three-mesh-bvh
Version:
A BVH implementation to speed up raycasting against three.js meshes.
148 lines (113 loc) • 4.19 kB
JavaScript
/** @import { BufferGeometry } from 'three' */
import { Vector2, Vector3, Triangle } from 'three';
// sets the vertices of triangle `tri` with the 3 vertices after i
export function setTriangle( tri, i, index, pos ) {
const ta = tri.a;
const tb = tri.b;
const tc = tri.c;
let i0 = i;
let i1 = i + 1;
let i2 = i + 2;
if ( index ) {
i0 = index.getX( i0 );
i1 = index.getX( i1 );
i2 = index.getX( i2 );
}
ta.x = pos.getX( i0 );
ta.y = pos.getY( i0 );
ta.z = pos.getZ( i0 );
tb.x = pos.getX( i1 );
tb.y = pos.getY( i1 );
tb.z = pos.getZ( i1 );
tc.x = pos.getX( i2 );
tc.y = pos.getY( i2 );
tc.z = pos.getZ( i2 );
}
const tempV1 = /* @__PURE__ */ new Vector3();
const tempV2 = /* @__PURE__ */ new Vector3();
const tempV3 = /* @__PURE__ */ new Vector3();
const tempUV1 = /* @__PURE__ */ new Vector2();
const tempUV2 = /* @__PURE__ */ new Vector2();
const tempUV3 = /* @__PURE__ */ new Vector2();
/**
* @typedef {Object} HitTriangleInfo
* @property {{ a: number, b: number, c: number, materialIndex: number, normal: Vector3 }} face
* Triangle vertex indices, material index, and face normal.
* @property {Vector2|null} uv - UV coordinates at the hit point, or `null` if no UV attribute is present.
* @property {Vector3} barycoord - Barycentric coordinates of the hit point within the triangle.
*/
/**
* Computes hit-point information for a point on a triangle within a `BufferGeometry`. Returns
* the face vertex indices, face normal, material index, UV coordinates, and barycentric coordinates.
* Useful for retrieving detailed hit data after a call to `MeshBVH.closestPointToPoint` or
* `MeshBVH.closestPointToGeometry`.
*
* @section Functions
* @param {Vector3} point - The point on the triangle surface (in the geometry's local space).
* @param {BufferGeometry} geometry - The geometry containing the triangle.
* @param {number} triangleIndex - The index of the triangle within the geometry.
* @param {HitTriangleInfo} [target] - Optional object to write results into. Reuses existing
* `face`, `uv`, and `barycoord` sub-objects if present.
* @returns {HitTriangleInfo}
*/
export function getTriangleHitPointInfo( point, geometry, triangleIndex, target ) {
const indices = geometry.getIndex().array;
const positions = geometry.getAttribute( 'position' );
const uvs = geometry.getAttribute( 'uv' );
const a = indices[ triangleIndex * 3 ];
const b = indices[ triangleIndex * 3 + 1 ];
const c = indices[ triangleIndex * 3 + 2 ];
tempV1.fromBufferAttribute( positions, a );
tempV2.fromBufferAttribute( positions, b );
tempV3.fromBufferAttribute( positions, c );
// find the associated material index
let materialIndex = 0;
const groups = geometry.groups;
const firstVertexIndex = triangleIndex * 3;
for ( let i = 0, l = groups.length; i < l; i ++ ) {
const group = groups[ i ];
const { start, count } = group;
if ( firstVertexIndex >= start && firstVertexIndex < start + count ) {
materialIndex = group.materialIndex;
break;
}
}
// extract barycoord
const barycoord = target && target.barycoord ? target.barycoord : new Vector3();
Triangle.getBarycoord( point, tempV1, tempV2, tempV3, barycoord );
// extract uvs
let uv = null;
if ( uvs ) {
tempUV1.fromBufferAttribute( uvs, a );
tempUV2.fromBufferAttribute( uvs, b );
tempUV3.fromBufferAttribute( uvs, c );
if ( target && target.uv ) uv = target.uv;
else uv = new Vector2();
Triangle.getInterpolation( point, tempV1, tempV2, tempV3, tempUV1, tempUV2, tempUV3, uv );
}
// adjust the provided target or create a new one
if ( target ) {
if ( ! target.face ) target.face = { };
target.face.a = a;
target.face.b = b;
target.face.c = c;
target.face.materialIndex = materialIndex;
if ( ! target.face.normal ) target.face.normal = new Vector3();
Triangle.getNormal( tempV1, tempV2, tempV3, target.face.normal );
if ( uv ) target.uv = uv;
target.barycoord = barycoord;
return target;
} else {
return {
face: {
a: a,
b: b,
c: c,
materialIndex: materialIndex,
normal: Triangle.getNormal( tempV1, tempV2, tempV3, new Vector3() )
},
uv: uv,
barycoord: barycoord,
};
}
}