Function projectVertices

packages/melonjs/src/math/vertex.ts:71–138

(
	src: Float32Array,
	dst: Float32Array,
	count: number,
	matrix: Float32Array,
	width: number,
	height: number,
	offsetX = 0,
	offsetY = 0,
	zScale = 0,
)

 * @param zScale - scale factor for Z output (0 = don't compute Z)
 */
export function projectVertices(
	src: Float32Array,
	dst: Float32Array,
	count: number,
	matrix: Float32Array,
	width: number,
	height: number,
	offsetX = 0,
	offsetY = 0,
	zScale = 0,
) {
	// hoist all constants out of the loop
	const centerX = width * 0.5 + offsetX;
	const centerY = height * 0.5 + offsetY;
	const negHeight = -height;

	// extract matrix elements once (avoids repeated indexed access)
	const m0 = matrix[0];
	const m1 = matrix[1];
	const m2 = matrix[2];
	const m3 = matrix[3];
	const m4 = matrix[4];
	const m5 = matrix[5];
	const m6 = matrix[6];
	const m7 = matrix[7];
	const m8 = matrix[8];
	const m9 = matrix[9];
	const m10 = matrix[10];
	const m11 = matrix[11];
	const m12 = matrix[12];
	const m13 = matrix[13];
	const m14 = matrix[14];
	const m15 = matrix[15];

	if (zScale !== 0) {
		const negZScale = -zScale;
		for (let i = 0; i < count; i++) {
			const i3 = i * 3;
			const vx = src[i3];
			const vy = src[i3 + 1];
			const vz = src[i3 + 2];

			const tw = m3 * vx + m7 * vy + m11 * vz + m15;
			const invW = tw !== 0 ? 1.0 / tw : 1.0;

			dst[i3] = (m0 * vx + m4 * vy + m8 * vz + m12) * invW * width + centerX;
			dst[i3 + 1] =
				(m1 * vx + m5 * vy + m9 * vz + m13) * invW * negHeight + centerY;
			dst[i3 + 2] = (m2 * vx + m6 * vy + m10 * vz + m14) * invW * negZScale;
		}
	} else {
		// fast path: skip Z computation entirely
		for (let i = 0; i < count; i++) {
			const i3 = i * 3;
			const vx = src[i3];
			const vy = src[i3 + 1];
			const vz = src[i3 + 2];