# 3D Scene and Render Pass Preview

> Light a Kerfwise concept and inspect beauty, color, normals, depth and object IDs. Render a small deterministic SVG preview from a Form Studio project or Render Desk recipe. Download the preview and editable recipe, then continue locally in Kerfwise with higher resolution and sampling.

Part of usefulweb.app (https://usefulweb.app/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://kerfwisescenepreview.usefulweb.app/ (interactive tool at https://kerfwisescenepreview.usefulweb.app/tool)
- JSON API: POST https://kerfwisescenepreview.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://kerfwisescenepreview.usefulweb.app/api/v1/tool)
- OpenAPI: https://kerfwisescenepreview.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://kerfwisescenepreview.usefulweb.app/mcp - tool `kerfwise_scene_preview`

## Inputs
- project (textarea): Form project or render recipe JSON
- width (number): Preview width (px)
- height (number): Preview height (px)
- samples (number): Samples per pixel
- pass (select): Render pass

## Method
- Independent concept renderer for Kerfwise extrusions. It uses orthographic camera rays, direct light with sampled soft shadows, short-range ambient occlusion and one metal reflection. It does not run MoonRay or import its scenes.
- Coordinates are millimetres, Z up. Hidden solids are excluded. Source colors are decoded from sRGB for lighting; the beauty pass returns display sRGB. Normal, depth and object-ID passes are display diagnostics, not EXR or Cryptomatte.
- Seeds and sample positions are deterministic. API previews allow 32–128 pixels per side and 1–4 samples, at most 65536 pixel samples. Render Desk supports larger local previews, at most 4096 visible triangles, 384000 pixels and 6 million pixel samples.

## Limits
- Concept previews only. No MoonRay execution, scene import, unbiased path tracing or EXR output.