LCCObject::setClipPrism

Sets a polygonal prism clipping region.

Defines a prism volume by extruding a set of coplanar polygon vertices along the face normal direction using offsetMin / offsetMax, and clips the scene accordingly. Supports both convex and concave polygons; self-intersecting polygons are not supported.

Pass undefined or omit the parameter to clear the clipping.

Version Requirement

SDK v0.6.4+

Engine Support

Three.js

API

LCCObject::setClipPrism(param?: LccClipPrismParams): void

Parameters

LccClipPrismParams

Parameter	Type	Required	Default	Description
`vertices`	`IPoint3[]`	Yes	-	Reference plane polygon vertices (world coordinates, coplanar, any winding order). Min 3, max 200.
`offsetMax`	`number`	Yes	-	Upper offset along the face normal direction (can be negative, must be greater than `offsetMin`).
`offsetMin`	`number`	Yes	-	Lower offset along the face normal direction (can be negative, must be less than `offsetMax`).
`normal`	`IPoint3`	Yes	-	Normal direction.
`clipSide`	`number`	No	`1`	Clipping mode: `1` = keep interior (clip exterior), `-1` = keep exterior (clip interior).

IPoint3

interface IPoint3 {
    x: number;
    y: number;
    z: number;
}

Return Value

void

Usage Example

// Set a rectangular prism clipping region (4 coplanar vertices)
lccObject.setClipPrism({
    vertices: [
        { x: 0, y: 0, z: 0 },
        { x: 10, y: 0, z: 0 },
        { x: 10, y: 10, z: 0 },
        { x: 0, y: 10, z: 0 }
    ],
    offsetMin: -5,
    offsetMax: 5,
    normal: { x: 0, y: 0, z: 1 },
    clipSide: 1
});

// Inverse clipping: keep the exterior of the prism
lccObject.setClipPrism({
    vertices: [
        { x: 0, y: 0, z: 0 },
        { x: 10, y: 0, z: 0 },
        { x: 10, y: 10, z: 0 },
        { x: 0, y: 10, z: 0 }
    ],
    offsetMin: -5,
    offsetMax: 5,
    normal: { x: 0, y: 0, z: 1 },
    clipSide: -1
});

// Clear clipping
lccObject.setClipPrism();

Notes

Vertices must be coplanar (tolerance: 0.01 world coordinate units). Non-coplanar vertices will cause the call to fail with an error log.
The vertex count must be between 3 and 200. Values outside this range will cause the call to fail.
offsetMax must be strictly greater than offsetMin; otherwise the call will fail.
Adjusting offsetMin / offsetMax / clipSide is a lightweight operation and can be called at high frequency.
Modifying polygon vertices triggers an internal texture update, so frequent vertex updates are not recommended.
Self-intersecting polygons are not supported; using them will produce unpredictable clipping results.