====== Shortcut ======

^ viewport ^^
| W | toggle wireframe display |


====== Intro to Houdini ======

  * Houdini, a procedure oriented 2D,3D graphic application, with built-in package for a lot of simulation operation.


**Concept inside Houdini**

  * it is all about asset, anything is a asset, (tool, shelf, node, parameter)

^ OTL || Operator Type Libraries |
| | hda | houdini digital asset, file format for asset library which contain lots of assets (Channel Editor, Motion View) |
| IDO || Internally Defined Operator, built node asset type in houdini |
| | Chop | (#vop) channel operation, basically a attribute driving network of nodes |
| | ChopNet |
| | Cop2 |
| | CopNet |
| | Dop |
| | Driver |
| | Object |
| | Particle |
| | Pop |
| | Shop |
| | Sop |
| | Vop |
| | VopNet |
^ VEX builder operatpr |
====== Setting and Configuration ======

  * env file for environment setting <code>
HOUDINI_PATH = "$HOUDINI_PATH;X:/myPath/houdini/HFS/16;&"
HOUDINI_OTLSCAN_PATH = "$HOUDINI_OTLSCAN_PATH;X:/myPath/houdini/HDA_Libs/otls;&"
HOUDINI_TOOLBAR_PATH="$HOUDINI_TOOLBAR_PATH;X:/myPath/houdini/ToolBar/16;&"
</code>
  * icon path <code>
icon format: svg or PNG_20x20_pixel
custom icon should be in: HOUDINI_UI_ICON_PATH
  * $HOME/houdiniX.Y/config/Icons
  * $HOME/Library/Preferences/houdini/X.Y/config/Icons

system icon is at
houdini_19_app_path\houdini\config\Icons\icons.zip
houdini_18_app_path\houdini\help\icons.zip
</code>
  * start houdini with init script (optionally in full path)<code>
houdinifx.exe X:\myPath\123.py
</code>
  * houdini start will run 123.py, new session will run 456.py, it will always run pythonrc.py in its search path.
  * houdini python path environment variable "HOUDINI_PATH"

  * Houdini project env variables

^ $HFS/houdini, $HH | houdini environment |
^ $HSITE | store shared houdini resource |
^ $JOB | current work job directory |
^ $HIP | readonly houdini internal scene variable, last saved path |

  * list all configuration of houdini in Shell: <code python>hconfig -ap</code>
====== Tutorial ======

  * Rohan Dalvi on Vimeo: http://vimeo.com/rohandalvi
  * Go Procedure on Vimeo: http://vimeo.com/goprocedural/channels
  * PQ Houdini Tutorial on Vimeo: http://vimeo.com/channels/54102
  * Flexible Muscle-Based Locomotion: http://vimeo.com/channels/proceduralism/79098420

====== Houdini GUI Tool Develop ======

  * PySide/PyQt Custom GUI sample:
    * http://www.sidefx.com/ja/docs/houdini14.0/hom/cookbook/qt/
  * HOM: Houdini Object Model API reference for data access in Houdini
    * http://www.sidefx.com/ja/docs/houdini14.0/hom/cookbook/

===== Concept of Node under root hou =====

  * Houdini is same node concept as Nuke when access objects in application, based on a root node "hou" to access object under it, 
  * in Maya.cmds, you are calling Maya to return the data of the object by object string name instead of the object itself
    * while OpenMaya api and PyMel in Maya is more like same node concept

====== Houdini Digital Assets - HDA ======

  * houdini digital asset is like a group of node functions and saved as a big single node, like Gizmo in nuke.
    * doc ref: https://www.sidefx.com/docs/houdini/assets/namespaces.html
    * Make Your Own Houdini HDAs: https://www.youtube.com/watch?v=0uCrncu6_cY
  * HDA naming convention, (asset's internal name)
    * operator name: [namespace::]node_name[::version]
    * operator name with sub category: [namespace::]node_category/node_name[::version]
    * operate label: Node Name (as shown in menu)
  * HDA appearance in menu category:
    * HDA asset's Type Properties panel > Interactive tab > Shelf Tools tab > Context tab > Tab submenu path: BigFolder/SubFolderLike
      * also optionally to check OBJ, SOP, DOP alike content type filter
  * show HDA path info in panel
    * Window > Asset Manager : Configuration tab > asset definition toolbar = show always