Grand Theft Auto IV - RTX Remix Compatibility Mod

Made specifically for NVIDIA's RTX Remix.
Compatible with Grand Theft Auto IV: The Complete Edition (1.2.0.59)

If you want to support my work,
consider buying me a Coffee or by becoming a Patreon

Feel free to join the discord server: https://discord.gg/FMnfhpfZy9

Table of Contents

Overview
Installing
Uninstalling
Usage
Compiling

Overview

First and foremost, this is not a remaster. It is a mod that allows the game to be modded with NVIDIA's RTX Remix.
It comes with a few enhanced assets and GTAIV-AutoPBR.

There are obvious drawbacks, and things that will not work with such a new title, don't expect this to be perfect.
RTX Remix has a certain overhead because of how it works and intercepts the game's draw calls.

You'll experience CPU bottlenecks because of the amount of detailed meshes the game is rendering,
which means that the performance you'll see in certain places is not entirely due to pathtracing.

The mod comes with a custom Remix Runtime required for a few game specific features
and with Ultimate ASI Loader to load the Compatibility Mod itself.

The good:

• Most objects rendered via fixed function to increase performance
• Cascaded anti culling of static objects (wip)
• All game lights (including the sun) are translated to remix lights
• Ability to create overrides for translated game lights (change position, color, intensity etc.)
• Vehicles now feature two headlights and two rear lights instead of single, centered ones
• Dynamic emissive surfaces work (vehicle lights, building-windows, shops etc.)
• Dynamic wetness that works similar to the original game
  (only outdoors and with falloff on angled surfaces + raindroplets/impacts)
• Raindroplets on vehicles and character clothing
• Working vehicle dirt and livery
• Modification of remix runtime variables based on current timecycle settings
• Mobilephone works (but it is 3D and currently scales with the camera fov)
• Modified vertex shaders (based on FusionFix) so that remix is able to capture surface normals
• Ability to spawn unique marker meshes that can be hidden based on distance, weather or time of day (these can be used to attach remix replacements or scene lights)
• Screenshot Mode and FreeCam Mode
• FusionFix compatible (custom fork: GTAIV.EFLC.FusionFix.RTXRemix)
• Many many tweakable settings via the in-game F4 menu
• A few PBR materials, mesh and texture fixes
• Installer

The bad:

• CPU Bottlenecked (reduce draw distance / quality)
• Mobilephone UI looks a little broken
• Anti-Culling is not perfect yet
• TV's are not working
• No blood on peds

Installing

• Grab the latest Release and follow the instructions found there

Uninstalling

• Deleting the d3d9.dll and a_gta4-rtx.asi should be enough
• Re-install the official FusionFix mod if you used the custom Fork

Usage

• Run the game like normal
• Press F4 to open the in-game gui for some compatibility tweaks or debug settings
• If you notice heavy stuttering, launch the game with the included _LaunchWithProcessorAffinity_2Cores_GTA4.bat.
  Doing this will assign 2 cores to GTA4 and the rest to Remix. If you want a 50/50 split, use _LaunchWithProcessorAffinity_Half_GTA4__Half_Remix.bat

Tip

Troubleshooting / in-depth guides, usage information and remix runtime changes can be found in the [Wiki]

Compiling

• Clone the repository git clone --recurse-submodules https://github.com/xoxor4d/gta4-rtx.git
• Optional: Setup a global path variable named GTA4_ROOT that points to your game folder (where GTAIV.exe is located)
• Run generate-buildfiles_vs22.bat to generate VS project files
• Compile the mod
• If you did not setup the global path variable:
  rename gta4-rtx.dll to a_gta4-rtx.asi and copy it into your game directory (next to GTAIV.exe)
• If you have not installed a release build before, make sure to copy everything within the assets folder into the game directory
• Make sure to also install: gta4-rtx-base-mod

Credits

• NVIDIA - RTX Remix
• People of the showcase discord - especially the nvidia engineers ✌️
• Dear ImGui
• imgui-blur-effect
• minhook
• toml11
• miniz
• Ultimate-ASI-Loader
• AssaultKifle47
• FusionFix
• FusionShaders
• Rage-Shader-Editor
• IV-SDK
• IV-SDK-DotNet
• DayL
• Entity
• Gabdeg
• Hemry
• Danlopand / Thundery_Dan
• All 🍓 Testers

And of course, all my fellow Ko-Fi and Patreon supporters
and all the people that helped along the way!