defined absolute value.
Inherit previous: uses the current value of a particle’s scale as the starting point, prior to modifications.
Relative add: add a user-defined scale value to the current value of the particle’s scale.
Relative multiply: multiplies the current value of the particle’s scale by a user-defined vector.
Relative first: multiplies the value of the particle’s scale when it first entered the operator by a user-defined vector.
Scale by velocity: constructs a scale vector for each particle using its velocity as a multiplier along each axis. The multiplier is applied to the scale of the particle when it enters the event. Scale X/Y/Z values set to 0 will maintain the original scale of each particle.
Scale by Sibling Distance: the z-axis of the particle’s scale vector will be set to the distance between the particle and its adjacent sibling.
Scale by Target Distance: the z-axis of the particle’s scale vector will be set to the distance between the particle and its target.
The effect of the absolute values on a particle’s scale depends on which scale type is selected.
X/Y/Z %: the amount of variation to apply along each axis of the intermediate scale values.
Uniform: the variation applied along each axis will be uniform, preventing proportion skewing.
The texmap rollout allows you to control particle scales by sampling textures on nearby surfaces and multiplying scales by the resulting values. The darker the sampled texture value, the smaller the scale multiplier.
Multiply by texmap: controls whether texmap scaling will be enabled.
Texmap: the texture map to sample.
Nearest Object: UVW coordinates will be sampled from the surface of the nearest object in the object list.
Particle: UVW coordinates will be taken from each particle’s mapping channel.
Surface offset as W: the distance from the particle to the closest surface will be used as the W coordinate in the UVW value which is used to sample the texture.
Object list: the list of objects whose surfaces will be sampled for UVW coordinates.
Sample: controls which sampler will be used for surface proximity tests.
Affect X/Y/Z: provides control over the amount of influence a texmap will have on each axis of the resulting scale vector.
Invert: inverts the effect of the texmap scaling.
The proximity rollout allows you to control particle scales by measuring distances to nearby scene objects and their surfaces, and multiplying scales by the resulting values.
Multiply by proximity: controls whether proximity scaling will be enabled.
Radial XYZ: proximities will be calculated in 3D space.
Axial X/Y/Z: proximities will be calculated on the specified 3D plane in 2D space.
When performing axial proximity tests, the specified axis will be ignored in the proximity calculations. For example, if you want to multiply scale by the proximity of particles to an object along the world X/Y axis, while ignoring their relative proximity along the Z-axis, specify Z-axis as the axial plane.
Distance: particles within this distance will be fully affected.
Falloff: the effect on particles beyond the base distance, but within this falloff distance, will diminish according to the inverse-square law.
Invert: inverts the affect of the proximity scale multiplier.
Object list: the scene objects used to calculate proximity multipliers.
Sample: controls which sampler will be used for surface proximity tests.
The noise settings allow you to offset the way in which particle positions are measured during the proximity test.