How does Godot decide draw order?

Godot draws by CanvasLayer first, then within a layer by z_index, then by tree order. The default layer is 0; HUD elements typically live on a CanvasLayer with layer 1 or higher. A TileMap with z_index 10 on layer 0 will still draw below any node on layer 1 because layer ordering takes precedence over z_index.

Why is my HUD behind the TileMap even on a CanvasLayer?

Either the CanvasLayer’s layer property is ≤ 0, or you have a second CanvasLayer for the game world with a higher layer index. Check the inspector for both: HUD CanvasLayer.layer should be at least 1; world CanvasLayer (if any) should be 0 or negative. Save and reload the scene to confirm changes aren’t lost.

Do I need a CanvasLayer for a static HUD?

Yes, if your camera moves. Nodes outside a CanvasLayer follow the active Camera2D transform; HUD elements need to stay fixed on screen. A CanvasLayer uses its own transform independent of the camera, which is exactly what a HUD needs.

Fix: Godot CanvasLayer Not Rendering Above TileMap

Quick answer: Set the HUD CanvasLayer.layer to at least 1 (default is 0). Layer ordering wins over z_index — even a TileMap with z_index 100 sits below a CanvasLayer with layer 1.

You drop a label into a CanvasLayer, parent it to the root, and run the game. The TileMap is rendering over the top of the label. You bump z_index on the label. Nothing changes. You bump it to 1000. Still hidden. The reason is that layer beats z_index in Godot’s 2D ordering rules — and the layer defaults to 0.

The Three-Tier Sort Order

Godot 2D drawing is sorted in this order:

CanvasLayer.layer — higher draws later (on top). Default 0.
Node z_index — within a layer, higher draws later. Default 0.
Scene tree order — within the same z_index, later siblings draw on top.

This means a TileMap with z_index 5 on layer 0 will draw below any node on layer 1, regardless of z_index. The layer index trumps the z_index.

The Fix

Open the HUD CanvasLayer in the scene tree, select it, and in the Inspector set Layer to 1 (or higher):

# hud.tscn structure
HUD (CanvasLayer)
  layer = 1            # the critical value
  follow_viewport_enabled = false
  ScoreLabel (Label)
  HealthBar (TextureProgressBar)

Layers can be negative. A common pattern is:

-1 — parallax backgrounds
0 — world (TileMap, entities, props)
1 — HUD
2 — modal dialogs and pause menus
3 — tooltips and notifications

When the TileMap Itself Sets a z_index

If you set z_index on the TileMap to a large positive value (sometimes done to layer ground tiles above props), this only affects nodes on the same CanvasLayer. It cannot push the TileMap above a different CanvasLayer. A common confusion: developers set TileMap z_index to 100 to overlap entities, then later wonder why their HUD on layer 1 still wins. It always will.

When You Have Multiple HUDs

For a pause menu that should cover the HUD when active, give it a higher layer:

# pause_menu.tscn
PauseMenu (CanvasLayer)
  layer = 2
  process_mode = Node.PROCESS_MODE_ALWAYS   # runs while paused

When the player resumes, set the CanvasLayer’s visible = false — or queue_free it — rather than swapping layers, which would be confusing to maintain.

follow_viewport_enabled and Parallax

CanvasLayer has a follow_viewport_enabled property. With it off (default), the layer ignores the camera entirely — perfect for HUDs. With it on, the layer follows the viewport but with a configurable scale, giving you a fast parallax effect. Keep HUD layers with follow_viewport_enabled = false so they never appear to scroll when the camera moves.

Verifying

Toggle the HUD CanvasLayer’s visibility in the editor. The TileMap should draw normally with it off; the HUD should sit cleanly on top with it on. If the HUD still looks clipped or sandwiched, look for a third CanvasLayer in your scene (sometimes added implicitly by a parent autoload like a transition fader) with a higher layer index.

Understanding the issue

Tilemaps are dense data structures. A single tile change touches several other systems: rendering, collision, possibly navigation. Bugs at the intersection often look like 'I changed one tile, why did three other things break'.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

This bug class disproportionately affects late-stage development. The work to surface it is interactive testing in realistic conditions, which only really happens after the gameplay is in place and assets are populated. Catching it early requires deliberate testing of conditions that look unimportant.

At the engine level, the behavior comes from a deliberate design decision in Godot. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

For shipping games, the safest verification is a staged rollout. Apply the fix to 1% of players for 24 hours; watch the affected metric; expand if green. Skipping the staged rollout means the verification is the entire player base, which is too high a stakes for most fixes.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

There's almost always a less obvious case where the same problem applies. The reported case is the one a player hit; the related cases hide because they're rarer or affect fewer players. After fixing the reported case, search the codebase for the pattern - one fix often unlocks several.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

For shipping titles with a long support window, watch for this issue resurfacing after dependency updates. Engine upgrades, driver updates, OS releases - each one can resurface a bug class you thought you'd fixed because the underlying behavior changed slightly. Regression tests catch the obvious ones; player reports catch the rest.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

Performance implications matter when this bug class scales with player count or asset count. A bug that fires once per session is annoying; a bug that fires once per frame compounds. After fixing, profile the affected code path under realistic load. The fix that's correct for one entity may be too slow for ten thousand.

Diagnostic approach

Diagnosing this class of bug benefits from a structured approach: confirm the symptom, isolate the variables, hypothesize the cause, and verify the hypothesis before writing fix code. Skipping the isolation step is the most common mistake; without it, fixes often address symptoms while the underlying cause continues to produce other variations.

For Godot-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

Modern engine versions ship better tooling for this kind of issue than older versions. If you're on an older release, the diagnostic step may take significantly longer because the tools you'd want don't exist yet. Sometimes the right answer is upgrading rather than fighting through limited tooling.

Within Godot, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Platform-specific edge cases are worth enumerating explicitly. iOS handles backgrounding differently than Android; Windows handles focus changes differently than macOS. A fix that works on the development platform may not work on every target. Test on each shipping platform deliberately.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

Document the fix and its rationale in the commit message or attached engineering doc. Future engineers will encounter related issues; the rationale tells them whether your fix is reusable or specific to the case at hand. Without rationale, the fix gets reverted or copied incorrectly.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Layer beats z_index. z_index beats tree order. Once you internalize that, half your draw-order bugs disappear.”

Adopt the −1/0/1/2/3 layer convention project-wide — future-you will appreciate it.