Select Sub-mesh

The sub-mesh selection box allows the user to select the different authorable clothing sub-meshes. We recommend using different sub-meshes for different clothing areas to be simulated, e.g. a cape, hair, skirt, jacket, etc.

Each line corresponds to a meshname/materialname pair. Multiple ones may be selected to create one single Clothing Asset from.

Sub-mesh Subdivision

The Clothing tool allows the user to subdivide a graphics mesh further through the ‘Modifications’ interface. Since the clothing physics mesh is generated based on the graphics mesh, subdividing the graphics mesh results in a higher tessellated physics mesh.

If the physics mesh tessellation is pretty high, it is recommended using the ‘Hard Stretch Limitation’ feature provided in the Clothing Material library

Culling

This is used to tell the tool and APEX how to cull a specific mesh. It applies for the entire mesh, and not just for a sub-mesh.

This information will be stored in the asset and given out through the Render API.

Histogram and multiple physics meshes

This will generate a multitude of physical meshes each a subset of all triangles. Additional meshes will have a smaller subset, containing only vertices of high max distance.

The additional physics meshes allow the APEX run time to switch between the different physics meshes when the allocated resources for clothing simulation are exceeded.

Each blue line in the Histogram will generate an additional physical mesh, based on the subset of vertices that have a max distance greater or equal to the blue line.

Histogram and painted Max Distance values	Physical LoD visualization

Lod 1	Lod 2	Lod 3

Automatic Generation

Each bone can have 3 different options for automatic geometry generation:

The default value for every bone is ‘Include’. However if the bone name contains either ‘finger’ or ‘toe’ the default will be ‘Exclude’.

Each bone can either have a Convex or a Capsule collision volume.

• The convex collision volume is generated by computing the convex hull from all the vertices gathered for a certain bone.
• The capsule collision volume is generated by computing the best fit capsule for the gathered points.

The <Minimal Weight> value can be changed per bone which will trigger an auto update for that particular bone.

If at any state the auto update seems to produce wrong results, the ‘Build Collision’ button can be pressed for full regeneration.

Inflation

After automatic generation, each collision volume can be inflated (or deflated). For capsules this will just modify the radius, for convexes it will move their vertices.

Manual generation

When selecting a single bone, the collision volumes can be altered or even fully regenerated for that bone. Additional volumes can be added, and they can be moved and rotated as well as changed in size.

Static Parameters

• Thickness

  Each Cloth Vertex will be simulated as a sphere with half this thickness as the radius. This allows the cloth vertex to keep a minimum distance off from any collision volume.

• Self-collision Thickness

  When turning on self collision (see Flags section) each particle will be represented as a sphere. Colliding with other spheres will be more likely if they are bigger.

  As usual the rule is. Keep them as small as possible, but as big as needed.

• Hierarchical Levels

  Number of hierarchical edges the Cloth will create. This is only applicable if the number of hierarchical solver iterations in the Clothing Material is set to larger than 0.

  Note

  Use with care. This will increase the cooking time significantly, use more memory and more CPU at run time. Hard Stretch Limitation might be a better alternative to try first.

Flags

• Disable CCD

  Never use Continuous Collision Detection. Setting this is not recommended. The ClothingActor will take care when to use and not use this flag upon teleportation or similar situations where continuous collision is not desired.

• Two-way Interaction

  Enables two-way coupling of clothing and dynamic rigid bodies. This is usually not necessary since regular clothing has very limited influence on most dynamic objects.

• Self-collision

  Turn on self collision. See also Self Collision Thickness.

  Note

  This comes with some severe performance implications!

• Untangling

  If self-collision could not prevent the cloth from entangling with itself

  Note

  This comes with big performance implications, use with absolute care!

Material Libraries

This list box presents the list of all currently loaded clothing materials. Select one to display its list of materials in the next window.

Using the [+] and [-] buttons more material libraries can be added or released.

Materials

Display the list of Materials inside a Material Library. Select one to watch all the settings.

Using [+] and [-] buttons more materials can be added to or removed from the library. The [Select] button will select the current combination of library and material for the next clothing asset that is created.

Clothing material

A series of elements presenting all the contents of a clothing material

Use Input Mesh

• Subdivide

  Subdivide the clothing mesh right after import from the graphical mesh.

  Only needed when the graphical mesh has ill-shaped triangles or is tessellated very irregularly.

• Close Mesh

  If the graphical mesh has holes, they will be closed in the physical mesh.

• Displacement

  Move each physical vertex along its normal.

• Derive Normals from bones

  Instead of copying normals from the graphical mesh, the bone hierarchy is consulted and the normal is pointing away from the bones.

• Generate

  Will actually create the clothing physical mesh according to these parameters.

Modify Cloth Mesh

• Simplify

  Simplifies the clothing mesh up to a certain edge length.

• Simplification Step

  Removes around 10% of the edges with each subsequent click.

Save/Run

• Save Asset

  Writes the clothing asset into a stream (either .aca or .xml/.ini/.abi files).

• Transmit to External Application

  Some Game Engines such as Unreal Engine 3 support direct transmission to the Editor instead of going through the file system.

• Start Simulation

  Generate one or more actors from the clothing asset and simulate it.

Step 1) Create an Iso Surface

• The Grid Resolution

  The bounding box of the mesh will be filled with grid cells. The edge length of such a grid cell is the bounding box diagonal divided by the <Grid Resolution>

• Keep all/some meshes

  There can be multiple disjointed iso meshes. The most frequent case is the inner and outer mesh, usually when the original mesh is closed. This allows to select how many meshes to keep. The meshes with a higher vertex count will be kept longest.

• Derive Normals From Bones

  Instead of using the mesh normals from import, normals are computed as the direction pointing away from the bone with the largest weight.

• Create

  Actually create the iso surface according to the parameters.

Step 2) Simplify the Iso Surface

• Simplify <Number>

  Simplify all edges that are shorter than the bounding box diagonal divided by the selected <Number>

• Simplify Step

  Each time this button is pressed it will simplify roughly 10% of all the edges.

Step 3) Tetrahedralize

This will fill the iso meshes with tetrahedrons.

Step 4) Start Simulation

• Alternatively the Asset can be saved or transmitted, identical as for Single Layered Clothing.

Actions

• Restart

  Restarts the simulation, all ClothingActors are released and recreated immediately.

• PVD

  Initiates a PVD connection

Info

• Size

  The size of the bounding box

• Scene scale

  Reference scale which scales most scene parameters such as Gravity, painting, debug rendering etc.

Actor Count

• The slider allows to create up to 25 ClothingActors that will be independently simulated. Animation will be synchronous.

• Use Preview Instead

  Creates ClothingPreview classes instead of ClothingActors. This will allow only to animate the Clothing Asset, but not to simulate. Good comparison to what it would look like without clothing.

PhysX run time Parameters

• Sim Frequency

  Quickly change the Simulation Delta (which is 1 / simFrequency). Use with care, 50Hz and above are recommended. It is not very useful below 30Hz.

• Gravity

  Quickly play with various gravity values. The range is from 0.1 * ‘Scene Scale’ to 2 * ‘Scene Scale’

• GPU Cloth Sim

  Run the Cloth simulation on the GPU (CUDA capable GPU is required). Should not affect behavior, but performance will differ.

• Sequential Primary (Compartment Fix)

  Allows to run the Clothing Compartment before the Rigid Body Compartment. Can lead to more stable simulation, but doesn’t make a difference in most cases.

• Enable Wind

  Show/Hide Wind window

  

  • Direction

    Rotate wind origin around the up axis

  • Elevation

    Blow from above or below

  • Velocity

    Modify strength of the wind

• Groundplane

  Moves the ground plane up and down

APEX run time Parameters

• Graphical Lod

  If available, select which graphical LoD is taken

• Budget

  Reduce the available simulation units. Useful to see how load balancing will work on multiple Actors.

• Lod Overwrite

  Force select which physical LoD is used.

• Blend Time

  Modify the Time it takes to blend from maximum physical LoD to no simulation at all.

• Animation uses global poses

  If Bind Poses are not identical in the Clothing Asset and the FBX file providing the animation, this is a workaround.

• Modify Actor Material

  Pop up a window that allows to modify the current material, or to set a new one per ClothingActor.

  A ClothingActor needs to be selected by clicking it.

Animation

• Time

  The length of the animation

• Start/Stop Animation

• Speed

  Select how fast the Animation is played back

• Select Animation

  Usually this offers to chose between the Bind Pose or the animation

• Move Camera with animation

  Lock the camera motion to the root bone motion.

• Loop Animation

  Jump back to 0 at the end of the animation and keep playing

• Lock root bone

  Overwrite the root bone translation to Zero all the time

• Animation is continuous

  Do set the isContinuous flag even when the animation loops back to zero

Graphical Mesh

Render graphical mesh textured, solid, wireframe or not at all

Painting

• Painting Visible (Faces)

  Render the painting on the edges of the mesh

• Painting Visible (Vertices)

  Draw Lines along the normal of each vertex displaying the paint value

• Painting, show other sub-meshes

  Display all sub-meshes that are not selected for clothing

Cloth Mesh

Draw the Cloth mesh solid, wireframe or not at all.

Collision

Draw collision volumes solid, wireframe or not at all.

Iso Mesh

Draw Iso Mesh solid, wireframe or not at all.

Tetras

Draw Tetra Meshes solid, wireframe or not at all.

Misc

Render the Skeleton as presented by the imported mesh

Clipping

Clip some of the intermediate meshes.

Animation

Display the animation as loaded from the importer

Original Mesh

Render the imported mesh textured, solid, wireframe or not at all

Apex Mesh

Render the simulated mesh textured, solid, wireframe or not at all

SDK Visualization

• Collision Shapes

  Wireframe render collision volumes from PhysX

• Clothing Mesh Solid:

  Render Simulation Mesh solid

• Clothing Mesh Wire

  Render Simulation Mesh wireframe

• Clothing Collisions

  Blue arrows for each Cloth vertex that collides with collision volumes.

• Hard Stretch Limit Graph

  Orange lines showing which edges have hard stretch limitation

APEX PhysX Mesh

• Skinned Positions

  Skinned positions of the physical mesh according to animation

• Physical Vertex Bones

  Shows the mapping between physical mesh vertices and the bones they skin to. White means a bone weight of 1.0, black a bone weight of 0.0

• Vertex Velocities

  Blue lines visualizing vertex velocities on the simulated mesh

• All Implicit Tetrahedrons

  Draws all implicit tetrahedrons for the entire physical mesh

• Bad Implicit Tetrahedrons

  Draws all tetrahedrons that have a graphical vertex mapped to them with barycentric coordinates outside the tetrahedrons.

• Skin Implicit Tetrahedrons

  Draws all tetrahedrons that are being used by the current mix of Mesh-Mesh Skinning and immediate skinning

APEX PhysX Max Distance

• Backstop Collision

  Visualize a subset of the simulation mesh where Backstop collision will occur. Red is outside, blue is inside.

• Backstop Umbrellas

  Visualize a small segment of the Backstop sphere at the current vertex location.

• Max Distance Outwards

  Display a line along the vertex normal that represents the radius of the Max Distance sphere.

• Max Distance Inwards

  Display a line along the negative vertex normal that represents the radius of the Max Distance sphere.

APEX Skeleton

• Skeleton

  Draw the subset of skeleton bones that are active in this APEX Asset (active bones are referenced by any of the meshes or have a collision volume)

• Bone Frames

  Draw the bone axis for each active bone

• Bone Names

  Draw the bone names for each active bone

APEX Graphical Mesh

• Render Normals

  Draw blue lines for each vertex displaying its computed normal.

• Render Tangents

  Draw red and green lines for each vertex displaying its computed tangent and bi-normal/bi-tangent.

• Graphical Vertex Bones

  The mapping from graphical vertices to bones. white line indicate a weight of 1, black lines a weight of 0.

ClothingActorFlags

• Parallel PhysX Mesh Skinning

  Skinning of the physics mesh will be done during simulation instead of before.

  Note

  This will cause one frame delay.

• Parallel Mesh Mesh Skinning

  Skinning of the graphical mesh according to simulation is done during the next time step.

  Note

  This will cause one frame delay.

• Parallel CPU Skinning

  All vertices with Max Distance 0.0 will be skinned regularly. This can and should be done during simulation already, so it should always be on.

• Recompute Normals

  Fully recompute the normals after all types of skinning have been done. This will replace the normals that were partly approximated or skinned with freshly computed ones. Some overhead but more quality.

Shaders

• Default

  Use a shader with per-pixel lighting.

• APEX Subdivision

  [experimental] Subidive the output mesh. A geometry shader will subdivide each triangle into 4 triangles and compute normals for the 3 new vertices. This can remove some artifacts with lighting, but also add new artifacts.

Misc

• Vsync

  Wait for screen refresh