FreeRotationSubGizmo.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "BaseBehaviors/BehaviorTargetInterfaces.h"
#include "InteractiveGizmo.h"
#include "Math/MathFwd.h"
 
#include "FreeRotationSubGizmo.generated.h"
 
class IGizmoAxisSource;
class IGizmoClickTarget;
class IGizmoStateTarget;
class IGizmoTransformSource;
class UClickDragInputBehavior;
class UGizmoViewContext;
namespace UE::GizmoUtil
{
    struct FTransformSubGizmoCommonParams;
    struct FTransformSubGizmoSharedState;
}
 
UCLASS(MinimalAPI)
class UFreeRotationSubGizmo : public UInteractiveGizmo, public IClickDragBehaviorTarget, public IHoverBehaviorTarget
{
    GENERATED_BODY()
 
public:
    bool InitializeAsRotationGizmo(
        const UE::GizmoUtil::FTransformSubGizmoCommonParams& InitializationParams,
        UGizmoViewContext* ViewContext,
        UE::GizmoUtil::FTransformSubGizmoSharedState* SharedState);
    
    // There are many potential approaches to doing a free rotate handle. Currently we
    //  implement IncrementalSphereBound from the below, which feels pretty intuitive,
    //  but we could add the other ones if desired.
    //enum class EMode
    //{
    //  // Intersect rays with a sphere and rotate the latest result such that the previous 
    //  //  intersection goes to the latest intersection. Outside of sphere, assume you are
    //  //  on the tangent side of the sphere.
    //  // This is similar to how the normal editor gizmo works if you enable arcball rotation.
    //  IncrementalSphereBound,
    //  
    //  // Like IncrementalSphereBound, but rotate the original (not latest) transform such
    //  //  that the first (i.e. original) intersection goes to latest intersection.
    //  // This is similar to how the ball works in the new gizmos (i.e. if Enable New Gizmos) is true.
    //  SourceToDestSphereBound,
 
    //  // Similar to SourceToDestSphereBound in that we're determining our rotation axis based on
    //  //  the first intersection going to latest intersection, but the amount to rotate is determined
    //  //  by the distance in the camera plane, so that we can keep rotating the object 360 degrees or
    //  //  more with one drag.
    //  SourceToDestUnbounded
    //};
    //void SetMode(EMode::ModeIn);
    
    void SetUnscaledSphereRadius(double Radius) { UnscaledSphereRadius = Radius; }
 
    void SetShowSphereBoundsDuringInteraction(bool bOn) { bShowSphereBoundsDuringInteraction = bOn; }
 
    // UInteractiveGizmo overrides
    virtual void Setup() override;
    virtual void Render(IToolsContextRenderAPI* RenderAPI) override;
    virtual void Tick(float DeltaTime) override;
 
    // IClickDragBehaviorTarget implementation
    virtual FInputRayHit CanBeginClickDragSequence(const FInputDeviceRay& PressPos) override;
    virtual void OnClickPress(const FInputDeviceRay& PressPos) override;
    virtual void OnClickDrag(const FInputDeviceRay& DragPos) override;
    virtual void OnClickRelease(const FInputDeviceRay& ReleasePos) override;
    virtual void OnTerminateDragSequence() override;
 
    // IHoverBehaviorTarget implementation
    virtual FInputRayHit BeginHoverSequenceHitTest(const FInputDeviceRay& PressPos) override;
    virtual void OnBeginHover(const FInputDeviceRay& DevicePos) override;
    virtual bool OnUpdateHover(const FInputDeviceRay& DevicePos) override;
    virtual void OnEndHover() override;
 
public:
    // The below properties can be manipulated for more fine-grained control, but typically it is sufficient
    // to use the initialization method above.
 
    UPROPERTY()
    TScriptInterface<IGizmoAxisSource> AxisSource;
    
    UPROPERTY()
    TScriptInterface<IGizmoClickTarget> HitTarget;
 
    UPROPERTY()
    TScriptInterface<IGizmoStateTarget> StateTarget;
 
    UPROPERTY()
    TScriptInterface<IGizmoTransformSource> TransformSource;
 
    UPROPERTY()
    TObjectPtr<UGizmoViewContext> GizmoViewContext = nullptr;
 
    UPROPERTY()
    TObjectPtr<UClickDragInputBehavior> MouseBehavior;
    
private:
    bool bInInteraction = false;
    bool bShowSphereBoundsDuringInteraction = true;
 
    FVector LastSphereIntersectionPoint;
    double InteractionSphereRadius = 0;
    bool ClickPress_IncrementalSphereBound(const FInputDeviceRay& PressPos);
    bool ClickDrag_IncrementalSphereBound(const FInputDeviceRay& DragPos);
    
    double UnscaledSphereRadius = 100;
 
    // Helper that can hold some extra upkeep to do during Tick (used to
    //  update a camera axis source if needed).
    TUniqueFunction<void(float DeltaTime)> CustomTickFunction;
};