Difference between revisions of "GetPerkInTree UPK mods Enhanced Perk Tree - XCOM:EU 2012"

Latest revision as of 01:04, 16 November 2018

Overview

This page deals with the upk changes modifying the GetPerkInTree functions, which are necessary to fully implement the Enhanced Perk Tree mod

All of these changes are applied to XcomGame.upk

For those who require or prefer the before/after hex blocks, they are here : Before/after hex for GetPerkInTree

Programs and Tools

UE Explorer
ToolBoks v1.20 or greater

Details

There are five separate hex changes necessary to implement this portion of the Enhanced Perk Tree mod.

The PerkInTree functions refer to 'option' and 'branch'

Row corresponds with 'option', and relates to the number of ability icons displayed per rank
Column corresponds with 'branch', and relates to the soldier rank

Rewrite GetPerkInTreeAssault to support up to 44 perk definitions
Rewrite GetPerkInTreeHeavy to support up to 44 perk definitions
Rewrite GetPerkInTreeSniper to support up to 44 perk definitions
Rewrite GetPerkInTreeSupport to support up to 44 perk definitions
Rewrite GetPerkInTreePsi to support up to 16 perk definitions

Support for 11 branches is present in the Class functions, although the initial release only utilizes the first 7 branches Support for 4 options per branch is present in all five functions, although the initial release only utilizes the first 3

These functions all follow a common format.

The branch is selected using a switch/case statement
The option is selected by byte-shifting a four byte integer to select byte 0, 1, 2, or 3.
- byte 0 corresponds to option 0
- byte 1 corresponds to option 1
- byte 2 corresponds to option 2
- byte 3 corresponds to option 3

File Changes

All functions share the following format:

Option *= float(8);
switch(branch)
{
    case 1:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 2:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 3:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 4:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 5:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 6:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 7:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 8:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 9:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 10:
        return((## ## ## ## >> Option) & 0xFF); // numbers are based on perk ID
    
    case 11:
        return (## ## ## ## >> Option) & 0xFF; // numbers are based on perk ID
        
    default:
        return 0
}

GetPerkInTreePsi is identical excepting that the cases only go up to (and including) 4.

'break;' statements are not required because the function always returns after entering a case
The heart of the operation is the (## ## ## ## >> Option) & 0xFF; operation
- ## ## ## ## is a four byte integer value
  - represented in hexadecimal, each 2 digit part represents a perk
    - Ex: 0x00242C30 represents : perk0 = 0x30, perk1 = 0x2C, perk2 = 0x24, perk3 = 0x0
  - represented in decimal, the numbers are jumbled together, but are represented by perk3*2^24 + perk2*2^16 + perk1*2^8 + perk0
    - Ex: perk0 = 0x30 = 48, perk1 = 0x2C = 44, perk2 = 0x24 = 36 results in 36*2^16 + 44*2^8 + 48 = 2,370,608
    - Note that 2,370,608 = 0x242C30
- The >> is the shift-left operator : See wikipedia article [1] for more info
- Option enters the function as the value 0, 1, 2, or 3
  - Option is then multiplied by 8 to become 0, 8, 16 or 24
    - The shift-left operator places the correct byte into bits 0-7
      - The bit-wise AND operator then masks the rest of the 4-byte integer

Hex code replacements compatible with Toolboks' Custom Mod feature will be presented below for each of the five functions.