diffuse.rgb *= var_VertexLight; // apply lighting

diffuse.rgb *= var_VertexLight * 2.0; // apply lighting

diffuse.rgb *= light;

#include "wrect.h"

#include "cl_dll.h"

#include <Windows.h>

#include &lt<img src="images/smilies/pp2.gif" border="0" alt="">sapi.h>

#include "FontAwesome.h"

#include "gamemode_gui.h"

#include "subtitles.h"

#include "model_indexes.h"

#include "aim_entity.h"

#include "player_info_window.h"

#include "hl_imgui.h"

extern cl_enginefunc_t gEngfuncs;

extern int isPaused;

extern bool inMainMenu;

SDL_Window *window = NULL;

// To draw imgui on top of Half-Life, we take a detour from certain engine's function into HL_ImGUI_Draw function

void HL_ImGUI_Init() {

  // One of the final steps before drawing a frame is calling SDL_GL_SwapWindow function

  // It must be prevented, so imgui could be drawn before calling SDL_GL_SwapWindow

  // This will hold the constant address of x86 CALL command, which looks like this

  // E8 FF FF FF FF

  // Last 4 bytes specify an offset from this address + 5 bytes of command itself

  unsigned int origin = NULL;

  // We're scanning 1 MB at the beginning of hw.dll for a certain sequence of bytes

  // Based on location of that sequnce, the location of CALL command is calculated

  MODULEINFO module_info;

  if ( GetModuleInformation( GetCurrentProcess(), GetModuleHandle( "hw.dll" ), &module_info, sizeof( module_info ) ) ) {

    origin = ( unsigned int ) module_info.lpBaseOfDll;

    const int MEGABYTE = 1024 * 1024;

    char *slice = new char[MEGABYTE];

    ReadProcessMemory( GetCurrentProcess(), ( const void * ) origin, slice, MEGABYTE, NULL );

    unsigned char magic[] = { 0x8B, 0x4D, 0x08, 0x83, 0xC4, 0x08, 0x89, 0x01, 0x5D, 0xC3, 0x90, 0x90, 0x90, 0x90, 0x90, 0xA1 };

    for ( unsigned int i = 0 ; i < MEGABYTE - 16; i++ ) {

      bool sequenceIsMatching = memcmp( slice + i, magic, 16 ) == 0;

      if ( sequenceIsMatching ) {

        origin += i + 27;

        break;

      }

    }

    delete[] slice;

    char opCode[1];

    ReadProcessMemory( GetCurrentProcess(), ( const void * ) origin, opCode, 1, NULL );

    if ( opCode[0] != 0xFFFFFFE8 ) {

      gEngfuncs.Con_DPrintf( "Failed to embed ImGUI: expected CALL OP CODE, but it wasn't there\n" );

      return;

    }

  } else {

    gEngfuncs.Con_DPrintf( "Failed to embed ImGUI: failed to get hw.dll memory base address\n" );

    return;

  }

  window = SDL_GetWindowFromID( 1 );

  ImGui_ImplSdl_Init( window );

  // To make a detour, an offset to dedicated function must be calculated and then correctly replaced

  unsigned int detourFunctionAddress = ( unsigned int ) &HL_ImGUI_Draw;

  unsigned int offset = ( detourFunctionAddress ) - origin - 5;

  // The resulting offset must be little endian, so

  // 0x0A852BA1 => A1 2B 85 0A

  char offsetBytes[4];

  for ( int i = 0; i < 4; i++ ) {

    offsetBytes[i] = ( offset >> ( i * 8 ) );

  }

  // This is WinAPI call, blatantly overwriting the memory with raw pointer would crash the program

  // Notice the 1 byte offset from the origin

  WriteProcessMemory( GetCurrentProcess(), ( void * ) ( origin + 1 ), offsetBytes, 4, NULL );

  SDL_AddEventWatch( HL_ImGUI_ProcessEvent, NULL );

  ImGuiStyle *style = &ImGui::GetStyle();

  style->AntiAliasedShapes = false;

  style->WindowRounding = 0.0f;

  style->ScrollbarRounding = 0.0f;