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  3. UCurveControlPointsMechanic

UCurveControlPointsMechanic

A mechanic for displaying a sequence of control points and moving them about.

Unreal Engine C++ API Reference > Plugins > ModelingComponents > Mechanics

Inheritance Hierarchy

References

   
Module ModelingComponents
Header /Engine/Plugins/Runtime/MeshModelingToolset/Source/ModelingComponents/Public/Mechanics/CurveControlPointsMechanic.h
Include #include "Mechanics/CurveControlPointsMechanic.h"

Syntax

UCLASS ()  
class UCurveControlPointsMechanic :  
    public UInteractionMechanic ,  
    public IClickBehaviorTarget ,  
    public IHoverBehaviorTarget

Remarks

A mechanic for displaying a sequence of control points and moving them about. Has an interactive initialization mode for first setting the points.

When editing, hold shift to select multiple points. Hold Ctrl to add an extra point along an edge. To add points to either end of the sequence, first select either the first or last point and then hold Ctrl. Backspace deletes currently selected points. In edit mode, holding Shift generally toggles the snapping behavior (makes it opposite of the current SnappingEnabled setting), though this is not yet implemented while the gizmo is being dragged.

TODO:

  • Make it possible to open/close loop in edit mode
  • Improve display of occluded control points (checkerboard the material)
  • Allow deselection of vertices by clicking away?
  • Lump the point/line set components into PreviewGeometryActor.

Variables

  Type Name Description
Protected variable bool bAddToSelectionToggle Support for Shift and Ctrl toggles.
Protected variable bool bAutoRevertToInteractiveInitialization  
Protected variable bool bGizmoBeingDragged Used to make it easy to tell whether the gizmo was moved by the user or by undo/redo or some other change that we shoulnd't respond to.
Protected variable bool bInsertPointToggle  
Protected variable bool bInteractiveInitializationMode  
Protected variable bool bIsLoop  
Protected variable bool bSnappingEnabled  
Protected variable bool bSnapToggle  
Protected variable FViewCameraState CameraState Support for hovering.
Public variable UProperty TObjectPtr< USingleClickInputBehavior > ClickBehavior Behaviors used for moving points around and hovering them.
Protected variable FOrderedPoints ControlPoints This actually stores the sequence of point IDs, and their coordinates.
Protected variable int32 CtrlModifierId  
Protected variable int32 CurrentChangeStamp Used for expiring undo/redo changes, which compare this to their stored value and expire themselves if they do not match.
Protected variable FColor CurrentPointsColor  
Protected variable FColor CurrentSegmentsColor  
Protected variable float DepthBias  
Protected variable UProperty TObjectPtr< UPointSetComponent > DrawnControlPoints  
Protected variable UProperty TObjectPtr< ULineSetComponent > DrawnControlSegments  
Protected variable UE::Geometry::FFrame3d DrawPlane Used for adding new points on the ends and for limiting point movement.
Protected variable int32 EndpointSnapPriority  
Protected variable int32 FirstPointSnapID Used for snapping to the start/end of the curve to get out of initialization mode.
Protected variable UE::Geometry::FGeometrySet3 GeometrySet Used for spatial queries.
Protected variable TFunction< bool(const FVector3d &, const FVector3d &)> GeometrySetToleranceTest  
Protected variable FVector GizmoStartPosition The starting point of the gizmo is needed to determine the offset by which to move the points.
Protected variable FColor HighlightColor  
Public variable UProperty TObjectPtr< UMouseHoverBehavior > HoverBehavior  
Protected variable FColor HoverColor  
Protected variable int32 HoveredPointID  
Protected variable FColor InitializationCurveColor Variables for drawing.
Protected variable int32 LastPointSnapID  
Protected variable int32 LineSnapIDMin When storing user-defined lines to snap to, we add this to the user-provided id to avoid conflicting with any lines generated by the snap engine.
Protected variable int32 LineSnapPriority  
Protected variable int32 MinPointsForLoop  
Protected variable int32 MinPointsForNonLoop  
Protected variable FColor NormalCurveColor  
Public variable OnModeChangedEvent OnModeChanged  
Public variable OnPointsChangedEvent OnPointsChanged  
Protected variable float PointsSize  
Protected variable UProperty TObjectPtr< UCombinedTransformGizmo > PointTransformGizmo  
Protected variable UProperty TObjectPtr< UTransformProxy > PointTransformProxy Support for gizmo.
Protected variable FColor PreHoverPointColor Used to unhover a point, since this will differ depending on whether the point is selected.
Protected variable FColor PreviewColor  
Protected variable UProperty TObjectPtr< APreviewGeometryActor > PreviewGeometryActor Used for displaying points/segments
Protected variable UProperty TObjectPtr< UPointSetComponent > PreviewPoint These get drawn separately because the other components have to be 1:1 with the control points structure, which would make it complicated to keep track of special id's.
Protected variable UProperty TObjectPtr< ULineSetComponent > PreviewSegment  
Protected variable float SegmentsThickness  
Protected variable FColor SelectedColor  
Protected variable TArray< int32 > SelectedPointIDs Support for selection.
Protected variable TArray< FVector3d > SelectedPointStartPositions We need the selected point start positions so we can move multiple points appropriately.
Protected variable int32 ShiftModifierId  
Protected variable UE::Geometry::FPointPlanarSnapSolver SnapEngine  
Protected variable FColor SnapLineColor  

Destructors

  Type Name Description
Public function Virtual   Some other standard functions.

Functions

  Type Name Description
Public function void

AddSnapLine ( int32 LineID,
const UE::Geometry::FLine3d& Line
)

 Adds additional line to snap points to.
Public function int32

AppendPoint ( const FVector3d& PointCoordinates
)

  
Protected function void

ChangeSelection ( int32 NewPointID,
bool AddToSelection
)

 These issue undo/redo change objects, and must therefore not be called in undo/redo code.
Protected function void  
Public function void Clears all points in the mechanic.
Protected function void  
Protected function int32

DeletePoint ( int32 SequencePosition
)

  
Public function void Deletes currently selected points- can be called on a key press from the parent tool.
Protected function bool

DeselectPoint ( int32 PointID
)

  
Public function void Expires any changes currently associated with the mechanic in the undo/redo stack.
Public function void

ExtractPointPositions ( TArray< FVector3d >& PositionsOut
)

 Outputs the positions of the points in the control point sequence.
Public function bool Returns whether the underlying sequence of control points is a loop.
Public function int32 Gives number of points currently managed by the mechanic.
Protected function void Callbacks we'll receive from the gizmo proxy.
Protected function void  
Protected function void  
Protected function bool

HitTest ( const FInputDeviceRay& ClickPos,
FInputRayHit& ResultOut
)

  
Public function Virtual void

Initialize ( const TArray< FVector3d >& Points,
bool bIsLoop
)

 Functions used for initializing the mechanic.
Protected function int32

InsertPointAt ( int32 SequencePosition,
const FVector3d& NewPointCoordinates,
const int32* KnownPointID
)

 All of the following do not issue undo/redo change objects.
Public function bool  
Public function void

RemoveSnapLine ( int32 LineID
)

  
Protected function void

SelectPoint ( int32 PointID
)

  
Public function void When true, if the number of control points falls below the mins required (through deletion by the user), the mechanic automatically falls back into interactive intialization mode.
Public function void Interactive initialization mode allows the user to click multiple times to initialize the curve (without having to hold Ctrl), and to transition to edit mode by clicking the last or first points (provided the minimal numbers of points have been met)
Public function void

SetIsLoop ( bool bIsLoop
)

  
Public function void In interactive intialization mode, these minimums determine how many points must exist before initialization mode can be left.
Public function void

SetPlane ( const UE::Geometry::FFrame3d& DrawPlaneIn
)

 Sets the plane on which new points are added on the ends and in which the points are moved.
Public function void

SetSnappingEnabled ( bool bOn
)

 TODO: It is simple to allow the points to be moved arbitrarily, not just inside the plane, if we ever want to use the mechanic somewhere where that is desirable.
Public function void

SetWorld ( UWorld* World
)

  
Protected function void  
Protected function void  
Protected function void

UpdatePointLocation ( int32 PointID,
const FVector3d& NewLocation
)

  
Protected function void

UpdateSnapHistoryPoint ( int32 Index,
FVector3d NewPosition
)

  
Protected function void  

Overridden from UInteractionMechanic

  Type Name Description
Public function Virtual void Allow the Mechanic to do any custom drawing (ie via PDI/RHI)
Public function Virtual void

Setup ( UInteractiveTool* ParentTool
)

 Called to initialize the InteractionMechanic
Public function Virtual void Called to clean up the InteractionMechanic

Overridden from IClickBehaviorTarget

  Type Name Description
Public function Virtual FInputRayHit

IsHitByClick ( const FInputDeviceRay& ClickPos
)

 IClickBehaviorTarget implementation.
Public function Virtual void

OnClicked ( const FInputDeviceRay& ClickPos
)

 Notify Target that click ocurred

Overridden from IModifierToggleBehaviorTarget

  Type Name Description
Public function Virtual void

OnUpdateModifierState ( int ModifierID,
bool bIsOn
)

 IModifierToggleBehaviorTarget implementation, inherited through IClickBehaviorTarget.

Overridden from IHoverBehaviorTarget

  Type Name Description
Public function Virtual FInputRayHit IHoverBehaviorTarget implementation.
Public function Virtual void

OnBeginHover ( const FInputDeviceRay& DevicePos
)

 Initialize hover sequence at given position
Public function Virtual void Terminate active hover sequence
Public function Virtual bool

OnUpdateHover ( const FInputDeviceRay& DevicePos
)

 Update active hover sequence with new input position

Classes

  Type Name Description
Protected class FOrderedPoints We want some way to store the control point sequence that lets us easily associate points with their renderable and hit-testable representations, since we need to alter all of these together as points get moved or added.  

Typedefs

Name Description
OnModeChangedEvent This delegate is called when the mode of the mechanic changes (i.e., we leave or re-enter interactive initialization)
OnPointsChangedEvent This delegate is called every time the control point sequence is altered.

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