The binary change stream the renderer reads: a sequence of operations, each a one-byte code and its fields, little-endian. encode/1 turns changes into it.

A change is one of:

• :tick — the changes that follow belong to a new game tick; poses are interpolated from the previous tick's
• {:mesh, id, %CauldronGPU.Mesh{}}, {:drop_mesh, id}
• {:texture, id, %CauldronGPU.Texture{}}, {:drop_texture, id}
• {:canvas, id, %CauldronGPU.Canvas{}} — a texture the renderer draws into, dropped as a texture is
• {:material, id, %CauldronGPU.Material{}}, {:drop_material, id}
• {:instance, id, %CauldronGPU.Instance{}}
• {:move, id, %CauldronGPU.Transform{}} or {:move, id, transform, snap: true}
• {:pose, id, %CauldronGPU.Pose{}} — bends instance id's mesh until the next pose
• {:remove_instance, id}
• {:light, id, %CauldronGPU.Light{}}, {:remove_light, id}
• %CauldronGPU.Camera{}
• %CauldronGPU.Environment{}

• {:light_styles, [scale | {r, g, b}]} — the brightness of light styles 0, 1, …, a number for all three colours or one each (1.0 normal, up to 64 styles; styles not listed stay as they were, 1.0 at first)

• {:overlay, texture_handle | nil} — a picture drawn over the finished frame, stretched to it, see-through by its alpha (a HUD, menus); nil removes it. {:overlay, texture_handle, :premultiplied} takes its colours as already multiplied by its alpha, so a pixel with colour and no alpha adds its colour (an additive HUD)

• {:screen_tint, {r, g, b, a}} — the finished frame's display colours blended towards the display colour {r, g, b} by a; the overlay is blended over display colours too
• {:layers, [layer]} — the 2D layers drawn each frame, in order, until the next :layers change; a layer is a CauldronGPU.SpriteLayer or a CauldronGPU.ColumnLayer, and {:layers, []} removes them
• {:effects, [effect]} with effects :ray_traced_shadows, :ray_traced_reflections, :ray_traced_global_illumination, :ray_traced_ambient_occlusion, :upscaling, :frame_generation; a renderer that cannot provide one ignores it

Ids are integers from 1 to 2³²−1. Positions and directions follow CauldronGPU.Transform's frame.