Houdini Python Viewer States

Users can interact with Houdini in viewport through Python Viewer States in the following ways:

• Display handles

• Interact with geometry

• Display guide geometry

• Interact with state parameters

• Select geometry

• Display a custom right-click menu

• Interact using low-level UI events, like mouse, keyboard and tablet

• Wrap changes in undo blocks

• Run cross multiple context-levels

Interact using low-level UI events

UI Event Handlers

These are supported through ui_event, and they are:

• onMouseEvent

• onMouseDoubleClickEvent

• onMouseWheelEvent

• onKeyEvent

• onKeyTransitEvent

• onMenuAction

• onMenuPreOpen

• onParmChangeEvent

• onNodeChangeEvent

• onPlaybackChangeEvent

• onCommand

Typical ui_event received via callback function's kwargs :

ui_event {
	<class hou.ViewerEvent>,
		'point': hou.Vector3(2.52767920,2.22849488,5.74832201),
		'dir': hou.Vector3(-0.63586962,0.45803502,-0.62118733),
		'hasQueuedEvents' :0, 
		'queuedEvents' : 0, 
		'value' :[0, 1524, ], 
		'reason' : hou.uiEventReason.Located, 
		'valueType' : hou.uiEventValueType.FloatArray,
		'device': {
			<class hou.UIEventDevice>,
				'isAltKey' : 0, 
				'isAutoRepeat' : 0, 
				'isKeyPressed' : 0, 
				'isKeyDown' : 0, 
				'isKeyUp' : 0,
				'isCapsLock' : 0, 
				'isCtrlKey' : 0, 
				'isKeyPad' : 0, 
				'isShiftKey' : 0, 
				'isFunctionKey' : 0,
				'isArrowDown' : 0, 
				'isArrowLeft' : 0, 
				'isArrowRight' : 0, 
				'isArrowUp' : 0, 
				'isLeftButton' : 0,
				'isMiddleButton' : 0, 
				'isRightButton' : 0, 
				'keyString' : '', 
				'keyValue' : 0, 
				'modifierString' : '',
				'mouseWheel' : 16.84, 
				'mouseX' : 0, 
				'mouseY' : 1524, 
				'isTablet' : 0, 
				'tabletAngle' : 0,
				'tabletPressure' : 1, 
				'tabletRoll' : 0, 
				'tabletTilt' : 90, 
				'time' : 573.8
		}
}

Lifecycle Event Handlers

• onEnter

• onInterrupt

• onExit

• onResume

• onGenerate

Handle Event Handlers

• onHandleToState

• onStateToHandle

• onBeginHandleToState

• onEndHandleToState

Selection Event Handlers

• onStartSelection

• onSelection

• onStopSelection

• onLocateSelection

Drag & Drop Event Handlers

• onDragTest

• onDropGetOptions

• onDropAccept

Drawing Event Handlers

• onDraw

• onDrawInterrupt