MeshComponentHelper.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Materials/Material.h"
#include "Materials/MaterialRelevance.h"
#include "Materials/MaterialInterface.h"
#include "MaterialDomain.h"
#include "RHIFeatureLevel.h"
 
class FMeshComponentHelper
{
public:
    template<class T>
    static FMaterialRelevance GetMaterialRelevance(const T& Component, EShaderPlatform InShaderPlatform);
 
    template<class T>
    static void GetMaterialSlotsOverlayMaterial(const T& Component, TArray<TObjectPtr<UMaterialInterface>>& OutMaterialSlotOverlayMaterials);
};
 
template<class T>
FMaterialRelevance FMeshComponentHelper::GetMaterialRelevance(const T& Component, EShaderPlatform InShaderPlatform)
{
    // Combine the material relevance for all materials.
    FMaterialRelevance Result;
    for (int32 ElementIndex = 0; ElementIndex < Component.GetNumMaterials(); ElementIndex++)
    {
        UMaterialInterface const* MaterialInterface = Component.GetMaterial(ElementIndex);
        if (!MaterialInterface)
        {
            MaterialInterface = UMaterial::GetDefaultMaterial(MD_Surface);
        }
        Result |= MaterialInterface->GetRelevance_Concurrent(InShaderPlatform);
    }
 
    TArray<TObjectPtr<UMaterialInterface>> AssetAndComponentMaterialSlotsOverlayMaterial;
    Component.GetMaterialSlotsOverlayMaterial(AssetAndComponentMaterialSlotsOverlayMaterial);
    bool bAllMaterialSlotOverride = true;
    for (const TObjectPtr<UMaterialInterface>& MaterialInterface : AssetAndComponentMaterialSlotsOverlayMaterial)
    {
        if (MaterialInterface)
        {
            Result |= MaterialInterface->GetRelevance_Concurrent(InShaderPlatform);
        }
        else
        {
            bAllMaterialSlotOverride = false;
        }
    }
 
    //If all material slot set an overlay material we wont use the global one
    if (!bAllMaterialSlotOverride)
    {
        UMaterialInterface const* OverlayMaterialInterface = Component.GetOverlayMaterial();
        if (OverlayMaterialInterface != nullptr)
        {
            Result |= OverlayMaterialInterface->GetRelevance_Concurrent(InShaderPlatform);
        }
    }
 
    return Result;
}
 
template<class T>
void FMeshComponentHelper::GetMaterialSlotsOverlayMaterial(const T& Component, TArray<TObjectPtr<UMaterialInterface>>& OutMaterialSlotOverlayMaterials)
{
    //Add all the component override
    OutMaterialSlotOverlayMaterials = Component.GetComponentMaterialSlotsOverlayMaterial();
 
    //Get the asset material slot overlay material
    TArray<TObjectPtr<UMaterialInterface>> AssetMaterialSlotOverlayMaterials;
    Component.GetDefaultMaterialSlotsOverlayMaterial(AssetMaterialSlotOverlayMaterials);
 
    //For each slot not override by the component set the asset slot value
    for (int32 SlotIndex = 0; SlotIndex < AssetMaterialSlotOverlayMaterials.Num(); ++SlotIndex)
    {
        if (!OutMaterialSlotOverlayMaterials.IsValidIndex(SlotIndex))
        {
            OutMaterialSlotOverlayMaterials.AddZeroed();
        }
        //If the component did not already override this slot index put the asset value
        if (!OutMaterialSlotOverlayMaterials[SlotIndex])
        {
            OutMaterialSlotOverlayMaterials[SlotIndex] = AssetMaterialSlotOverlayMaterials[SlotIndex];
        }
    }
}