elmindreda / orcf

OFDR Resolution Cap Fix

OFDR Resolution Cap Fix

What?

This is a fix for the faulty video memory size check in the game Operation Flashpoint: Dragon Rising. When this fault causes the game to think there isn't enough video memory, it refuses to set any resolution larger than 1280x1024.

Put the ddraw.dll produced by this project in the same directory as OFDR.exe and the game should allow larger resolutions to be set.

This fix Works on My Machine™, but may not work for everyone.

Why?

I wanted to play Operation Flashpoint: Dragon Rising but couldn't see very far at the resolutions the game would allow.

How?

The game calls IDirectDraw7::GetAvailableVidMem early on to check if there is enough video memory for it to allow resolutions higher than 1280x1024. On my machine with a 2GB dedicated GPU and 16GB for the integrated GPU to borrow from, DirectDraw returns 128MB.

This project produces a shim ddraw.dll that returns one byte less than 2GB, the highest value the game appears to accept.

The DLL produced by this project is not a full replacement of the system DLL but does everything the game needs. It is placed in the same directory as OFDR.exe . It intercepts the IDirectDraw7 interface and the call to IDirectDraw7::GetAvailableVidMem and gives the game a value that satisfies it. Resolutions up to 1920x1080 have been successfully tested.

This fix is written in C11 and has been verified to build with Visual Studio, Clang-CL, Clang, MinGW-w64 and MinGW. You will need CMake to generate build files for your development environment.

MinGW has no DirectDraw headers so the MinGW-w64 ones are bundled in the deps directory. They are added to the project by CMake when needed.

Credits

• People discussing this bug in the Steam forum, whose observations of the bug got me started in the right direction
• archive.org, who had saved a copy of the DirectX 7 SDK documentation
• The previous fix, a replacement OFDR.exe with an unexplained 10MB added, which made me so suspicious I wrote this fix instead