Get mesh data about realtimemeshcomponent HOT 4 CLOSED

Well if you built the mesh section manually you should definitely already know the tris, vertices, normals, UVs and vertex colors. If you created the section from one of the procedural methods of RMC then the outputs of the relevant parameters will tell you exactly what you want:

TArray<FVector>             Vertices;
TArray<int32>               Triangles;
TArray<FVector>             Normals;
TArray<FVector2D>           TextureCoords;
TArray<FRuntimeMeshTangent> Tangents;


URuntimeMeshLibrary::CreateBoxMesh(FVector(Size, Size, Size), Vertices, Triangles, Normals, TextureCoordinates, Tangents);

Where Vertices will be an array of vertex positions, Triangles will be an array of each vertex index in winding order, Normals will be an array of each triangle's normal in order and so on. With that you can determine that with this code:

int32 TriangleIndex;
TArray<FVector> TriangleVertices;

Triangle.Add(Vertices[Triangles[TriangleIndex * 3 + 0]]);
Triangle.Add(Vertices[Triangles[TriangleIndex * 3 + 1]]);
Triangle.Add(Vertices[Triangles[TriangleIndex * 3 + 2]]);

TriangleVertices will contain all 3 vertex positions of the triangle at TriangleIndex in winding order.

Also: knowing just the vertices and the indices you can get tris, normals, etc. Here's an accurate example of how to calculate the normals of a triangle index:

FVector CalculateTriangleNormal(int32 TriangleIndex)
{
	int32 VertOffset = TriangleIndex * 3;

	FVector Cross = FVector::CrossProduct(
		Vertices[Triangles[VertOffset + 2]] - Vertices[Triangles[VertOffset + 0]],  // Edge 1
		Vertices[Triangles[VertOffset + 1]] - Vertices[Triangles[VertOffset + 0]]); // Edge 2
	Cross.Normalize();

	return Cross;
}

I think you need to read this Wiki entry: Mesh Basics. I also recommend doing more research on 3D geometry to better understand how just knowing the vertex positions and windings can get you triangles, the normals of those triangles, tangents, etc.

PS: RMC is fucking awesome @Koderz, thanks for your hard work!

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Fair enough, thanks for the info @Zinglish

How would I get the Vertex Buffer info for a mesh? Although I created the mesh I dont want to hold all these values as I assume the RuntimeMeshComponent would. I just need a way to access the Vertex buffer whenever I need. Is it exposed?

from realtimemeshcomponent.

Again, you should do some more research and reading before opening an issue to talk about information that's readily available. There's examples on how to use RMC, in the Animated Terrain Demo you can see how to grab and use the vertex buffer. Regardless I will, for the sake of anyone who's stuck on this, provide a minimal approach below.

If you create a mesh doing something like

TArray<FRuntimeMeshVertexNoPosition> VertexData;

FBox BoundingBox = FBox(FVector(Size, Size, Size), FVector(-Size, -Size, -Size));

URuntimeMeshLibrary::CreateBoxMesh(FVector(Size, Size, Size), Vertices, Triangles, Normals, TextureCoordinates, Tangents);

for(int32 i = 0; i < Normals.Num(); i++)
		VertexData.Add(FRuntimeMeshVertexNoPosition(Normals[i], Tangents[i], TextureCoordinates[i]));

RMC->CreateMeshSectionDualBuffer(0, Vertices, VertexData, Triangles, BoundingBox, true, EUpdateFrequency::Frequent);

You can later get the vertex buffer with the following method

TArray<FVector>& Vertices = *RMC->BeginMeshSectionPositionUpdate(0);

You would then modify and vertices in the Vertices array then call RMC->EndMeshSectionPositionUpdate(0); which will force RMC to update the vertices in the UE4 renderer.

Do note that adding or removing any verts from the array returned from BeginMeshSectionPositionUpdate() will likely result in a crash or unexpected behaviour. If you wish to add or remove verts from your mesh, I believe you will need to rebuild it entirely, discarding all previous information about the mesh, I haven't experimented with this myself all that much tbh.

from realtimemeshcomponent.

I have no intention of updating an exisiting mesh so I really don't think using BeginMeshSectionPositionUpdate(0) is correct. It doesn't seem like it was meant to just get a reference.

Anyway, this worked for me -

const IRuntimeMeshVerticesBuilder* runtimeVertices;
const FRuntimeMeshIndicesBuilder* runtimeIndices;
Mesh->GetSectionMesh(0, runtimeVertices, runtimeIndices);

runtimeVertices now contains all vertex related data.

Thanks for your help @Zinglish.

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