import { Vector3 } from '@math.gl/core';
import { GL } from "../constants.js";
import { assert } from "../utils/assert.js";
import { makePrimitiveIterator } from "../iterators/primitive-iterator.js";
import { getPrimitiveModeType } from "../primitives/modes.js";
import { getPositions } from "./get-attribute-from-geometry.js";
/**
 * Computes vertex normals for a geometry
 * @param param0
 * @returns
 */
// eslint-disable-next-line max-statements
export function computeVertexNormals(geometry) {
    // Only support GL.TRIANGLES, GL.TRIANGLE_STRIP, GL.TRIANGLE_FAN
    assert(getPrimitiveModeType(geometry.mode) === GL.TRIANGLES, 'TRIANGLES required');
    const { values: positions } = getPositions(geometry);
    const normals = new Float32Array(positions.length);
    const vectorA = new Vector3();
    const vectorB = new Vector3();
    const vectorC = new Vector3();
    const vectorCB = new Vector3();
    const vectorAB = new Vector3();
    for (const primitive of makePrimitiveIterator(geometry)) {
        vectorA.fromArray(positions, primitive.i1 * 3);
        vectorB.fromArray(positions, primitive.i2 * 3 + 3);
        vectorC.fromArray(positions, primitive.i3 * 3 + 6);
        vectorCB.subVectors(vectorC, vectorB);
        vectorAB.subVectors(vectorA, vectorB);
        const normal = vectorCB.cross(vectorAB);
        normal.normalize();
        // @ts-ignore
        const { primitiveIndex } = primitive;
        normals[primitiveIndex * 9 + 0] = normal.x;
        normals[primitiveIndex * 9 + 1] = normal.y;
        normals[primitiveIndex * 9 + 2] = normal.z;
        normals[primitiveIndex * 9 + 3] = normal.x;
        normals[primitiveIndex * 9 + 4] = normal.y;
        normals[primitiveIndex * 9 + 5] = normal.z;
        normals[primitiveIndex * 9 + 6] = normal.x;
        normals[primitiveIndex * 9 + 7] = normal.y;
        normals[primitiveIndex * 9 + 8] = normal.z;
    }
    return normals;
}