Rendering a lot of Models at once with XNA

Question

In an hexgrid based game, I render all terrain tiles as a separate model, reusing the same texture objects on all similar tiles. The tiles is a pretty simple model.

When the terrain is set to be at 20x20 or more (so 400 tiles), the game really slows down. The "slowdown point" is about the same on my i5 laptop or my i7 desktop. The game takes around 30megs in the memory. Here is how the render looks like :

The way I render each tile is the following :

foreach (ModelMesh mesh in ModelSupport.Meshes)
{
    foreach (BasicEffect effect in mesh.Effects)
    {
        effect.EnableDefaultLighting();
        effect.World = transforms[mesh.ParentBone.Index] 
            * mScale * mRotationY * mPosition;
        effect.View = Camera.ViewMatrix;
        effect.Projection = Camera.ProjectionMatrix;
    }

    mesh.Draw();
}

Any suggestion of how I could optimize the rendering of a large amount of models?

Answer 1

I believe you want hardware instancing.

http://xbox.create.msdn.com/en-US/education/catalog/sample/mesh_instancing

Answer 2

If you're really rendering each tile as a static hexagonal model, then you're wasting a lot of resources on the side faces that will not be visible.

Think about doing it like Minecraft, instead: generate the side faces programmatically (or create them as separate models from the top), and include each face only if its tile is higher than its neighbor in that direction, and make them no taller than necessary. Take a reasonably-sized bunch of such computed tiles and put them all in one vertex array.