func Vec3Dist2DSqr(v1, v2 Vec3) float32 {
	dx := v1[0] - v2[0]
	dz := v1[2] - v2[2]
	return dx*dx + dz*dz
}
func Vec3Dist2DSqr(v1, v2 Vec3) float32 {
	dx := v1[0] - v2[0]
	dz := v1[2] - v2[2]
	return dx*dx + dz*dz
}
func Vec3Dist2DSqr ( v1 , v2 Vec3 ) float32 { dx := v1 [ 0 ] - v2 [ 0 ] dz := v1 [ 2 ] - v2 [ 2 ] return dx * dx + dz * dz }
// Vec3Dist2DSqr derives the square of the distance between v1 and v2 on the
// xz-plane.
//
// The vectors are projected onto the xz-plane, so the y-values are ignored.
Vec3Dist2DSqr derives the square of the distance between v1 and v2 on the xz - plane . The vectors are projected onto the xz - plane so the y - values are ignored .