@woosh/meep-engine/src/engine/graphics/geometry/MikkT/buffer_geometry_generate_tangents.js

Pure JavaScript game engine. Fully featured and production ready.

import { BufferAttribute } from "three";
import { genTangSpace, SMikkTSpaceContext } from "./MikkTSpace.js";

/**
 * only works with indexed geometries
 * @param {THREE.BufferGeometry} geo
 */
export function buffer_geometry_generate_tangents(geo) {

    const attribute_position = geo.getAttribute('position');

    if (geo.getAttribute('tangent') === undefined) {
        geo.setAttribute('tangent', new BufferAttribute(new Float32Array(attribute_position.count * 4), 4, false));
    }

    const attribute_tangent = geo.getAttribute('tangent');


    const ctx = new SMikkTSpaceContext();

    ctx.geometry_buffer_index = geo.getIndex().array;
    ctx.geometry_buffer_vertex_position = attribute_position.array;
    ctx.geometry_buffer_vertex_normal = geo.getAttribute('normal').array;
    ctx.geometry_buffer_vertex_uv = geo.getAttribute('uv').array;
    ctx.geometry_buffer_vertex_tangent = attribute_tangent.array;

    genTangSpace(ctx);
}