Combine Mesh

[alcoranpaul]

How to Combine Meshes in Flax Engine Here are a few ways to combine meshes in Flax:

1. Manually Combining Meshes If you're procedurally generating your dungeon, you can manually combine meshes into a single larger mesh. Here's a high-level outline of the process:

• Get Mesh Data: For each tile or object you want to combine, extract its mesh data (vertices, triangles, etc.).
• Merge Vertices & Triangles: Append the vertices and triangle indices of each object into a single larger mesh. You may need to transform the vertices based on each tile's position in the world.
• Create a New Combined Mesh: Once the data is merged, create a new mesh from the combined data.

Example Workflow:

1. Get vertex and index data from the individual meshes.
2. Transform the vertices based on their local position.
3. Append all vertex and index data into a single large buffer.
4. Create a new mesh from the combined data.

Here’s an example of what the steps might look like conceptually in code:

List<Vector3> combinedVertices = new List<Vector3>();
List<int> combinedTriangles = new List<int>();
int vertexOffset = 0;

foreach (Mesh mesh in meshesToCombine)
{
    // Get vertices and triangles from each mesh
    Vector3[] vertices = mesh.GetVertices();
    int[] triangles = mesh.GetTriangles();

    // Transform vertices by the mesh's world position (if necessary)
    for (int i = 0; i < vertices.Length; i++)
    {
        vertices[i] = mesh.transform.LocalToWorld(vertices[i]);
        combinedVertices.Add(vertices[i]);
    }

    // Adjust triangles based on the current vertex count
    for (int i = 0; i < triangles.Length; i++)
    {
        combinedTriangles.Add(triangles[i] + vertexOffset);
    }

    // Increase vertexOffset by the number of vertices in this mesh
    vertexOffset += vertices.Length;
}

// Create a new mesh with the combined vertices and triangles
Mesh combinedMesh = new Mesh();
combinedMesh.SetVertices(combinedVertices.ToArray());
combinedMesh.SetTriangles(combinedTriangles.ToArray());

2. Use Static Batching (Static Mesh Combiner) Flax Engine supports static batching, which automatically combines static meshes at runtime for optimization. Here's how you can use static batching:

Mark objects as static: You can set an object’s static flag to let the engine know that it won't move. This allows the engine to optimize these objects by combining their meshes and reducing draw calls.

You can do this in the Flax Editor by selecting your objects and marking them as static.

3. Use GPU Instancing If combining meshes isn’t feasible (e.g., because objects need to be individually interactable), consider GPU instancing. This allows the engine to render multiple instances of the same mesh efficiently by sending a single draw call to the GPU for multiple objects with the same geometry.

In Flax, instancing works automatically for certain scenarios, but you can also control it manually depending on your needs. For example, if you're using the same tile mesh for floors or walls, instancing will let the engine render them more efficiently.

4. Use LOD (Level of Detail) with Combined Meshes If you combine meshes for distant tiles or large grid sections, you can apply LOD (Level of Detail) techniques, where the combined mesh uses fewer details for tiles farther from the camera. This can be especially helpful in open areas like large dungeons, where distant objects don’t need to be rendered at full detail.

Performance Tips:

• Static Mesh Combiner: Use it for static objects in your scene, such as floors, walls, or rooms that don’t change after they’re placed.
• Limit Dynamic Objects: Only combine meshes for static objects. Dynamic objects should remain separate for individual updates and physics interactions.
• Optimize Vertices and UVs: When combining meshes, make sure that you manage vertices and UVs correctly, especially for texture mapping. You may need to adjust UV coordinates if you're applying a texture atlas to the combined mesh. By combining meshes strategically and using techniques like static batching, you can significantly reduce draw calls and improve performance in large, grid-based dungeon systems in Flax Engine.