Scenes and SceneLayers

A Scene is Gondwana’s top-level world container. It owns a set of SceneLayer instances, tracks global collision groups, and acts as the unit a render surface binds to when the engine draws a frame.

A SceneLayer is where most playable world content actually lives. Each layer has:

• its own tile grid
• its own coordinate system
• its own parallax factor
• its own dirty-region RefreshQueue
• its own collision registry and resolver
• its own visibility and z-order

This is one of Gondwana’s most important architectural foundations: the engine does not treat “the world” as a single flat canvas. Instead, it treats the world as a stack of independently managed layers.

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Why that matters

Because each SceneLayer tracks refresh state independently, Gondwana can redraw only the layers and world regions that changed. That makes layered backgrounds, gameplay layers, collision-debug overlays, and HUD-style scene content practical without forcing a full-frame redraw every cycle.

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Mental model

Think of a Scene as a folder, and each SceneLayer as a transparent sheet inside it:

• some layers move slower (Parallax < 1)
• some move normally (Parallax = 1)
• some can move faster (Parallax > 1)
• each can use a different projection model
• each can be hidden, reordered, shifted, or wrapped

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Key details

• Scene.VisibleSceneLayers is cached and sorted by ascending ZOrder
• structural layer changes mark Scene.FullRefreshNeeded = true
• layer origin is in world pixels
• tile addressing is still layer-local
• collision groups live at scene level, but layers expose them as a convenience

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Where to read next

• Gondwana/Scenes/Scene.cs
• Gondwana/Scenes/SceneLayer.cs
• Gondwana/Rendering/RefreshQueue.cs