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Connect the output of a Capture Metaball SOP that uses muscles as its capture regions to the input of this node. This node deforms the captured skin geometry as the muscles deform using the attributes created by the Capture Metaball SOP to determine which surfaces are controlled by which metaball groups. Muscles are created using the Muscle Object.
This deformation occurs in two stages. First, the skin geometry is deformed according to the positions of the metaballs contained in each muscle (see also Deform Metaball). Next, the skin geometry is inflated over the muscle surface (see also Inflate) so that the shape of the muscles is preserved by the skin.
Muscles are generated using blended metaballs. The density of each metaball where it captured to the skin geometry at the capture frame controls how much influence the metaball has when it deforms the skin geometry. This density is multiplied by the weight of the group that metaball is contained in. Group weights are specified by the Capture Metaball and Capture Layer Paint nodes. Group weights are also used by this operator to determine which muscles influence each point during inflation.
This tab controls point deformation. In this stage, input points are deformed according to changes in the captured muscle structure.
Normalize Group Weights
Normalize group weights before performing the deformation.
Calculates point normals before doing anything. You can use these normals with Deform Normals.
Deforms point normals to match the deformation of the points. This can help keep normals pointed correctly after deformation.
Deform Vector Attributes
Deforms vector attributes to match the deformation of the points.
Vector attributes to deform.
Deform Quaternion Attributes
Deforms quaternion attributes to match the deformation of the points.
Quaternion (Float\/nodes/sop/4) attributes to deform.
Position Bias Multiplier
Increasing this parameter biases the capture weights of points more towards metaballs that are close to that point’s capture position. It can be used in conjunction with the Capture Position Bias parameter on the Muscle Object. This parameter acts as a multiplier to the muscle specific Capture Position Bias parameter in the Muscle Object. Increase this parameter to reduce the effective radius of influence of metaballs on surrounding points during deformation. Decrease this parameter to increase this radius of influence.
Assume Only Coordinate Changes In Input
Enables the assumption that only point positions need to be re-cached when the input geometry has changed to allow faster cooking. Unpredictable results will occur with this enabled if attributes or topology changes.
This tab controls point inflation. In this stage, points are optionally inflated to lie on top of the captured muscle geometry.
Enables or disables the inflation step of the deform process. If inflation is disabled, then the captured geometry is deformed according to the underlying muscle positions but is not inflated to lie on top of the muscle surface.
Points To Inflate
Specifies which points in the input geometry should be influenced in the inflation step.
Inflate All Points
All points in the input geometry may be inflated.
Use Inflate Modifier Attribute
The Slide Modifier Paint operator may be used to paint a "Surface Inflation Modifier" attribute using the Attribute to Paint parameter on this node. This attribute is used to determine how to inflate points in the input geometry when "Use Inflate Modifier Attribute" is specified. This float attribute may take any value between 0 and 1. A value of 0 specifies that a point should remain at its deformed position without inflating. A value of 1 specifies that a point should be transformed to its fully inflated position. Values in between 0 and 1 blend linearly between the two positions. This option can be used to specify exactly what locations of the input geometry require inflation.
Muscles For Inflation
Use this parameter to specify a list of muscles over which the input geometry is to be inflated. Points in the input geometry will only be inflated over the muscles in this list.
The maximum distance that a point can be pushed away from its original position. If a muscle cannot be found within this distance, the point is kept at its original position.
This controls the tolerance used when trying to locate a position on the muscle surface to place each point in the deformed geometry. A higher tolerance can provide increased performance, while a lower tolerance results in a smoother skin surface. In general, a higher tolerance such as 0.01 is sufficient for interactive work, while a lower tolerance such as 0.0001 is more appropriate for animation.
The points in this group will be considered joint points, and so special consideration for them will be given when inflating and Exclude Opposing Metaballs for Joint Group is enabled. When a point is in a joint group, it will not be inflated to any metaballs whose normals point in an opposite direction to the point’s normal. This is especially useful for points in the inside curve of a joint because it will keep points from inflating to a muscle on the opposite side of the joint. The Group Paint SOP can be used to easily paint this group. Alternately, inflation can be avoided entirely in the inside of a character’s joints by setting Points to Inflate to "Use Inflate Modifier Attribute" and painting points such that these points are not inflated.
Exclude Opposing Metaballs for Joint Group
Checks to make sure that a metaball’s normal and the point normal for a given point are not pointed in opposite directions. If they are, the point should not be inflated to that metaball, since it is on the opposing side of the joint. This option turns this check on or off for points in the joint group.
If this parameter is enabled then the Deform Muscle SOP simulates the effect of skin sliding over top of the underlying muscle surface. For this to work, each Muscle Object to which the geometry is captured must define a rest anchor.
The amount of sliding to allow during deformation. If this parameter is set to zero, then points in the captured geometry stick perfectly to the muscle surface during deformation and no sliding occurs. If this parameter is set to one, then points do not stick to the underlying muscle surface at all, and the skin slides freely over the muscles. This parameter may be modified on a per-point basis using the Slide Modifier Paint operation.
This tab controls geometry smoothing. It can optionally be used to smooth out portions of the input geometry that have deformed or inflated in an undesirable way. See also the Smooth SOP.
Enables or disables geometry smoothing.
Primitive Group to Smooth
Use this parameter to specify a primitive group in the input geometry to perform the smoothing operation on.
Smoothing Cutoff Frequency
Noise frequency to remove. The larger this value, the more it will keep the original shape of the geometry.
Number of smoothing steps.
When this parameter is set to 0, points on the boundary of the group specified in Primitive Group to Smooth may also be affected by the smooth operation. Setting this parameter to 1 clamps this points to remain in their original position. Values between 0 and 1 blend the boundary point positions between their un-clamped and fully clamped positions.
The deformed geometry.