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Leaf Mesh Generator

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The Leaf Mesh generator is responsible for generating leaves based on materials and mesh assets. Leaf Mesh generators (along with Batched Leaf generators) are the primary mechanism by which season transitions occur.

Generation

The properties in this group control how many leaves are generated and where they are placed.

Forces

The properties in this group control how forces affect the nodes created by this generator. Forces affect only the orientation, not the position, of leaf meshes.

Allow Forces

When enabled, all forces that are checked will act on the generator.

Forces

Each force in the scene has an entry here. Check the box next to the name to enable the force for this generator. The value set here is multiplied by the strength of the force before being applied to the branch. The profile curve controls have no effect on leaves.

Note: Click on the force name to edit the force's properties.

Random Seeds

Properties that have variance are given random values based on a seed value in this group. Vary the seeds in this group to randomize only the properties associated with the seed type.

Randomize All

Randomizes the value for all seeds used to compute this generator.

Leaves

The properties in this group control the type, size, and initial placement of the leaf nodes.

Size

This property sets the size of the leaf nodes. By default, mesh assets are treated as unit meshes and then scaled by this amount when placed on the model.

Use Actual Size

When enabled, the size parameter is ignored and the mesh is used at exactly the size at which it was modeled.

Flip

When enabled, randomly selected leaf nodes are flipped over the Y axis.

Weld

When enabled, leaves will be placed directly on the skin of their parent (as opposed to being anchored on their spine).

Cross

When enabled, leaves are rotated so that they are perpendicular to the original leaf placement. This is a short cut for creating crossed, intersecting meshes that have the same position.

Fix Einding

When enabled, the face winding of the polygons in the final mesh is adjusted to match the direction of the surface normals. This correction is applied after vertex deformation and lighting adjustments.

Type

The properties in this group specify the materials and meshes for the leaf. Meshes must be assigned to the material on the Material Bar to be used on the leaf. Materials are chosen based on their weights and season settings.

Material

This property specifies a named material from the Material Bar. If “None” is selected or the chosen material has no assigned mesh, a simple square will be used as placeholder geometry.

Weight

Sets probability that a node will receive this material (this weight ÷ sum of all weights).

Resolution

The properties in this group influence the resolution of the mesh.

Size Increase %

This curve controls the increase in size of the leaf nodes as the resolution changes. It is often desirable to increase the size of the leaves at lower resolutions to make up for a lower number of leaves.

Mesh LOD

This curve sets which mesh version (“High”, “Medium” or “Low” detail on the mesh asset) is used based on the active resolution.

Mesh LOD Offset

When set to a value other than 0, the mesh currently assigned will go up or down in mesh resolution (“High”, “Medium” or “Low” detail on the mesh asset). Use this property (especially in conjunction with its parent curve) to adjust mesh resolution throughout the model.

Note: “Mesh LOD” and “Mesh LOD Offset” both require meshes assigned in at least two of the three mesh asset LOD slots.

Local Orientation

The properties in this group are the first stage of orienting the leaf. The orientation actions are performed in the order in which the properties are listed.

Unification

Uses the anchor to orient itself “out” before the rest of the orientation adjustments are performed. The “Out” direction is considered to be the vector from the anchor point through the node's attachment point. Anchor point placement options are as follows:

GlobalThe anchor point is located where the node's highest ancestor hits the ground.
DeepThe anchor point is the base of a node very near (and sometimes exactly on) the root of the node's ancestors.
IntermediateThe anchor point is somewhere in the middle of the node's ancestors.
LocalThe anchor point is very near where the node is attached.
NoneNo anchor point is computed, and no unification is done.
Sky Influence

Controls how much the leaves point toward the sky. Higher numbers result in the 'Z' axis of each mesh pointing straight up.

Fold

Rotates leaves up or down around the parent's growth direction.

Align

Rotates the tip of the leaves toward or away from the parent's growth direction. Use this property to point leaves in the direction the parent is growing.

Face

Spins leaves around their stem so that their “up” vector points in the direction of the parent's growth. Use this property to make the leaves face out relative to their parent.

Note: Interval and Phyllotaxy generation modes work best with these properties. These modes give each leaf an idea of which side they're on. Doing so makes a positive value for “Align,” “Face,” and “Fold” all work the same, regardless where the leaf was generated.

Sensitivity

The properties in this group control the second stage of leaf orientation.

Parent

Parent sensitivity refers to orienting the leaf based on where it is positioned relative to its ancestors.

Amount

Sets the amount that the bottom of the leaf is turned to face the point set by Anchor.

Anchor

This property picks a spot on one of the leaf's ancestors according to the following options:

GlobalThe anchor point is located where the node's highest ancestor hits the ground.
DeepThe anchor point is the base of a node very near (and sometimes exactly on) the root of the node's ancestors.
IntermediateThe anchor point is somewhere in the middle of the node's ancestors.
LocalThe anchor point is very near where the node is attached.
NoneNo anchor point is computed, and no parent sensitivity is added.
Sky

Rotates the mesh around its central axis to get its “Z” axis as close to up as it can. Think of it as the leaves rotating around their stem to face the light.

Final Adjustments

These edits are applied to the leaf meshes as a group, after Local Orientation and Sensitivity are computed.

Up

Rotates each mesh around its local X axis.

Rotates each mesh around its local Y axis.

Out

Rotates each mesh around its local Z axis.

Deformation

The properties in this group alter the shape of the the leaf mesh. It is important to remember that these properties work best when there are enough vertices in the mesh to reveal the changes.

Note: Using these properties on low resolution meshes can produce undesirable results. You should always have at least one vertex near the center of the mesh for the best results.
Fold

Folds both sides of the leaf, length wise, along the Y axis of the mesh. A negative value bends down, while a positive value bends up.

Curl

Curls the leaf around the mesh's X axis.

Twist

Twists the leaf around the mesh's Y axis. The farther away a vertex is from the X axis, the more it is rotated.

Vertex

The properties in this group perform a noise-based deformation of each vertex in the mesh.

Amount

This property controls the amount of noise applied to each vertex.

Noise

This value controls the tightness of the noise pattern. Higher values result in more localized deformations.

Seed

Vary this parameter to randomize the noise pattern.

Scale

The properties in this group scale the mesh. The scale is performed in each leaf's local orientation.

X

Scales the mesh by this amount in the X axis.

Y

Scales the mesh by this amount in the Y axis.

Z

Scales the mesh by this amount in the Z axis.

Lighting

The properties in this group modify the vertex normals to change the lighting behavior of the mesh.

Note: These properties are not typically necessary for high detail VFX models but they can significantly improve the lighting on meshes that represent clusters of leaves in real-time models.

Parent Puffiness

Amount

Value scale that controls how much the normals on each individual leaf should face “out” depending on the assigned anchor point. A value of 1.0 makes each normal line up with the vector that goes from the anchor through the vertex.

Note: Click on a leaf with hints on to see the “Parent puffiness” vectors.
Anchor

This property picks a spot on one of the leaf's ancestors according to the following options:

GlobalThe anchor point is located where the node's highest ancestor hits the ground.
DeepThe anchor point is the base of a node very near (and sometimes exactly on) the root of the node's ancestors.
IntermediateThe anchor point is somewhere in the middle of the node's ancestors.
LocalThe anchor point is very near where the node is attached.
NoneNo anchor point is computed, and no parent puffiness is added.
Puffiness

After all normal adjustments have been performed, this value “sphere-izes” the normals around the center of the mesh, making the geometry have a more puffy appearance.

Unify

This property causes all vertex normals to point in the average direction of all of the vertex normals. Use this property to align the normals to help localize specular effects.

Adjustments

The properties in this group rotate the normals of each leaf without rotating the geometry. These properties are commonly used when creating clusters.

Hint: Apply variance to these properties to make leaves in a cluster appear jumbled when lit in the final model.
Up

This property rotates vertex normals around the local X axis.

Right

This property rotates vertex normals around the local Y axis.

Out

This property rotates vertex normals around the local Z axis.

Wind

The properties in this group influence how leaves are animated in wind simulations.

Scalar

Use this property to scale how much the leaf moves during wind simulations. The amount and frequency of motion is set on the Fan object. The left hand side of the profile curve corresponds to the pivot point. The right hand side corresponds to the vertex farthest away.

Note: The left hand side of the profile curve must be zero to avoid disconnections from parent.
Group

In many wind styles, multiple wind groups are available. Use this property to specify which group the leaves belong to. The most common use of this feature is to have separate animation parameters for leaves and fruit.

Seed

Vary this parameter to randomize wind characteristics.

Growth

The properties in this group govern the growth behavior of the leaves.

Note: Leaf growth is still under development.

Season

The properties in this group control how leaves transition in the seasons system.

Start Offset

Leaf transitions are determined by looking up season curves based on the position of the season slider. This value provides an offset on that curve lookup. Use variance on this property to randomly shift when neighboring leaves begin their transition.

Time Scale

Scales how fast time passes relative to a single leaf. Higher values make leaves transition faster.

Drop Time

Controls how long the leaf will remain attached. A leaf can drop no matter what material is assigned.

Droop

Use this value to make leaves droop as they transition.

Curl

Use this value to make leaves curl as they transition.

Fold

Use this value to make leaves fold as they transition.

Fallen

When “Show dropped leaves” is checked on the Season Slider, the properties in this group influence the behavior of leaves on the ground (or ground mesh).

Ground duration

The amount of time the leaves stay on the ground before disappearing.

Spread

Controls how far from the point directly under the tree the leaf may travel before hitting the ground.

Flatten

Determines the amount of deformation removal (“Season:Curl” and “Season:Fold”) applied to the fallen leaves.

Jumble

Randomizes the orientations of leaves on the ground.

Slope Limit

If you have a force mesh applied to the leaf generator, fallen leaves will adhere to it instead of the ground. In that circumstance, use this property to keep leaves from gathering on slopes.

Dynamic LOD

The properties in this group control the LOD behavior of the leaves.

Weight

Use this value to increase or decrease the likelihood that leaves in this generator will survive the LOD process (vs. leaves in other generators). Use the parent curve to target specific areas of the model.

Scale Factor

Leaves that survive the LOD process grow to fill the vacated space. The amount is set in the Tree generator's LOD section. This property scales that amount for leaves in this generator.

Mesh Index

This curve controls which mesh LOD (if present) is used for each LOD state. The left side of the curve corresponds to the highest LOD. The right side corresponds to the lowest LOD.

Vertex Color

The properties in this group control how vertex colors are computed.

Note: “Vertex colors” must be enabled on the Tree generator for these properties to work.

Red

The properties in this group control how the red component of the color is computed.

Style

This property controls how the red portion of the color is computed from the following options:

Set Sets the color directly using the “Value” property (parent colors are ignored).
Offset from parent The “Value” property is added to the the vertex color inherited from the parent.
Value

This property adds to, subtracts from, or directly sets this color component.

Green

The properties in this group control how the red component of the color is computed.

Style

This property controls how the red portion of the color is computed from the following options:

Set Sets the color directly using the “Value” property (parent colors are ignored).
Offset from parent The “Value” property is added to the the vertex color inherited from the parent.
Value

This property adds to, subtracts from, or directly sets this color component.

Blue

The properties in this group control how the red component of the color is computed.

Style

This property controls how the red portion of the color is computed from the following options:

Set Sets the color directly using the “Value” property (parent colors are ignored).
Offset from parent The “Value” property is added to the the vertex color inherited from the parent.
Value

This property adds to, subtracts from, or directly sets this color component.

Mesh Asset

The properties in this group control how vertex colors stored in the mesh asset are combined with the computed vertex colors.

Style

This property controls how mesh asset vertex colors are used from the following options:

Interpolate The “Contribution” value is used to blend from the computed to color (0.0) to the color stored in the asset (1.0).
Add The “Contribution” value is used to scale the mesh asset vertex color and the result is added to the computed vertex color.
Contribution

This value sets how much influence the mesh asset vertex color has on the final vertex color.

Collision

The properties in this group influence how leaves in this generator interact with the collision system.

Style

Use this property to set how the leaves behave during collision computations from the the following options:

Everything Leaves in this generator collide with each other and all other leaves.
Ignore Siblings Leaves in this generator ignore siblings but collide with everything else.
Knock out Others Only Leaves in this generator cannot be removed, but they can eliminate leaves in other generators.
Nothing These leaves do not participate in collision computations.
Take Parent

When enabled, if a leaf in this generator is removed, its parent is also removed. Use this option to take away twigs supporting leaves that are removed.

Weight

When leaves collide, the one with the higher weight wins. Use this property to set the weight.

Pivot Threshold

This property sets how far away from pivot (as a percentage of size) a collision has to happen in order to count. Use this property to eliminate unwanted removals of leaves anchored near each other.

Sphere Threshold

When using spherical leaf collision tests, this value scales the size of the spheres used during the test. Spheres are initially sized based on leaf size.

Lightmap

The property in this group affects the influence leaves in this generator have on the lightmap.

Note: Not all versions of the Modeler support lightmap UV computation.
Weight

Use this property to increase or decrease the importance of this generator's leaves in the lightmap – in relation to the lightmap weight of all other objects – before lightmap packing is determined. Note that your Weight value may not be honored exactly or may get so large as to exhibit unexpected results. Use “Tools→Reset lightmap scalars” to go back to default values for the whole model.