# Improve a generated 3D scene with a screenshot and critic agent loop

> A creator built a rainy neon city as a single 52 KB HTML file on WebGPU in about 40 minutes, and credits the quality jump to a loop where Claude screenshots its own render and a fresh critic agent reviews it.

- URL: https://paperchasewebb.ai/bots/marketplace/items/improve-a-generated-3d-scene-with-a-screenshot-and-critic-agent-loop/
- Type: Agent use case pack
- Category: Vibe coding
- By: PaperChaseWebb
- Works with: Claude Code (named in the listing); Plain .md
- Price: Free USD
- Difficulty: Beginner
- Setup time: 15 min
- Time to result: One working session
- Format: Markdown (.md) file, improve-a-generated-3d-scene-with-a-screenshot-and-critic-agent-loop.md
- Version: 1.0, updated 2026-10-25
- License: Personal and commercial use. Credit the original source when you share the workflow.

## What you end up with

The key detail is that the critic is a separate, fresh agent, so it judges the image instead of defending its own code.

## What you get

- A plain-language summary of the workflow
- A fill-in prompt template
- What to watch out for
- A link to the original source

## Who it is for

Builders who already use AI agents and want a proven workflow they can copy into their own project.

## Tools needed

- Claude Code (Opus 5.5): writes the scene
- Fresh critic agent: reviews screenshots with no attachment to the code
- WebGPU: rendering, with no engine or libraries
- You need: An AI coding agent or chat model
- You need: A small real task to try it on

Cost to run: Free with the agent plan you already use.

## How it works

1. **Have the agent build the first version.** Have the agent build the first version. Expected: Done before you move to the next step.
2. **Have it take a screenshot of the running result.** Have it take a screenshot of the running result. Expected: Done before you move to the next step.
3. **Start a fresh agent, show it only the screenshot and the goal, and ask.** Start a fresh agent, show it only the screenshot and the goal, and ask for a blunt critique. Expected: Done before you move to the next step.
4. **Feed the critique back to the builder and repeat two or three times.** Feed the critique back to the builder and repeat two or three times. Expected: Done before you move to the next step.

## Sample prompt: Workflow template (Claude Code (Opus 5.5), Fresh critic agent)

```
Apply this workflow to [your project]:
1. Have the agent build the first version.
2. Have it take a screenshot of the running result.
3. Start a fresh agent, show it only the screenshot and the goal, and ask for a blunt critique.
4. Feed the critique back to the builder and repeat two or three times.
Stop and ask me before anything irreversible: deploys, payments, sends or deletes.
```

Adapted by PaperChaseWebb. Not the original author's prompt.

## Free preview of improve-a-generated-3d-scene-with-a-screenshot-and-critic-agent-loop.md

````markdown
# Improve a generated 3D scene with a screenshot and critic agent loop

PaperChase agent use case (free feed entry), version 1.0. Source: [@SKatalystAI (Sinda) on X](https://x.com/SKatalystAI/status/2111809289442435225), 2026-10-18.

## What they did

One prompt produced a first version, then three rounds of screenshot, critique and revise took it from what the creator rated 2 out of 10 to a moody night scene.

## Worth knowing

The key detail is that the critic is a separate, fresh agent, so it judges the image instead of defending its own code. The same loop works for UI, game art and landing pages. Ratings are the creator's own.
````

## Worth knowing

- The key detail is that the critic is a separate, fresh agent, so it judges the image instead of defending its own code. The same loop works for UI, game art and landing pages. Ratings are the creator's own.
- Figures are as reported by the original author and were not re-measured by us.

## Questions

**Where does this come from?** A public post credited to @SKatalystAI (Sinda) on X. Source: https://x.com/SKatalystAI/status/2111809289442435225

**Is it free?** Yes. Feed entries are free to read and download.

## How to get it

Free sample. Download it directly at https://paperchasewebb.ai/bots/marketplace/items/improve-a-generated-3d-scene-with-a-screenshot-and-critic-agent-loop/, no signup.

Seller: PaperChaseWebb Inc., mgmt@paperchasewebb.com