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This operator transfers attributes (such as normal direction) from some referenced geometry to the input particles.
Vertex attributes are changed to point attributes for the particles if necessary. All vertices referencing a particular point are considered a single sample and the value of the first one is used as the sample value.
You can choose which attributes are transferred with patterns in the Points and Vertices parameters on the Attributes tab.
This operator can use two different methods for controlling when and how attributes are transferred, controlled in the Conditions tab.
Turns this node on and off. The node is only active if this value is greater than 0. This is useful to control the effect of this node with an expression.
Note that this is activation of the node as a whole. You can’t use this parameter to deactivate the node for certain particles.
Specifies the SOP to use.
Use Parameter Values
Use the SOP specified in the SOP parameter below.
Use First Context Geometry
Use the SOP connected to the POP network’s first input.
Use Second Context Geometry
Use the SOP connected to the POP network’s second input.
Use Third Context Geometry
Use the SOP connected to the POP network’s third input.
Use Fourth Context Geometry
Use the SOP connected to the POP network’s fourth input.
Path to the SOP (when Geometry source is set to Use Parameter Values).
Ignore Transform Object
Particles normally use the object space of the SOP being cooked. Turn this parameter on to not transform into the space of the cooking SOP.
Subset of the referenced geometry to use. Either a group pattern or a named group (created by a Group SOP) can be used.
SOP Group Type
How to interpret the SOP Group parameter
Interpret the string as a primitive group.
Interpret the string as a point group.
Choose which attributes are transferred with patterns in the Points and Vertices parameters.
To transfer all available attributes, leave the field blank or set it to a single asterisk (
To exclude attributes, prefix an attribute name with the caret character (
If the first attribute is preceded by a caret (
^), all attributes are assumed to be transferred except where explicitly excluded. Otherwise, no attributes are assumed except where explicitly included.
List of names/patterns of point attributes to transfer. Turn off the checkbox to avoid transferring any point attributes.
List of names/patterns of vertex attributes to transfer. Turn off the checkbox to avoid transferring any vertex attributes.
This tab lets you choose between two methods (Weighted average and Smoothed particle sampling) to control when and how attributes are transferred.
This tab displays different parameters depending on which method you choose.
Destination attributes are interpolated from the source attributes using a weighted proximity technique. Attribute calculations use the distance between the destination point and the candidate source points.
Smoothed particle sampling
This mode is based on the SPH (Smoothed Particle Hydrodynamics) model. This is a specialized model of attribute transfer useful in certain technical situations.
Each attribute is sampled using the formula:
A(r) = Sum(over all j) (m\[j] * A\[j]/p\[j] * Wh(r-r\[j])
You might want to use the SPH model when you need to sample some physical quantity (say, temperature) at an arbitrary location in a space (generally a gas, liquid, or solid volume) and you have a discrete sampling of that quantity.
You would not use it when doing things such as grabbing colors from geometry, but you might want to use it if, for example, you are estimating a force vector within a wind tunnel at an arbitrary point given some spatial sampling of the force field.
Interpolating metaball kernel . The kernels are parameterized by distance and typically give more weight to samples that are closer.
Radial extent of the kernel function. Specifies the drop-off radius for the kernel function. As the kernel radius parameter approaches zero, the filter resembles nearest neighbor interpolation. As the kernel radius parameter increases, the filter approaches uniform weighting.
Max Sample Count
Number of closest samples to interpolate from. specifies the maximum number of samples to interpolate from. A maximum sample count of 1 gives nearest neighbor interpolation.
Radial extent of the filter domain where the final attributes are determined from the source selection only. Specifies the maximum distance source points must be to be considered. Turning off this option indicates that no points/vertices will be excluded based on distance.
Initialize Attributes to Zero
Zero attributes when there are no samples. Attributes will be set to zero if no samples are found, otherwise, the attribute will maintain the previous value.
Smoothed particle sampling
SPH Kernel Function
Normalized smoothing function. Specifies the normalized smoothing kernel to use.
SPH Kernel Radius
The extent over which the samples are smoothed. Samples outside this radius do not contribute. specifies the maximum distance over which the kernel acts. The actual radius h used above is computed based on this value for each kernel.
An attribute that is used as a coefficient of the term
for a sample in the sum. Specifies the name of the point
attribute on the sample geometry to use as the
m[j]/p[j] factor in the SPH formula.
Standard POP local variables
The seconds a particle in the template has been alive.
AX AY AZ
Acceleration of the particle.
BBX BBY BBZ
The point’s relative position in the bounding box.
Point is dead.
Processing iteration number.
A collision for this particle was detected (for example, by the Collision POP) during the processing of this timestep (that is, this iteration of the particle simulation). This variable is cleared at the beginning of each timestep. Note that the collision POP actually detects any collisions which would have occurred the during the previous frame.
Percent of total life used (from 0 to 1).
Expected lifetime of particle.
MAPU MAPV MAPW
Point or vertex texture coordinates.
Total number of points.
Total number of points in source group.
NX NY NZ
The point number of the currently processed point. The
PT is not constant like
ID; it changes based on the number of points.
RESTX RESTY RESTZ
The rest position.
The sliding state of the particle.
Elasticity of a point.
Point is stopped.
1 if particle is stuck to a collision object.
TX TY TZ
Surface UV values.
VX VY VZ
Point spline weight.
Distance from particle to last collision.
HCR HCG HCB
Diffuse color at the collision point on the surface the particle collided with.
ID for last collision. You can control how this attribute is set in the Collision or Limit POP to help distinguish types of collisions.
The time at which the last collision occurred.
The texture map UV coordinates for the surface location where the last collision occurred.
HNX HNY HNZ
The normal at the surface location where the last collision occurred.
HTX HTY HTZ
World space position of the last collision.
The UV coordinates for the surface location where the last collision occurred.
Number of times the particle has collided.
Added by Color POP
Point or vertex alpha value.
CR CG CB
Diffuse point or vertex color.
Added by Property POP
Charge of the particle.
Point is clinging to geometry.
Leader to follow.
SCALEX SCALEY SCALEZ
Added by Proximity POP
Either the point number or id of the particle nearest to this one.
The distance to the nearest particle.
The number of particles within a specified proximity to this particle.
Added by Rotation POP
ROTX ROTY ROTZ
Added by Source POP
ID number, which always remains constant.
Original Source point was birthed from.
Parent’s ID Number.
Added by Speed Limit POP
Added by Sprite POP
Sprite rotation around view axis (in degrees).
Texture coordinate of sprite’s lower-left corner.
Size of sprite in texture space.
Controlled by Suppress Rule POP
Suppress default position rule.
Suppress default velocity rule.
Suppress default up-vector rule.
Suppress default aging rule.
1 if particle is suppressing its default rotation rule.
1 if particle is suppressing its default angular velocity rule.
Added by Up Vector POP
PVX PVY PVZ
UPX UPY UPZ
Absolute speed of particle.