'No compatible' exactly means no-compatibility of nodes/compounds inside the same ICE tree, or connected ICE trees. What is on another, independent Point Cloud in the same scene, this doesn't matter. So it's harmless to use work done with different versions, all in the same scene - as long there is no ICE connection in between.
How the system works, this can be compared with rigging system. Sometimes, nodes/compounds from system can be 'misused' for another purposes, but generally, misusing means a huge overhaul.
Basic knowledge of ICE is required (how to connect the nodes, what is un-simulated ICE tree, what is Cutoff distance ...) - as well as basic knowledge about transformations (what is Up Vector, what is Reference pose...).
Create an empty Point Cloud, create un-simulated ICE tree, bring "kH Emit From NURBS" or "KH Emit from PolyMesh" node to ICE tree.
If emitter is poly mesh: frozen, non-overlapped UV property should exist on mesh. Also, ICE tree on mesh, with kH Initialize Mesh Emitter node. For some nodes, such as kH Fur or kH In Between Curves, tangent property should go on mesh as well.
Also, node creates basic point and strand attributes, such as point color, point and strand size, count of strand segments. Initially, strands are aligned to point normal of NURBS surface. Particle shape type is set to segment. All attributes can be changed later, except one: count of strand segments, which is the same for all points in point cloud, all the time. Even hair filler node will re-use this value.
Important parameters:
- Emission mode: 'Guides and Filler' creates a virtual grid of triangles, one point is created on each corner of virtual triangle. Three strands on each triangle are used later by filler, in order to create a final hair for rendering.
'Random' is a random distribution along NURBS surface. In this mode, filler is automatically disabled, even if there is active filler node in ICE tree.
- Chunks Rate: Number of virtual triangles.
- Fit Border, Turbulence, Frequency: parameters for distribution, explained in image bellow.
- XY Ratio: In case of 'Guides and Filler' mode, this parameter can change distribution, more point along X, less along Y, and reverse.
- Seed: It's the same for both emission types.
- Final Rate: In case of 'Guides and Filler' mode, this tells to filler how many points to emit, in case of 'Random' mode, that's a count created by kH Emit From NURBS node.
- Segments: Count of strand segments.
- Size: Particle size. This is for all strand segments too. Variable strand size can not be set with this parameter.
- Initial Length: Initial strand's length. Usually this overriden by styling nodes. However, it always suplies a valid strand for rendering.
- First Segment: Relative position of first strand segment, at zero it's close to point/hair root, but never on the same position.
- Density: Sliders for adjusting the emission density, along X/U and Y/V of emitter.
Important parameters:
- Emission mode: 'Guides and Filler from Triangles' creates a point is on each corner of poly mesh triangle.
In 'Guides and Filler' mode, emitter mesh should be 'triangulated', for proper emission.
'Random' is a random distribution along poly mesh, using a factory 'Generate Sample Set' node. In this mode, filler is automatically disabled, even if there is active filler node in ICE tree. 'Random' emission works properly from any kind of polygon mesh.
- Seed: It's the same for both emission types.
- Final Rate: In case of 'Guides and Filler' mode, this tells to filler how many points to emit, in case of 'Random' mode, this is a count created by node itself.
- Segments: Count of strand segments.
- Size: Particle size. This is for all strand segments too.
- Init Length: Initial strand's length.
- First Segment: Relative position of first strand segment, at zero it's close to point/hair root, but never on the same position.
- Reference to texture projection: should point to 'UVs' attribute.
Picture: suitable mesh for 'Guides and Filler' emission mode has as much even distributed triangles. Non-overlapped, well unfolded UV projection is required too. This one is created from high-res subdivision, using a SI 'Filter Points' operator, also a bit of cleaning by hand.
Optional NURBS surface input: in case emitter is NURBS, it can be plugged here, to enable points/hair root to "stick" to emitter, instead of linear interpolation in between of three points.
Parameters:
- Density: rate multiplier, 'Modulate by weight map' factory node can go there.
- Seed: seed for random distribution
- Distribution: see image bellow
Important parameters:
- Nb to clone: number of cloned points. It's the same number for all original points.
- Splay : factor of moving in SI units.
- Clump: moves strand back to original positions.
distributed along normals, or in between two NURBS. There is a 'blending area' for creating smooth interpolation, from point positions (hair roots) to flow.
Two functions (filtering the closest location, and 'shaping source') can be assigned to different NURBS surfaces.
Filtering NURBS surface need to be *close* to points/hair roots, inside cutoff distance.
Important parameters:
- Mode: 'Interpolate' is the same function as a former kH Follow NURBS 2 - strands are interpolated in between 'filtering' and 'shaping' NURBS surface. "Push from Shaping" and "Negative Push From Shaping" is distribution along normals of 'shaping' NURBS.
- Blend End: end of 'blending area', along relative strand's length.
- Blend Type: 0 is exponent, 1 is smooth step.
- Length: End of strands, along X of NURBS surface.
- Width Y parameters: Scale and center of scaling, along Y of NURBS surface.
- Push: Scaling of strand's flow, along surface normal. Too high values, together with highly curved NURBS, can produce artifacts. In case of "interpolate" mode, parameter has no effect.
- Shift: It moves whole flow along surface normal's. Too high values, together with highly curved NURBS, can produce artifacts. In case of "interpolate" mode, parameter has no effect.
- Set Parting Line > Sample Offset: in case boundary of 'filtering NURBS' is close to itself, there is a chance for finding the locations on wrong side. If sampled "V" is higher than "V threshold", third sample is activated. This sample is defined by direction between chunk and point position. Inverse of direction is used as UV sample, which is always on the same side as chunk sample. Default "V threshold" value should be adequate, all the time.
- Limits: Outside these limits, node has no effect. In case of overlapped influences of multiple kH Follow NURBS nodes, the last one has a precedence.
- Cutoff Distance is a maximum distance from points/hair roots to locations on NURBS surface.
- X min, Y min and Y max: outside these limits, locations are ignored. Usually NURBS surface is 'aligned' to emitter. Ignoring the locations outside these limits, removes the points/hair roots which aren't "bellow" the filtering NURBS. It's good idea to keep values different than min 0 or max 1, for better interpolation.
- Alternative Strand Array: Additional input for modifying the flow. Input is only for 'kH Offset by NURBS ...' nodes.
- 'Offset Null' input is for null (or anything else which has SRT), which serves for defining the virtual UV space. It's good idea to parent the NURBS surfaces under this null, so you'll be able to move-scale-rotate everything at once.
Important parameters:
- Clump and Locks: node is able to create procedural interpolation. Count of stripes is relative to distance between Y boundaries, at zero X.
Picture shows how a null local space defines the UV and "Z" space of "main" kH Follow NURBS.
For getting correct vectors for later deformations, it's good idea to keep NURBS surfaces as much perpendicular to flow - at least in areas where deformations should be applied. For correct effect of modifiers that are used later, NURBS cross sections should be at equal distances - except first and last segment, that should be two times shorter.
Important parameters:
- Cut Last: removes some of last NURBS surfaces from calculation.
- Length: End of curve creation.
- Cutoff Distance: Maximum distance to 'filtering NURBS'.
- Mid Point: if it's enabled, node will add additional point between hair root and location on first NURBS surface. 'Position' is relative in-between position. 'Push' is a relative scaling along point normal of emitter,'Shift' is moving along point normal.
In case of multiple curve inputs, later one overrides the previous, in area of influence
Important parameters:
- Distance: Distance for limit the effect, in SI units.
- Clump: moves the strands closer to curve.
- Align To Tangent: aligns strand along curve. Emit Point Normal is used as Up Vector, strand tangent as 'point at' of 'Direction To Rotation' node - so it is supposed to works somewhere in hemisphere deined by Emit Point Normal - still outside of parallel Emit Point Normal and strand tangent.
Important parameters:
- Scale: Scaling of whole fur profile.
- Fill: Scaling along profile.
- Bend: bends the profile
- Rotation: Around point normal, and X axis of UV space of NURBS emitter.
- UV direction: for polygon meshes, Y is 'vertical' looking from UV space.
- Reference to tangent map property, in case of poly mesh emitter: should point at 'Colors' attribute.
Important parameters:
- Interpolate around: if is enabled, samples are virtually aligned on UV planar space, interpolated and aligned back to original orientation.
- Reference to UV property, in case of poly mesh emitter: should point at 'UVs' attribute.
- Two references to tangent map property, in case of poly mesh emitter: should point at 'Colors' attribute.
For calculations, node is using exact strand positions, instead of interpolations in between - when tweaking parameters, or modifying the count of strand segments, that will produce effect of 'jumping'. But once the deformation is set, effect of node should stay stable.
Important parameters:
- On Length: Starting position of effect, relative to strand length.
- Scale: Scale of whole effect.
- Bend Angle: Maximum angle of rotation. It's limited to -360 + 360 degree.
- Roll: Rotates a whole deformation, using the first strand tangent of deformation, as an axis.
- Circle profile function curve - it can deform the circle.
- Distribution: In case of "Align To Follow NURBS", adjusts the starting point of influence, so even hair roots aren't aligned, starting positions of modifier's effect *are* aligned. Effect is visible if kH Follow NURBS is used before.
Important parameters:
Locks: guides are aligned in stripes of the same width. If 'Fixed Lock Size' is active, that's a width In SI units, otherwise that's a width at origin.
Clump: moves the guides to average position of emitting triangle.
Crossover start, crossover length: similar to options in default SI hair shader, but crossover length is added to crossover start.
Important parameters: adds Raycasting to computation, measuring the distance between the last 'in' and first 'out' segment.
Important parameters:
- Weight: 'radius' in SI units.
- Shift XY: it's in SI units. Whole effect is moved, this is mainly for avoiding penetrations with model's body.
- Factor XY: multipler of radius for local X and Y direction.
- Nb Curls: Number of circles. It's per point value, so it can be randomized only per point, not along strand length.
- Exponent: At more than one, rotation is stronger at hair tips. Less than one is reverse.
- Add Nb: Moving the curls along relative strand length.
- Distribution: In case of "Align To Follow NURBS", adjusts the starting point of influence, so even hair roots aren't aligned, starting positions of modifier's effect *are* aligned. Effect is visible if kH Follow NURBS is used before.
- Count X and Count Y: Number of groups along. It's approximation, it can be slightly different than input.
- Randomize: Proportional randomizing of diagonal grid.
- Clump, Crossovers: the same as is in other modifiers.
- Set What: In case of 'Group ID', node sets only ID for each group. ID can be used later with 'kH Random Value' node.
Parameters:
- Segments: count of used positions. Should be smaller than original strand count.
- Form node X: in case of applying after 'Follow Nurbs', takes only points, close to parting line.
- Rotation: rotates along first used strand tangent
- Weights: X is cross product od strand up vector and tangent, Y is up vector, Z is tangent.
Important parameters:
- Type: Direction taken from null's Y axis, look at null, circle around null. For curves, direction is curve's tangent.
- Negate: inverts direction.
- Distance: multiplier of distance in SI units. Inside this distance, weight is 1.
- Falloff: Fallof, added to distance.
- Project To Surface: it does 'Point To Plane Projection', that forces strands/hairs to keep the original direction along emitter, instead of taking from null.
Important parameters:
- XYZ weight: it's in SI units.
- Blend End - position on strand, relative to strand length, where modifier has a full effect. At hair root, there is no any effect.
Important parameters:
- every Nth: limits the effect every nth point/strand array in point cloud.
- Blend End: reaches the full weight, according to relative strand length
Important parameters:
- Shift Center: moves the turbulence effect along relative strand length.
- Randomize: Adds random value to UV values from emit location, providing a 'total' random effect, per point. Keep it at zero for aligned turbulence.
- Scale UV: this will virtually scale UV values from emit location, providing a different turbulence frequency per point, but still continuous. Scaling of this value will exaggerate 'random per point' effect. Keep it at zero for aligned turbulence.
- Distribution: In case of "Align To Follow NURBS", adjusts the starting point of influence, so even hair roots aren't aligned, starting positions of modifier's effect *are* aligned. Effect is visible if kH Follow NURBS is used before.
Important parameters:
- Randomize: additional, per point random effect, for creating a 'total' random effect, per point
Important parameters:
- Factor: scaling factor, along relative strand length.
Node can be used anywhere.
Important parameters:
Factor: Multiplies the count of strand segments. Here, kH Subdivide Strands behave differently than XSI geometry approximation. For example, with factor 3 and original count of 21, result is 63. With factor 5, result is 105, and so on.
Important parameters:
Type: 'Emit Location' is UV value from NURBS emitter.
'By Modifiers' is UV value provided by 'form' nodes - for example, UV value from 'Closest NURBS' used by kH Follow NURBS.
Important parameters:
- Multiply: multiplies color by scalar value. This can be used to display useful information for styling - for example, kH UV fCurve can be plugged into this input.
- Alpha: if gradient color is used, it seems that is impossible to get alpha on point color, in view ports. So, node will re-build color internally, and apply a new alpha.
- Turbulence frequency, complexity, seed: common parameters of factory Turbulence node.
- XY Ratio: Scales the underlying UV values.
Important parameters:
- Function Curve
Important parameters:
- Screen Resolution: Horizontal pixel resolution of rendered image
- SI Size: Desired strand size in SI units. It's strand array, so kH Strand fCurve node can be plugged here.
- Minimal Screen Size: for avoiding anti-aliasing artifacts, node is able to keep minimal screen size to entered value.
Built in Random Value is for smooth weighting of deleting effect, that follows weight map values.
kH Point Dynamics Init Sim node is for creating initial attributes. Typically, it should go at the end of ICE tree, which begin with kH Emit Guides.
Important parameters:
On Length: position on strand, used for creating direction. 1 is end of strand.
Important parameters:
- Angular: factor of angular spring force.
- Linear: factor of angular spring force.
- Drag: simplified variance of factory Drag Force node. It slows down the effect.
Suggested caching procedure:
- Select third ICE tree, in post-simulation region, RMB and 'disable from here'
- Select point cloud, go to Animate>Plot>Write Geometry Cache
- - - Be sure to cache *only* point positions and point velocity - - -
- Duplicate and hide the point cloud
- Load cache on duplicated point cloud
- Enable all ICE trees on duplicated point cloud
Important parameters:
- Weight function curve: Modulates effect of rotation along strand length.
- Weight: global, per point weight of effect.
- Compensate Length : Gradually scales the strands when they are rotated, for correct bending.
- Do nothing First Frames: first frames of local simulation time, where node prevents unwanted effects, by blocking any effect of simulation.
- Simple Emitter Collision: It just prevents the strands to move 'on other side' of plane, defined by emitter's point normal. It's not accurate for long strands.
External geometry should be 'closed'.
Outputs Boolean value per 'chunk' (three guides at triangle
corners), or by point/hair root, in case of simple random
emission
- according to distance to external geometry.
Outputs Boolean value per 'chunk' (three guides at triangle corners), or by point/hair root, in case of simple random emission. Requires external geometry with closed volume.
Outputs relative distance to center of emitting triangle. It
has effect only in 'guides and filler' mode. In picture bellow, hair
length and hair color are modified by this node.
Procedure:
1: select NURBS surface, run 'NURBS to Mesh' from Model>Create>Poly.Mesh
2: In PPG, set: From Control Hull = ON, Stitch = OFF
3: Freeze the mesh
4: Create ICE tree on NURBS surface, apply the node
Important parameters:
ID:
- Point: ID is per point (hair root), effect is the same as with factory Randomize Value By Range.
- Chunk: ID is per triangle of guides. Has effect only in 'Guides and Filler' mode.
- Group: ID is per group of points, created by kH Grouping node. It has different effect only if kH Grouping is applied before.
Picture shows the effect kH Hair Length, modulated by kH Random Value in different modes.
Output is scalar per point.
Anto Matkovic
June 2012