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Manipulating skeletal mesh vertex positions at runtime

Hey guys, I'm quite new to C++ programming (I much prefer C#) but I have a bit of experience with the engine itself (material creation etc.) and I've run into a bit of a problem. I'm trying to manipulate the vertex positions of a skeletal mesh at runtime without the editor. At first the engine crashed but I was able to fix that due to an array index being out of bounds. The real question I'm having is how can I update the mesh after the positions have been updated and to also fix a memory leak I'm having as well?

The code in question is here (no need for the header file as there's not much other than the void function).

 #include "UpdateVertex.h"
 #include "SkeletalMeshTypes.h"
 #include "Engine/Public/Rendering/SkeletalMeshLODRenderData.h"
 #include "Engine/Public/Rendering/SkeletalMeshRenderData.h"
 #include "Engine/SkeletalMesh.h"
 #include "Components/SkinnedMeshComponent.h"
 #include "Components/SkeletalMeshComponent.h"
 #include "Engine.h"
 
 //DOESN'T UPDATE MESH AND CAUSES HUGE MEMORY LEAK OF OVER 200MB
 void UUpdateVertex::Update(USkeletalMeshComponent* SkeletalMeshComp, int32 LodIndex)
 {
     //Avoid running if no skeletal mesh was found
     if (!SkeletalMeshComp->SkeletalMesh)
     {
         UE_LOG(LogTemp, Warning, TEXT("No skeletal mesh found!"));
         return;
     }
     USkeletalMesh* SkelMesh = SkeletalMeshComp->SkeletalMesh;
 
     FSkeletalMeshRenderData* RenderData = SkelMesh->GetResourceForRendering();
 
     //Avoid crashing if index is higher than meshes LOD count
     if (LodIndex > SkelMesh->GetLODNum())
     {
         UE_LOG(LogTemp, Warning, TEXT("LOD greater than index!"));
         return;
     }
     FSkeletalMeshLODRenderData& LodRender = RenderData->LODRenderData[LodIndex];
 
 
     //Update every vertex position in every render section
     for (int32 j = 0; j < LodRender.RenderSections.Num(); j++)
     {
         for (int32 i = 0; i < LodRender.RenderSections[j].GetNumVertices(); i++)
         {
             LodRender.StaticVertexBuffers.PositionVertexBuffer.VertexPosition(i) += FVector(0.0f, 0.0f, 10.0f);
             UE_LOG(LogTemp, Warning, TEXT("Vertex position: %s"), *LodRender.StaticVertexBuffers.PositionVertexBuffer.VertexPosition(i).ToString());
         }
     }
     //FSkeletalMeshLODRenderData* LodRender = RenderData->LODRenderData;
     
     SkeletalMeshComp->MarkRenderStateDirty();
 }


I'm planning on separating the variables into an init function if that helps with the memory leak.

Product Version: UE 4.20
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asked Oct 30 '18 at 07:17 AM in Rendering

avatar image

LeStErThEmOlEsT
6 1 3

avatar image LeStErThEmOlEsT Nov 02 '18 at 09:03 AM

Okay so I fixed the memory leak, turns out it was just the spamming of output logs in the 'for loop' that caused the RAM to go up like that. However, I still haven't found a way for the updated vertex positions to render...

avatar image HarryHighDef Nov 02 '18 at 09:23 AM

Do you only want to add 10 units on Z to each vertex?

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