Overview
The Sweep class creates 3D shapes by sweeping a 2D profile along a 3D path. This powerful technique enables creation of pipes, tubes, rails, and complex extruded forms that follow custom trajectories.
Constructor
const sweep = new Sweep(options?: ISweepOptions);
ISweepOptions
Unique identifier for the sweep. Auto-generated if not provided.
Array of points defining the 3D path along which the profile is swept. Minimum 2 points required.path: [
new Vector3(0, 0, 0),
new Vector3(0, 5, 0),
new Vector3(5, 5, 0),
new Vector3(5, 10, 0)
]
Array of points defining the 2D profile to be swept. Minimum 3 points required. Profile should be defined on a plane perpendicular to the initial path direction.profile: [
new Vector3(-0.5, 0, -0.5),
new Vector3(0.5, 0, -0.5),
new Vector3(0.5, 0, 0.5),
new Vector3(-0.5, 0, 0.5)
]
Hexadecimal color value for the swept shape. Whether to add a cap (face) at the start of the sweep.capStart: true // Close the start
Whether to add a cap (face) at the end of the sweep.capEnd: true // Close the end
Methods
setConfig()
Updates the sweep configuration with path and profile, using default caps (both true).
sweep.setConfig(options: ISweepOptions): void
sweep.setConfig({
path: [
new Vector3(0, 0, 0),
new Vector3(0, 10, 0)
],
profile: [
new Vector3(-1, 0, -1),
new Vector3(1, 0, -1),
new Vector3(1, 0, 1),
new Vector3(-1, 0, 1)
],
color: 0x3498db
});
getBrep()
Returns the B-Rep (Boundary Representation) data as a parsed JSON object.
Example:
const brepData = sweep.getBrep();
console.log('Vertices:', brepData.vertices.length);
console.log('Faces:', brepData.faces.length);
generateGeometry()
Regenerates the THREE.js geometry from the current configuration. Called automatically after setConfig().
sweep.generateGeometry(): void
discardGeometry()
Disposes of the current geometry to free memory.
sweep.discardGeometry(): void
Properties
Unique identifier for the sweep instance.
Current sweep configuration including path, profile, color, and cap settings.const pathLength = sweep.options.path.length;
const profilePoints = sweep.options.profile.length;
Get or set the sweep color.sweep.color = 0xff0000; // Change to red
Enable or disable outline rendering for the sweep edges.sweep.outline = true; // Show wireframe
sweep.outline = false; // Hide wireframe
Usage Examples
Simple Pipe
import { Sweep, Vector3 } from 'opengeometry-three';
// Straight vertical pipe with square cross-section
const pipe = new Sweep({
path: [
new Vector3(0, 0, 0),
new Vector3(0, 10, 0)
],
profile: [
new Vector3(-0.5, 0, -0.5),
new Vector3(0.5, 0, -0.5),
new Vector3(0.5, 0, 0.5),
new Vector3(-0.5, 0, 0.5)
],
color: 0x2ecc71,
capStart: true,
capEnd: true
});
scene.add(pipe);
Curved Tube
import { Sweep, Vector3 } from 'opengeometry-three';
// Create a curved path
const curvedPath = [];
for (let i = 0; i <= 20; i++) {
const t = i / 20;
curvedPath.push(new Vector3(
Math.cos(t * Math.PI) * 5,
t * 10,
Math.sin(t * Math.PI) * 5
));
}
// Circular profile
const circularProfile = [];
const segments = 12;
for (let i = 0; i < segments; i++) {
const angle = (i / segments) * Math.PI * 2;
circularProfile.push(new Vector3(
Math.cos(angle) * 0.5,
0,
Math.sin(angle) * 0.5
));
}
const tube = new Sweep({
path: curvedPath,
profile: circularProfile,
color: 0x3498db,
capStart: true,
capEnd: true
});
tube.outline = true;
Handrail
import { Sweep, Vector3 } from 'opengeometry-three';
// Staircase handrail path
const handrailPath = [
new Vector3(0, 0, 0),
new Vector3(0, 2, 2),
new Vector3(0, 4, 4),
new Vector3(0, 6, 6),
new Vector3(0, 8, 8)
];
// Circular handrail profile
const handrailProfile = [];
for (let i = 0; i < 16; i++) {
const angle = (i / 16) * Math.PI * 2;
handrailProfile.push(new Vector3(
Math.cos(angle) * 0.3,
0,
Math.sin(angle) * 0.3
));
}
const handrail = new Sweep({
path: handrailPath,
profile: handrailProfile,
color: 0x8b4513,
capStart: true,
capEnd: true
});
Open-Ended Sweep
import { Sweep, Vector3 } from 'opengeometry-three';
// Sweep without end caps (open tube)
const openTube = new Sweep({
path: [
new Vector3(0, 0, 0),
new Vector3(5, 0, 0),
new Vector3(5, 5, 0)
],
profile: [
new Vector3(-0.5, 0, -0.5),
new Vector3(0.5, 0, -0.5),
new Vector3(0.5, 0, 0.5),
new Vector3(-0.5, 0, 0.5)
],
color: 0xe74c3c,
capStart: false, // No start cap
capEnd: false // No end cap
});
Architectural Molding
import { Sweep, Vector3 } from 'opengeometry-three';
// Complex profile for decorative molding
const moldingProfile = [
new Vector3(0, 0, 0),
new Vector3(0.2, 0, 0.1),
new Vector3(0.3, 0, 0.1),
new Vector3(0.4, 0, 0.3),
new Vector3(0.5, 0, 0.3),
new Vector3(0.6, 0, 0)
];
// Path around a room corner
const roomPath = [
new Vector3(0, 8, 0),
new Vector3(10, 8, 0),
new Vector3(10, 8, 10)
];
const molding = new Sweep({
path: roomPath,
profile: moldingProfile,
color: 0xf5f5dc,
capStart: false,
capEnd: false
});
Implementation Details
Sweep Algorithm
The sweep operation positions the profile at each path point and connects adjacent profiles:
Rust Implementation: /workspace/source/main/opengeometry/src/primitives/sweep.rs:92-99
let options = SweepOptions {
cap_start: self.cap_start,
cap_end: self.cap_end,
};
self.brep = sweep_profile_along_path(&self.path_points, &self.profile_points, options);
Material Configuration
Sweeps use MeshStandardMaterial with transparency:
Source: /workspace/source/main/opengeometry-three/src/shapes/sweep.ts:123-127
const material = new THREE.MeshStandardMaterial({
color: this.options.color,
transparent: true,
opacity: 0.6,
});
Validation
The sweep validates path and profile requirements:
Source: /workspace/source/main/opengeometry-three/src/shapes/sweep.ts:75-87
validateOptions() {
if (!this.options) {
throw new Error("Options are not defined for Sweep");
}
if (this.options.path.length < 2) {
throw new Error("Sweep path requires at least 2 points.");
}
if (this.options.profile.length < 3) {
throw new Error("Sweep profile requires at least 3 points.");
}
}
Cap Generation
When capStart or capEnd is true, the sweep operation adds triangulated faces at the ends:
Source: /workspace/source/main/opengeometry-three/src/shapes/sweep.ts:95-96
Best Practices
Profile Orientation: Define the profile on a plane perpendicular to the initial path direction. For paths starting along the Y-axis, define profiles on the XZ plane.
Path Smoothness: Sharp angles in the path may cause geometry artifacts. For smoother results, use more path points with gradual direction changes.
Profile Complexity: Complex profiles with many points will generate more geometry. Balance profile detail with performance requirements.
Closed Profiles: For hollow tubes, ensure the profile forms a closed loop by making the first and last points identical.
Vertex Count
Total vertices ≈ path_points × profile_points
Face Count
Total faces ≈ (path_points - 1) × profile_points × 2 + cap_faces
Optimization Tips
- Reduce Path Points: Use fewer points for distant or less important sweeps
- Simplify Profiles: Use simpler profiles (fewer vertices) when high detail isn’t needed
- Disable Caps: Set
capStart and capEnd to false for open-ended shapes
- Outline Toggle: Only enable outlines when needed for debugging or emphasis
See Also
- Cylinder - For simple straight extrusions
- Polygon - For creating custom 2D profiles
- Cuboid - For rectangular extrusions
