@woosh/meep-engine/src/core/geom/vec/vector_dot_offset.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * N-dimensional dot product over offset slices of two flat buffers.
 *
 *     sum_{i=0..n-1} a[aOff + i] * b[bOff + i]
 *
 * Use when the operands are columns/rows of a flat matrix laid out in a
 * single typed array — passing the buffer plus an offset avoids the header
 * allocation that `.subarray(...)` would incur on every call.
 *
 * @param {number[]|Float32Array|Float64Array} a
 * @param {number} aOff starting index into a
 * @param {number[]|Float32Array|Float64Array} b
 * @param {number} bOff starting index into b
 * @param {number} n number of elements
 * @return {number}
 */
export function vector_dot_offset(a, aOff, b, bOff, n) {
    let result = 0;

    for (let i = 0; i < n; i++) {
        result += a[aOff + i] * b[bOff + i];
    }

    return result;
}