q3_railgun_patch

change_cooldown.py will help you change q3 railgun cooldown time without recompiling qagame.qvm.

usage

python3 change_cooldown.py /path/to/vm/qagame.qvm "${NEW_TIME_IN_MS}"

or

python3 change_cooldown.py /path/to/vm/qagame.qvm "${NEW_TIME_IN_MS}" "${OLD_TIME_IN_MS}"

OLD_TIME_IN_MS is 1500 by default (as in the original Q3A game).

disclaimer

Please respect copyrights. Remember, if you patching binaries without source code and/or proprietary, law-protected - author has nothing to do with it.

implementation details

• patch target translation unit: code/game/bg_pmove.c, function: PM_Weapon

• patch target code:

  • https://github.com/ioquake/ioq3/blob/3fb9006e6461b877b67781cd0f0d94032804a475/code/game/bg_pmove.c#L1669
  • https://github.com/id-Software/Quake-III-Arena/blob/dbe4ddb10315479fc00086f08e25d968b4b43c49/code/game/bg_pmove.c#L1670

  case WP_PLASMAGUN:
    addTime = 100;
    break;
  
  case WP_RAILGUN:
    addTime = 1500; /* <-- we need to change this */
    break;
  
  case WP_BFG:
    addTime = 200;
    break;

• qvm binary pattern (generated via ioquake3 assembler)

  0000 2008 1621 0100 0a09 0c00 0000 08 ; prefix
  dc 05 ; <-- we need to change this
  00 0020 0816 2101 000a 090c 0000 0008 ; suffix
  

• qvm assembler code:

  LABELV $619
  ADDRLP4 0
  CNSTI4 100
  ASGNI4
  ADDRGP4 $611
  JUMPV
  
  LABELV $620
  ADDRLP4 0
  CNSTI4 1500 ; <-- we need to change this
  ASGNI4
  ADDRGP4 $611
  JUMPV
  
  LABELV $621
  ADDRLP4 0
  CNSTI4 200
  ASGNI4
  ADDRGP4 $611
  JUMPV