code wiki / _hdl_build / nx_lagcomp_gate.nx
`nx_lagcomp_gate.nx` source

1// nx_lagcomp_gate.nx -- proves server-side lag compensation (nx_lagcomp): a correctly-aimed action on what the client
2// SAW connects when the server rewinds to that moment, but MISSES if the server naively checks the target's current
3// (already-moved) position. And a genuinely-wrong aim still misses (it's fair adjudication, not auto-hit).
4import "nx_syscalls.nx"
5import "nx_gate_emit_lib.nx"
6import "nx_lagcomp.nx"
7
8func main() -> i64 {
9    g_puts("nx_lagcomp gate (server rewinds history so a catch/hit connects despite RTT, MEASURED)\n" as *u8)
10    var pass: i64 = 0; var total: i64 = 0
11
12    // a target creature moving +2 / server-tick; 1s history ring (60 ticks). now = tick 50.
13    let hist: *i64 = sys_mmap(64*8) as *i64
14    var t: i64 = 0; while t < 64 { hist[t] = t * 2; t = t + 1 }
15    let now: i64 = 50
16    let radius: i64 = 4
17    let cur_pos: i64 = hist[now]                       // target's CURRENT server position = 100
18
19    // the acting client: latency 7 ticks + interpolation delay 5 ticks = sees the target 12 ticks in the past
20    let rewind: i64 = 7 + 5
21    let seen_pos: i64 = lc_rewind(hist, now, rewind)    // hist[38] = 76 -- what the client aimed at
22    let aim: i64 = seen_pos                             // a CORRECT throw at the seen position
23
24    let hit_naive: i64 = lc_hit(aim, cur_pos, radius)                      // server checks current pos -> miss
25    let hit_lagcomp: i64 = lc_hit(aim, lc_rewind(hist, now, rewind), radius) // server rewinds -> connect
26
27    // a genuinely-wrong aim (somewhere the target never was at the seen time) must still miss even with lag comp
28    let bad_hit: i64 = lc_hit(seen_pos + 40, lc_rewind(hist, now, rewind), radius)
29
30    g_puts("  [measure] target now=" as *u8); g_pn(cur_pos); g_puts("  client saw it at=" as *u8); g_pn(seen_pos); g_puts(" (rewind " as *u8); g_pn(rewind); g_puts(" ticks)  aim=" as *u8); g_pn(aim); g_puts("\n" as *u8)
31    g_puts("  [measure] naive (check current pos)=" as *u8); g_pn(hit_naive); g_puts("  lag-compensated (rewind)=" as *u8); g_pn(hit_lagcomp); g_puts("  wrong-aim w/ lagcomp=" as *u8); g_pn(bad_hit); g_puts("\n" as *u8)
32
33    pass = pass + g_check("correct aim CONNECTS with lag compensation (rewind to what the client saw)" as *u8, hit_lagcomp == 1); total=total+1
34    pass = pass + g_check("same aim MISSES without lag comp (target already moved) -- the unfair case lag-comp fixes" as *u8, hit_naive == 0); total=total+1
35    pass = pass + g_check("a genuinely-wrong aim still misses (fair adjudication, not auto-hit)" as *u8, bad_hit == 0); total=total+1
36
37    g_puts("---- lagcomp gate: passed " as *u8); g_pn(pass); g_puts(" / " as *u8); g_pn(total); g_puts(" ----\n" as *u8)
38    if pass == total { g_puts("verdict=GREEN\n" as *u8); sys_exit(0); return 0 }
39    g_puts("verdict=RED\n" as *u8); sys_exit(1); return 1
40}
nx_lagcomp_gate.nx source

`nx_lagcomp_gate.nx` source
