Mesh & visualization

Tools for converting B-rep bodies into triangle meshes, decimating those meshes, rendering headless PNG previews of the scene, ray-casting a pixel back to a world-space surface point, and producing multi-view ISO 128-30 DXF technical drawings. Reach for this family when you need a visual snapshot, a lightweight mesh export, or a production drawing.

Tools

generate_mesh · simplify_mesh · render_preview · pick_surface_point · generate_drawing

generate_mesh

Tessellate a scene body into triangles and return quality metrics; optionally write the mesh to .stl or .obj.

Server: Swift + Node

Parameters

Returns — Quality metrics (triangle count, min/max edge length, etc.). If outputPath is given, the mesh file is written. If returnGeometry is true, vertex + triangle data is included in the response.

Example

// tool call arguments
{ "bodyId": "part", "linearDeflection": 0.1, "outputPath": "/tmp/part.stl" }

// example result
{
  "triangleCount": 1248,
  "minEdgeLength": 0.08,
  "maxEdgeLength": 3.4,
  "outputPath": "/tmp/part.stl"
}

Drives — OCCTSwiftMesh tessellation pipeline; OCCTSwift BREP → mesh bridge.

simplify_mesh

QEM mesh decimation via OCCTSwiftMesh (vendored meshoptimizer). Outputs .stl or .obj.

Server: Swift + Node

Parameters

Returns — Triangle count before and after, achieved Hausdorff distance, and the written outputPath.

Example

// tool call arguments
{
  "bodyId": "housing",
  "outputPath": "/tmp/housing_lod.obj",
  "targetReduction": 0.7,
  "preserveBoundary": true
}

// example result
{
  "inputTriangles": 8400,
  "outputTriangles": 2520,
  "hausdorffDistance": 0.22,
  "outputPath": "/tmp/housing_lod.obj"
}

Drives — OCCTSwiftMesh QEM decimator (meshoptimizer).

render_preview

Headless Metal render of the current scene (or a named subset of bodies) to a PNG file. Overlays sidecar annotations (dimensions, primitives, bounding boxes, diff markers) and renders measurement labels.

Server: Swift + Node

Parameters

Returns — Path to the written PNG and image dimensions. Returns an error if the scene is empty or Metal is unavailable.

Example

// tool call arguments
{
  "outputPath": "/tmp/preview.png",
  "options": {
    "camera": "iso",
    "displayMode": "shadedWithEdges",
    "background": "light",
    "width": 1200,
    "height": 900
  }
}

// example result
{
  "outputPath": "/tmp/preview.png",
  "width": 1200,
  "height": 900
}

Notes — Pass the same options.camera / width / height values to pick_surface_point so pixel coordinates map to the same ray. Annotation overlays read from annotations.json in the output directory.

Drives — OCCTSwiftViewport OffscreenRenderer; OCCTSwiftTools Shape → ViewportBody bridge; AnnotationsRenderer for sidecar overlays.

pick_surface_point

Cast a ray through pixel (screenX, screenY) of a render_preview-framed view and return the nearest world-space surface point on a body, plus the bodyId and a selectionId.

Server: Swift only

Parameters

Returns — World-space point [x, y, z], bodyId, and selectionId. The selectionId is a valid anchor for add_dimension, enabling you to measure to an arbitrary surface point rather than a topology centroid.

Example

// tool call arguments
{
  "screenX": 612,
  "screenY": 480,
  "options": { "camera": "iso", "width": 1200, "height": 900 }
}

// example result
{
  "point": [12.4, 0.0, 8.7],
  "bodyId": "part",
  "selectionId": "sel:part#surfacePoint[0]"
}

Notes — Always pass the same options that were used in the preceding render_preview call; mismatched framing will produce incorrect world coordinates. The returned selectionId can be passed directly to add_dimension as an anchor.

generate_drawing

Render a multi-view ISO 128-30 DXF technical drawing. Pass bodyId for a single-part drawing with sections and dimensions, or bodyIds (two or more bodies) for a general-arrangement assembly sheet with a parts list and numbered balloons.

Server: Swift + Node

Parameters

Returns — Path to the written .dxf file and a summary of views generated. Returns an error if neither bodyId nor bodyIds resolves to a loaded body.

Example

// tool call arguments
{
  "bodyId": "bracket",
  "outputPath": "/tmp/bracket.dxf",
  "spec": {
    "sheet": "A3",
    "title": "Bracket — Rev A",
    "views": ["front", "top", "right", "iso"]
  }
}

// example result
{
  "outputPath": "/tmp/bracket.dxf",
  "views": ["front", "top", "right", "iso"],
  "bodyCount": 1
}

Notes — For assembly sheets (bodyIds), per-view sections and dimensions in the spec are ignored; the sheet receives a shared multi-body view with an auto-generated parts list and one balloon per body. bodyIds takes precedence over bodyId when both are supplied.

Drives — DrawingComposer (from OCCTSwiftScripts); ISO 128-30 projection engine in OCCTSwift.