Rendering in Mibo

Mibo’s rendering story is intentionally simple:

• Your Elmish update stays pure.
• Your view function submits render commands to a RenderBuffer.
• A renderer (IRenderer<'Model>) executes those commands each frame.

This keeps drawing as data submission, which composes nicely as projects grow.

Renderers are just IRenderer<'Model>

A renderer is anything that implements:

type IRenderer<'Model> =
    abstract member Draw: GameContext * 'Model * GameTime -> unit

You add renderers with:

Program.withRenderer (fun game -> myRenderer :> IRenderer<Model>)

Multiple renderers can be added (e.g. 3D world + 2D UI). They run in the order they were added.

The RenderBuffer pattern

Instead of drawing immediately inside update, you typically:

1. allocate a buffer (owned by the renderer)
2. clear it each frame
3. call your view to fill it
4. optionally sort it
5. execute the commands

The built-in renderers follow this pattern, and custom renderers can too.

Writing your own renderer

If you have a custom draw pipeline (special post-processing, instancing, debug overlays, etc), implement IRenderer<'Model>.

Minimal example:

type MyRenderer(game: Game) =
    interface IRenderer<Model> with
        member _.Draw(ctx, model, gameTime) =
            // use ctx.GraphicsDevice, ctx.Content, etc
            // draw based on model
            ()

Then install it:

Program.mkProgram init update
|> Program.withRenderer (fun game -> MyRenderer(game) :> IRenderer<Model>)

Built-in renderers

Mibo includes:

• 2D SpriteBatch renderer: Mibo.Elmish.Graphics2D.Batch2DRenderer
• 3D renderer with pass handling and primitive batching: Mibo.Elmish.Graphics3D.Batch3DRenderer

See the dedicated pages:

• Rendering 2D
• Rendering 3D
• Camera
• Culling