Solids & Components

Unlike static 3D models, solids are generated from code every time their parameters change. Define a foundation with width, depth, and height parameters, then adjust those values to resize the foundation instantly. The same solid definition can be instanced multiple times with different parameter values.

Each solid's code is organized into blueprints and parts:

Solids render in two modes depending on context:

• Scene mode (Cesium) — Solids appear on the globe using GPU-instanced mesh rendering. Efficient even with many identical objects.
• Local space mode (Three.js) — When you edit a solid, the viewport switches to a detailed Three.js view with construction geometry, live preview, and camera controls for inspecting your shape up close.

A simple foundation slab with three parameters:

// Part: "Foundation"
const { width, depth, height } = params;
return box(width, depth, height);

The params object contains all declared parameter values. Replicad functions like box(), cylinder(), sphere(), and sketchRectangle() are available globally in the sandbox.

Return an object or array to apply materials to your shapes:

// Color material
return { shape: cylinder(1, 2), color: '#8B4513', roughness: 0.8 };

// Texture with tint
return { shape: base, texture: 'concrete', textureScale: 2, color: '#ddccbb' };

// Multiple shapes with different materials
return [
  { shape: trunk, color: '#8B4513' },
  { shape: foliage, color: '#228B22CC' },  // alpha = transparency
];

Add reference lines and planes that appear during editing but don't render in the final scene:

// Show a reference axis
showLine([[0, 0, 0], [0, 0, params.height]], '#ff0');

// Show a reference plane
showPlane([[0, 0, 0], [w, 0, 0], [w, d, 0], [0, d, 0]], [0, 0, 1], '#0af');

Export semantic geometry that operations and other systems can query:

featurePoint('ground', [5, 4, 0]);       // A named point
featureLine('ridge', [[0,0,3], [10,0,3]]); // A named polyline
featureLoop('perimeter', [...corners]);    // A closed loop
featurePlane('base', [0,0,0], [0,0,1]);   // Origin + normal

Multiple features can share the same name — for example, several 'ground' points marking ground level around a foundation perimeter.

Solids can be exported to STEP format (.step / .stp) for interop with CAD software like AutoCAD, SolidWorks, Fusion 360, and FreeCAD. Use the export dialog in the editor to download a solid as a STEP file.

When you assign a dimension to a number parameter, SiteCAD displays the value in the user's preferred unit and converts to the base unit internally.

A component is a container that groups other entities — solids, traces, boundaries, or even nested components. The site root (Entity 0) is itself a component.

• Grouping — Moving a component moves all its children together.
• Parameters — Components can declare their own parameters that child entities bind to, creating a configurable assembly.
• Nesting — Components can contain other components, building up complex hierarchies (e.g., a "Farm" component containing "Barn" and "Silo" components).

An instance is a reference to a component (or solid) that inherits its structure. Instances share the prototype's entities but can override declared parameters.

• Prototype link — Change the prototype once and all instances update automatically.
• Parameter overrides — Each instance can customize parameter values without affecting the prototype or other instances.
• Efficient — Instances don't duplicate geometry data. The renderer uses GPU instancing for identical shapes.