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

Pure JavaScript game engine. Fully featured and production ready.

/**
 *
 * @param {SMikkTSpaceContext} pContext
 * @param {number[]} tangent
 * @param {number[]} bi_tangent
 * @param {number} fMagS
 * @param {number} fMagT
 * @param {boolean} bi_tangent_preserves_orientation
 * @param {number} iFace
 * @param {number} iVert
 * @returns {void}
 */
export function m_setTSpace(
    pContext,
    tangent,
    bi_tangent,
    fMagS,
    fMagT,
    bi_tangent_preserves_orientation,
    iFace,
    iVert
) {

    // figure out which vertex it is
    const vertex_index = pContext.geometry_buffer_index[iFace * 3 + iVert];

    const tangent_destination = pContext.geometry_buffer_vertex_tangent;
    const tangent_address = vertex_index * 4;

    // for logic explanation, see https://github.com/gltf-rs/mikktspace/blob/6275cc4f15cff8be29819fb34ae8be3b9129dae1/src/lib.rs#L33
    tangent_destination[tangent_address] = tangent[0];
    tangent_destination[tangent_address + 1] = tangent[1];
    tangent_destination[tangent_address + 2] = tangent[2];
    tangent_destination[tangent_address + 3] = bi_tangent_preserves_orientation ? 1 : -1;
}