MovieSceneCondition.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "MovieSceneSequenceID.h"
#include "MovieSceneSignedObject.h"
#include "UObject/WeakObjectPtrTemplates.h"
#include "Containers/Array.h"
#include "MovieSceneBindingProxy.h"
#include "MovieSceneCondition.generated.h"
 
namespace UE
{
    namespace MovieScene
    {
        struct FSharedPlaybackState;
    }
}
 
/*
* Defines the scope of a particular condition type.
* By default, the condition scope will determine whether conditions need to be re-evaluated for different bindings or entities in the Sequence.
*/
UENUM(BlueprintType)
enum class EMovieSceneConditionScope : uint8
{
    /* Condition has the same result regardless of the binding or entity.*/
    Global,
    /* Condition may have different results for different object bindings. */
    Binding,
    /* Condition may have different results for each different outer object owner (i.e. track, section) in the Sequence.*/
    OwnerObject,
};
 
/* Defines how often a condition needs to be checked. 
*  Most conditions should return 'Once', but if the condition result can change during playback, 'OnTick' can be chosen to have the condition re-evaluated each tick.
*/
UENUM(BlueprintType)
enum class EMovieSceneConditionCheckFrequency : uint8
{
    /* Condition result will not change during sequence playback and only needs to get checked once. */
    Once,
    /* Condition result may change during sequence playback and should be checked per tick. */
    OnTick,
};
 
/*
* Blueprint-friendly struct containing any context needed to evaluate conditions. 
*/
USTRUCT(BlueprintType)
struct FMovieSceneConditionContext
{
GENERATED_BODY()
public:
 
    /* The world context*/
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Default")
    TObjectPtr<UObject> WorldContext;
    
    /* Binding for the bound object currently evaluating this condition if applicable (BindingId will be invalid for conditions on global tracks/sections). */
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Default")
    FMovieSceneBindingProxy Binding;
 
    /* Array of objects bound to the binding currently evaluating this condition if applicable (will be empty for conditions on global tracks/sections)*/
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Default")
    TArray<TObjectPtr<UObject>> BoundObjects;
};
 
/*
* Container struct for instanced UMovieSceneConditions, existing only to allow property type customization for choosing conditions.
*/
USTRUCT(BlueprintType)
struct FMovieSceneConditionContainer
{
    GENERATED_BODY()
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Instanced, Category="Sequencer|Condition", meta = (EditInline, AllowEditInlineCustomization))
    TObjectPtr<UMovieSceneCondition> Condition = nullptr;
};
 
UCLASS(abstract, Blueprintable, DefaultToInstanced, EditInlineNew, meta = (ShowWorldContextPin), CollapseCategories, MinimalAPI)
class UMovieSceneCondition
    : public UMovieSceneSignedObject
{
    GENERATED_BODY()
 
public:
 
    /* Called by Sequencer code to evaluate this condition, passing relevant context. Note that BindingGuid will be invalid for conditions on global sections/tracks. */
    MOVIESCENE_API bool EvaluateCondition(FGuid BindingGuid, FMovieSceneSequenceID SequenceID, TSharedRef<const UE::MovieScene::FSharedPlaybackState> SharedPlaybackState) const;
 
    /* Called by Sequencer to compute a cache key for this condition given the passed in context.
    *  By default, this key will be computed based on the Binding Scope, and if relevant, the binding and entity owner.
    * If a condition returns the same cache key given the same or different contexts, it will not be rechecked, and a cached value may be used.
    */
    MOVIESCENE_API virtual uint32 ComputeCacheKey(FGuid BindingGuid, FMovieSceneSequenceID SequenceID, TSharedRef<const UE::MovieScene::FSharedPlaybackState> SharedPlaybackState, UObject* EntityOwner) const;
 
    MOVIESCENE_API virtual bool CanCacheResult(TSharedRef<const UE::MovieScene::FSharedPlaybackState> SharedPlaybackState) const;
 
    MOVIESCENE_API EMovieSceneConditionScope GetConditionScope() const;
 
#if WITH_EDITORONLY_DATA
    /* If true, will skip evaluating the condition and always return true. Useful for authoring or debugging. */
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Default")
    bool bEditorForceTrue = false;
 
    friend class FMovieSceneConditionCustomization;
#endif
 
protected:
 
    /* Override to implement your condition.*/
    UFUNCTION(BlueprintImplementableEvent, CallInEditor, meta=(DisplayName = "On Evaluate Condition"))
    MOVIESCENE_API bool BP_EvaluateCondition(const FMovieSceneConditionContext& ConditionContext) const;
 
    /* Override in native code to implement your condition. Note that BindingGuid will be invalid for conditions on global sections/tracks.*/
    MOVIESCENE_API virtual bool EvaluateConditionInternal(FGuid BindingGuid, FMovieSceneSequenceID SequenceID, TSharedRef<const UE::MovieScene::FSharedPlaybackState> SharedPlaybackState) const;
    
    /* Returns the scope of the condition, which determines whether the condition needs to be re-evaluated for different bindings or entities in the Sequence. */
    UFUNCTION(BlueprintNativeEvent, CallInEditor, meta=(DisplayName = "Get Scope"))
    MOVIESCENE_API EMovieSceneConditionScope BP_GetScope() const;
 
    /* Returns the scope of the condition, which determines whether the condition needs to be re-evaluated for different bindings or entities in the Sequence. */
    MOVIESCENE_API virtual EMovieSceneConditionScope GetScopeInternal() const;
 
    /* Returns the check frequency of the condition, which determines whether the condition result can change during playback and needs to get re-evaluated. */
    UFUNCTION(BlueprintNativeEvent, CallInEditor, meta=(DisplayName = "Get Check Frequency"))
    MOVIESCENE_API EMovieSceneConditionCheckFrequency BP_GetCheckFrequency() const;
 
    /* Returns the check frequency of the condition, which determines whether the condition result can change during playback and needs to get re-evaluated. */
    MOVIESCENE_API virtual EMovieSceneConditionCheckFrequency GetCheckFrequencyInternal() const;
 
protected:
    /* If true, inverts the result of the condition check.*/
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Default")
    bool bInvert = false;
 
};