Visual Feedback — Seeing Your Scene

The screenshot tool lets you capture what the Decentraland preview looks like right now. The browser stays open between calls — only the first screenshot takes ~15s (launch + enter scene). After that, screenshots are instant.

Prerequisites: The preview server must be running (/preview). The tool auto-detects the preview URL.

When to Use Screenshots

• After completing code changes — verify the final result looks correct
• When the user asks "how does it look?" — show them and describe what you see
• When debugging visual issues — "the tree is invisible" → screenshot to see what's actually rendering

Do NOT use screenshots to explore or navigate the scene. Make all code changes first, then take 1-2 screenshots to verify.

Basic Usage

Take a screenshot of the current view:

Use the screenshot tool with no actions to capture the current scene view.

The tool returns the image directly — you'll see it and can describe what's visible.

Movement & Camera

The scene camera always faces north in headless mode. Movement is relative to compass direction, not camera:

Action	Direction	Key
moveForward	North (toward top of screen)	W
moveBack	South (toward bottom)	S
moveRight	East (toward right)	D
moveLeft	West (toward left)	A

Movement speed is ~6 meters/second. Default holdMs is 300ms (~1.8 meters).

Camera rotation

Use look actions to rotate the camera view (arrow key holds):

Action	Effect
lookLeft	Rotate camera left
lookRight	Rotate camera right
lookUp	Tilt camera up
lookDown	Tilt camera down

Default rotation hold is 300ms. Use holdMs for more or less rotation.

Interacting Before Capture

Click on objects

screenshot with actions:
1. click (x: 640, y: 400) — click center of viewport
→ captures the result (e.g., object selected, door opened)

Coordinates are in pixels (viewport is 1280×720).

Press keys

screenshot with actions:
1. key (key: "1") — toggle editor camera
2. wait (ms: 500) — let camera settle
→ captures the overhead editor view

Workflow

1. Make all code changes (write to src/index.ts)
2. Take one screenshot with wait: 2000 to let hot-reload settle
3. Evaluate — describe honestly: what works, what's wrong
4. Fix if needed — then take one more screenshot to confirm

Keep it to 1-2 screenshots per task. Each screenshot consumes significant tokens.

Scene Layout Awareness

• Each parcel is 16×16 meters. A 1×1 scene has coordinates 0-16 in X and Z.
• Y is up. Ground level is Y=0.
• The avatar spawns near the south-west corner (low X, low Z).
• Objects at the center of a 1×1 scene are at roughly (8, 0, 8).

WARNING: If you see empty/gray space, "No scene", or no content — you've walked outside the scene boundaries. STOP moving. Keep movements small (holdMs: 300).

Troubleshooting

Problem	Solution
Screenshot shows welcome screen	The scene hasn't loaded yet — increase wait time
Black/empty screenshot	Preview server may have crashed — check /tasks
Objects not visible	They may be behind the camera (south of avatar) — use moveBack or lookLeft/lookRight to find them
Scene looks different after code change	Hot reload takes ~1-2s — add a wait action of 2000ms
"No preview server running"	Start it with /preview first
Empty/gray space, no scene content	You've left the scene boundaries — stop moving

Tips

• First screenshot is slow (~15s) because it launches a browser and enters the scene. After that, screenshots are instant.
• The browser persists across all screenshot calls in the session — no repeated logins.
• Keep movements small — use holdMs: 300 (default) to avoid walking out of the scene.
• Hot reload — after writing code, wait ~2s before screenshotting to let the scene update.
• Describe honestly — if something looks wrong, say so. The user trusts your visual assessment.