Spore

Paintable particle node for scattering objects in Maya

Spore is a set of Maya plug-ins and scripts for Autodesk Maya. The Spore toolset is based on the sporeNode and sporeContext.

The sporeNode is a custom dependency graph node that produces an instanceData attribute which is designed to be hooked to Maya's particle instancer node.

The sporeContext is designed to place and manipulate points in the instanceData attribute.

Motivation

While particle instancing in Maya is a popular way to populate environments, the means of manipulating per-particle attributes are limited and require some specific knowledge.

Spore tries to create a more intuitive interface to creating and manipulating points that drive Maya's particles instancer. Spore allows to scatter, paint and modify points in an easy an intuitive way. Points can either be place with one of four different sampling algorithms or with an interactive brush context. Once points have been placed in the scene they can be interactively and effortless modified using one of four different "grooming" brushes.

Design

It is important to note that spore is probably not the right tool if you want to scatter massive environments. However, following some simple guidelines you can still achieve reasonable results.<br> Probably most important is to split up your environment in many different spore nodes. It is better to have lots of nodes with fewer points than having a single node with millions of points. This is because holding points is rather effortless for spore while modifying them, especially large amounts, is expensive. Once you have placed a certain amount of points, try to create a new node on the same target surface. The Spore Manager can help to streamline this particular workflow.

Installation

1. clone the git repo

git clone https://github.com/wiremas/spore

2. edit the spore.mod file to match the spore location on you machine:

spore any /path/to/spore/

3. finally copy the spore.mod file to a location your MAYA_MODULE_PATH environment variable points.
   Run the following mel command to find an appropriate location

getenv("MAYA_MODULE_PATH")

Dependencies

In order to run spore you need to have scipy and numpy installed.

• If you're running Linux or Mac just install using pip.
  
• If you're running Windows you should run...

pip install -i https://pypi.anaconda.org/carlkl/simple numpy
pip install -i https://pypi.anaconda.org/carlkl/simple scipy

... or try to follow this guide.

Usage

Load the spore plugin from Maya's plugin manager.

From the "Spore" menu select "Spore Manager" to open the ui.

sporeNode

The sporeNode takes an inMesh input attribute and creates an instanceData output attribute. The instanceData attribute is designed to drive a particle instancer. To specify a target mesh connect the target's shape outMesh attribute to the spore's inMesh attribute.

---

Instanced Objects

The Instanced Objects menu give quick acces to adding or removing objects to the instancer without the need to specifically select the instancer node. The list mirrors the list of source objects displayed in the instancer node.

In addition the list also acts as modifier for most of the brush and sample operations. Selecting one or more objects from the list will enable Exclusive Mode. In Exclusive Mode only the selected objects IDs are considered for the specified operation.

---

Instance Transforms

The Instance Transforms menu allows set transformations for instanced objects

Attribute
Align To	Define a target vector for rotation
Weight	Set weight of the target vector
Min Rotation	Minimum rotation values
Max Rotation	Maximum rotation values
Uniform Scale	Scale XYZ uniformly (X defines the uniform value)
Min Scale	Minimum scale values
Max Scale	Maximum scale values
Scale Factor	Factor for increasing/decreasing scale values
Randomize / Smooth	Factor for randomizing/smoothing scale values
Min Offset	Minimum offset along surface normal
Max Offset	Maximum offset along surface normal

---

Brush

The Brush menu exposes basic brush settings. For more detail on the individual brushes see sporeContext section.

Attribute
Tool	Set the brush context to the specified mode
Radius	Define the brush radius
Number Of Samples	Number of points created by a single brush tick
Min Distance	Minimum distance between each brush tick
Falloff	Define a falloff for the brush

---

Emit

The Emit menu controls settings used for the next sampling operation.

Attribute
Type	Set the sampling type
Number of Samples	Number of samples generated by the random sampler
Cell Size	Cell size for the jitter gird
Min Radius	Minimum radius for the 3d disk sampler
Min Radius 2d	Minimum radius for the 2d disk sampler

The sporeNode features four different sampling types:

1. random sampling
   Distribute points uniform randomly across the surface. Fast, but sampled points tend to clump together or form empty spots
   
   
2. jitter grid
   A uniform grid is created around an initial point cloud, generated by the random sampler. Than from each cell a random point is choose. This results in higher sampling times since some of the sampled points are discarded but the result looks slightly more pleasing.
   
   
3. 3d poisson disk sampling
   Generated poisson disk samples are at least the distance r apart from each other.
   This results in very pleasing result but takes a lot longer to sample. Note: be carefure with the minRadius attribute since small values increase computation
   http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.591.736&rep=rep1&type=pdf
   
   
4. 2d poisson disk sampling
   Generate poisson disk samples in uv space that are at least the distance r apart from each other.
   Note: be carefure with the minRadius attribute since small values increase computation
   Note: samples will only be generated in the uv space from 0 to 1. Therefore the radius can not exceed 1.
   http://www.cs.ubc.ca/~rbridson/docs/bridson-siggraph07-poissondisk.pdf
   
   

Geometry Cache

To accelerate sampling and other operations, target meshes will be cached in memory. These cache objects are shared between nodes. Meaning that even if you create multiple spore nodes for the same mesh, the cache has to be created only once. Depending on the size of the mesh, caching might take a few seconds.
To prevent a lot of computational overhead the cache will not update automatically when the mesh is transformed or deformed. In general, every time the cache is requested, it will evaluate if there have been any changes to the mesh. If this is the case it will automatically recache the mesh. Just note, that whenever you modify your mesh you add some extra computation to your operations.

There is also the option to force a recache in the Cache menu.

Filtering

Sampled points can be filtered using one of the following operations:

1. Texture Filter
   The texture filter removes points based on an the incoming shading network's red channel.
   Note: Texture filtering is based on sampling uv coordinates for corresponding points. Sampling uv values take a long time on high poly meshes!
   

   Attribute
   Use Texture	Enable texture filtering
   Texutre	Connect a shading network to evaluate

2. Altitude Filter
   Filters points based on hight relative to the targets bounding box.
   Use the fuzziness attribute to create a soft transition
   

   Attribute
   Min Altitude	Set lower filter bound
   Max Altitude	Set upper filter bound
   Min Altitude Fuzziness	Set lower bound fuzziness
   Max Altitude Fuzziness	Set upper bound fuzziness

3. Slope Filter
   Filters points based on the angle between the surfaced normal and the world up vector
   Use the fuzziness attribute to create a soft transition
   

   Attribute
   Min Slope	Minimal angle
   Max Slope	Maximal angle
   Slope Fuzziness	Set fuzziness

sporeContext

The sporeContext is an interactive brush tool that can manipulate the sporeNode's "instanceData" attributes. The context features seven different modes plus modifiers. Depending on the active context mode different brush controls are available directly on the sporeNode.

Modifier
b-click + drag	Modify brush radius

Undo / Redo

The sporeContext fully supports undo. Unfortunately, there is currently no way to redo operations.

Place Mode

Place a singe instance per brush tick

Modifier
Shift	Drag Mode
Meta	Align to stroke direction *

• the brush radius attribute also affects the way the stroke direction vector is generated. A larger brush radius will generate a more steady stroke at the cost of less precision.

Spray Mode

Place n instances per brush tick within the given radius

Modifier
Shift	Drag Mode
Meta	Align to stroke direction *

• the brush radius attribute also affects the way the stroke direction vector is generated. A larger brush radius will generate a more steady stroke at the cost of less precision.

Scale Mode

Scale all instance within the given radius

Modifier
Shift	Smooth
Meta	Randomize

Align Mode

Align all instances within the given radius to the specified axis

Modifier
Shift	Smooth (same as align to normal)
Meta	Randomize

Move Mode

Move all instances within the given radius along the stroke direction

Id Mode

Modify the objectIndex points within the radius to the specified ID. ID can be specified by enabeling Exclusive Mode. If the meta modifier key is pressed, n number of samples are randomly set to the specified objectIndex per brush ticks. Brush ticks can be modified using the Min Distance attribute

Modifier
Shift	---
Meta	Assign random

Delete Mode

Remove all instances within the given radius. If the meta modifier key is pressed, n number of samples are randomly deleted per brush ticks. Brush ticks can be modified using the Min Distance attribute. While the tool is active objects can be restored using the shift modifier key. Once you leave the context, it is no longer possible to restore objects.

Modifier
Shift	Restore (Works only until the context is left)
Meta	Delete random

Exclusive Mode

In Exclusive Mode the context works only on certain objectIndex IDs. To activate Exclusive Mode select the desired sources objects in the sporeNode's instance object list.

sporeCommand

The spore command can be used to create a new spore setup from Maya's script editor.

cmds.spore()

Spore Manager

The Spore Manager is a interface which lists all spore nodes in the scene.
It helps to quickly switch between different setups and display modes or create new spore nodes

Navigation
Control-click	Multi select
Right-click	Context menu
Double-click	Rename

Display modes
geometry	Set instancer LoD to geometry
bounding box	Set instancer LoD to bounding box
bounding boxes	Set instancer LoD to bounding boxes
solo	Solo the instancer connected to the specified spore node

Spore Reporter

The Spore Reporter helps to track issues and bugs or simply allows you to suggest a feature. When Report Bugs is enabled in the spore globals the Spore Reporter pops up whenever an unhandled error occurs. To send reports automatically enable Automatic Report in the spore globals.

The report tool wraps an onlineservice called anonymouse.org. Message delivery can take up to twelve hours.