【UE4 C++】动态修改材质参数

普通使用

• 注意GC，例如在slate调用时，可能会一段时间后由此造成材质丢失或系统崩溃

  //头文件
  UMaterialInstanceDynamic* PointerMaterial;
  UMaterialInstanceDynamic* MiniMapmatInstDynamic;
  
  //构造函数调用
  static ConstructorHelpers::FObjectFinder<UMaterialInstance> StaticPointMaterialIns(TEXT("MaterialInstanceConstant'/Game/Material/M_PointInst.M_PointInst'"));
  PointerMaterial = (UMaterialInstanceDynamic*)StaticPointMaterialIns.Object;
  
  // 普通函数调用
  static UMaterialInterface* MiniMapmatInst = LoadObject<UMaterialInterface>(NULL, TEXT("MaterialInstanceConstant'/Game/Material/M_MiniMapInst.M_MiniMapInst'"));
  UMaterialInstanceDynamic MiniMapmatInstDynamic = UMaterialInstanceDynamic::Create(MiniMapmatInst, nullptr);
  
  // 设置参数
  PointerMaterial->SetScalarParameterValue(FName("Range"), Range);
  
  MiniMapmatInstDynamic->SetTextureParameterValue(FName("MiniMapTex"), MiniMapRender);
  

---

为UStaticMeshComponent 创建

• 几个函数

  /**
  	 * Creates a Dynamic Material Instance for the specified element index.  The parent of the instance is set to the material being replaced.
  	 * @param ElementIndex - The index of the skin to replace the material for.  If invalid, the material is unchanged and NULL is returned.
  	 */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "CreateMIDForElement", DeprecatedFunction, DeprecationMessage="Use CreateDynamicMaterialInstance instead."), Category="Rendering|Material")
  	virtual class UMaterialInstanceDynamic* CreateAndSetMaterialInstanceDynamic(int32 ElementIndex);
  
  	/**
  	 * Creates a Dynamic Material Instance for the specified element index.  The parent of the instance is set to the material being replaced.
  	 * @param ElementIndex - The index of the skin to replace the material for.  If invalid, the material is unchanged and NULL is returned.
  	 */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "CreateMIDForElementFromMaterial", DeprecatedFunction, DeprecationMessage="Use CreateDynamicMaterialInstance instead."), Category="Rendering|Material")
  	virtual class UMaterialInstanceDynamic* CreateAndSetMaterialInstanceDynamicFromMaterial(int32 ElementIndex, class UMaterialInterface* Parent);
  
  	/**
  	 * Creates a Dynamic Material Instance for the specified element index, optionally from the supplied material.
  	 * @param ElementIndex - The index of the skin to replace the material for.  If invalid, the material is unchanged and NULL is returned.
  	 */
  	UFUNCTION(BlueprintCallable, Category="Rendering|Material")
  	virtual class UMaterialInstanceDynamic* CreateDynamicMaterialInstance(int32 ElementIndex, class UMaterialInterface* SourceMaterial = NULL, FName OptionalName = NAME_None);
  

---

附录

• UMaterialInstanceDynamic 源码

  UCLASS(hidecategories=Object, collapsecategories, BlueprintType)
  class ENGINE_API UMaterialInstanceDynamic : public UMaterialInstance
  {
  	GENERATED_UCLASS_BODY()
  
  	/** Set a MID scalar (float) parameter value */
  	UFUNCTION(BlueprintCallable, meta=(Keywords = "SetFloatParameterValue"), Category="Rendering|Material")
  	void SetScalarParameterValue(FName ParameterName, float Value);
  
  	/** Set a MID scalar (float) parameter value using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, meta = (Keywords = "SetFloatParameterValue"), Category = "Rendering|Material")
  	void SetScalarParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo, float Value);
  
  	// NOTE: These Index-related functions should be used VERY carefully, and only in cases where optimization is
  	// critical.  Generally that's only if you're using an unusually high number of parameters in a material AND
  	// setting a huge number of parameters in the same frame.
  
  	// Use this function to set an initial value and fetch the index for use in the following function.
  	bool InitializeScalarParameterAndGetIndex(const FName& ParameterName, float Value, int32& OutParameterIndex);
  	// Use the cached value of OutParameterIndex above to set the scalar parameter ONLY on the exact same MID
  	bool SetScalarParameterByIndex(int32 ParameterIndex, float Value);
  
  	// Use this function to set an initial value and fetch the index for use in the following function.
  	bool InitializeVectorParameterAndGetIndex(const FName& ParameterName, const FLinearColor& Value, int32& OutParameterIndex);
  	// Use the cached value of OutParameterIndex above to set the vector parameter ONLY on the exact same MID
  	bool SetVectorParameterByIndex(int32 ParameterIndex, const FLinearColor& Value);
  
  	/** Get the current scalar (float) parameter value from an MID */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "GetScalarParameterValue", ScriptName = "GetScalarParameterValue", Keywords = "GetFloatParameterValue"), Category="Rendering|Material")
  	float K2_GetScalarParameterValue(FName ParameterName);
  
  	/** Get the current scalar (float) parameter value from an MID, using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, meta = (DisplayName = "GetScalarParameterValueByInfo", ScriptName = "GetScalarParameterValueByInfo", Keywords = "GetFloatParameterValue"), Category = "Rendering|Material")
  	float K2_GetScalarParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo);
  
  	/** Set an MID texture parameter value */
  	UFUNCTION(BlueprintCallable, Category="Rendering|Material")
  	void SetTextureParameterValue(FName ParameterName, class UTexture* Value);
  
  	/** Set an MID texture parameter value using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, Category = "Rendering|Material")
  	void SetTextureParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo, class UTexture* Value);
  
  	/** Get the current MID texture parameter value */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "GetTextureParameterValue", ScriptName = "GetTextureParameterValue"), Category="Rendering|Material")
  	class UTexture* K2_GetTextureParameterValue(FName ParameterName);
  
  	/** Get the current MID texture parameter value, using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, meta = (DisplayName = "GetTextureParameterValueByInfo", ScriptName = "GetTextureParameterValueByInfo"), Category = "Rendering|Material")
  	class UTexture* K2_GetTextureParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo);
  
  	/** Set an MID vector parameter value */
  	UFUNCTION(BlueprintCallable, meta=(Keywords = "SetColorParameterValue"), Category="Rendering|Material")
  	void SetVectorParameterValue(FName ParameterName, FLinearColor Value);
  
  	/** Set an MID vector parameter value, using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, meta = (Keywords = "SetColorParameterValue"), Category = "Rendering|Material")
  	void SetVectorParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo, FLinearColor Value);
  
  	/** Get the current MID vector parameter value */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "GetVectorParameterValue", ScriptName = "GetVectorParameterValue", Keywords = "GetColorParameterValue"), Category="Rendering|Material")
  	FLinearColor K2_GetVectorParameterValue(FName ParameterName);
  
  	/** Get the current MID vector parameter value, using MPI (to allow access to layer parameters) */
  	UFUNCTION(BlueprintCallable, meta = (DisplayName = "GetVectorParameterValueByInfo", ScriptName = "GetVectorParameterValueByInfo", Keywords = "GetColorParameterValue"), Category = "Rendering|Material")
  	FLinearColor K2_GetVectorParameterValueByInfo(const FMaterialParameterInfo& ParameterInfo);
  	
  	/**
  	 * Interpolates the scalar and vector parameters of this material instance based on two other material instances, and an alpha blending factor
  	 * The output is the object itself (this).
  	 * Supports the case SourceA==this || SourceB==this
  	 * Both material have to be from the same base material
  	 * @param SourceA value that is used for Alpha=0, silently ignores the case if 0
  	 * @param SourceB value that is used for Alpha=1, silently ignores the case if 0
  	 * @param Alpha usually in the range 0..1, values outside the range extrapolate
  	 */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "InterpolateMaterialInstanceParameters", ScriptName = "InterpolateMaterialInstanceParameters"), Category="Rendering|Material")
  	void K2_InterpolateMaterialInstanceParams(UMaterialInstance* SourceA, UMaterialInstance* SourceB, float Alpha);
  
  	/**
  	 * Copies over parameters given a material interface (copy each instance following the hierarchy)
  	 * Very slow implementation, avoid using at runtime. Hopefully we can replace it later with something like CopyInterpParameters()
  	 * The output is the object itself (this). Copying 'quick parameters only' will result in a much
  	 * faster copy process but will only copy dynamic scalar, vector and texture parameters on clients.
  	 * @param bQuickParametersOnly Copy scalar, vector and texture parameters only. Much faster but may not include required data
  	 */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "CopyMaterialInstanceParameters", ScriptName = "CopyMaterialInstanceParameters"), Category="Rendering|Material")
  	void K2_CopyMaterialInstanceParameters(UMaterialInterface* Source, bool bQuickParametersOnly = false);
  
  	/**
  	* Copies the uniform parameters (scalar, vector and texture) from a material or instance hierarchy.
  	* This will typically be faster than parsing all expressions but still slow as it must walk the full
  	* material hierarchy as each parameter may be overridden at any level in the chain.
  	* Note: This will not copy static or font parameters
  	*/
  	void CopyMaterialUniformParameters(UMaterialInterface* Source);
  
  	/**
  	 * Copies over parameters given a material instance (only copy from the instance, not following the hierarchy)
  	 * much faster than K2_CopyMaterialInstanceParameters(), 
  	 * The output is the object itself (this).
  	 * @param Source ignores the call if 0
  	 */
  	UFUNCTION(meta=(DisplayName = "CopyInterpParameters"), Category="Rendering|Material")
  	void CopyInterpParameters(UMaterialInstance* Source);
  
  	/**
  	 * Create a material instance dynamic parented to the specified material.
  	 */
  	static UMaterialInstanceDynamic* Create(class UMaterialInterface* ParentMaterial, class UObject* InOuter);
  
  	/**
  	* Create a material instance dynamic parented to the specified material with the specified name.
  	*/
  	static UMaterialInstanceDynamic* Create( class UMaterialInterface* ParentMaterial, class UObject* InOuter, FName Name );
  
  	/**
  	 * Set the value of the given font parameter.  
  	 * @param ParameterName - The name of the font parameter
  	 * @param OutFontValue - New font value to set for this MIC
  	 * @param OutFontPage - New font page value to set for this MIC
  	 */
  	void SetFontParameterValue(const FMaterialParameterInfo& ParameterInfo, class UFont* FontValue, int32 FontPage);
  
  	/** Remove all parameter values */
  	void ClearParameterValues();
  
  	/**
  	 * Copy parameter values from another material instance. This will copy only
  	 * parameters explicitly overridden in that material instance!!
  	 */
  	UFUNCTION(BlueprintCallable, meta=(DisplayName = "CopyParameterOverrides"), Category="Rendering|Material")
  	void CopyParameterOverrides(UMaterialInstance* MaterialInstance);
  		
  	/**
  	 * Copy all interpolatable (scalar/vector) parameters from *SourceMaterialToCopyFrom to *this, using the current QualityLevel and given FeatureLevel
  	 * For runtime use. More specialized and efficient than CopyMaterialInstanceParameters().
  	 */
  	void CopyScalarAndVectorParameters(const UMaterialInterface& SourceMaterialToCopyFrom, ERHIFeatureLevel::Type FeatureLevel);
  
  	virtual bool HasOverridenBaseProperties()const override{ return false; }
  
  	//Material base property overrides. MIDs cannot override these so they just grab from their parent.
  	virtual float GetOpacityMaskClipValue() const override;
  	virtual bool GetCastDynamicShadowAsMasked() const override;
  	virtual FMaterialShadingModelField GetShadingModels() const override;
  	virtual bool IsShadingModelFromMaterialExpression() const override;
  	virtual EBlendMode GetBlendMode() const override;
  	virtual bool IsTwoSided() const override;
  	virtual bool IsDitheredLODTransition() const override;
  	virtual bool IsMasked() const override;
  
  	/**
  	 * In order to remap to the correct texture streaming data, we must keep track of each texture renamed.
  	 * The following map converts from a texture from the dynamic material to the texture from the static material.
  	 * The following map converts from a texture from the dynamic material to the texture from the static material.
  	 */
  	TMap<FName, TArray<FName> > RenamedTextures;
  	
  	// This overrides does the remapping before looking at the parent data.
  	virtual float GetTextureDensity(FName TextureName, const struct FMeshUVChannelInfo& UVChannelData) const override;
  
  };