Multiple Cameras and Passes

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A ModelBatch can be flushed more than once per frame. Each flush draws everything rendered since the last flush with its own camera and render pass.

A Second Camera

Creates a top down camera and a texture to render it into, such as a minimap.

val minimapCamera = PerspectiveCamera(256, 256)
minimapCamera.translate(0f, 30f, 0f)
minimapCamera.rotate((-90).degrees, Vec3f.X_AXIS)

val minimap = EmptyTexture(device, preferredFormat, 256, 256)

Rendering

Render the models again for each camera before flushing to its render pass.

onUpdate { dt ->
    camera.update()
    minimapCamera.update()

    // pass 1: the minimap camera
    val minimapPass = ... // render pass using minimap.view
    models.forEach { modelBatch.render(it, minimapCamera, environment) }
    modelBatch.flush(minimapPass, minimapCamera, dt)
    minimapPass.end()

    // pass 2: the main camera
    val mainPass = ... // render pass using the surface frame
    models.forEach { modelBatch.render(it, camera, environment) }
    modelBatch.flush(mainPass, camera, dt)
    mainPass.end()
}

Drawing the Minimap

The minimap can then be drawn on top of the frame with a SpriteBatch, just like a render target.

val uiPass = ... // render pass using the surface frame with LoadOp.LOAD
spriteBatch.begin(uiCamera.viewProjection)
spriteBatch.draw(minimap, 10f, 10f)
spriteBatch.flush(uiPass)
spriteBatch.end()
uiPass.end()

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