# Application Issues

This page documents known issues with some OpenGL applications.

## Topogun

Topogun for Linux (version 2, at least) creates a GLX visual without requesting a depth buffer. This causes bad rendering if the OpenGL driver happens to choose a visual without a depth buffer.

Mesa 9.1.2 and later (will) support a DRI configuration option to work around this issue. Using the driconf tool, set the “Create all visuals with a depth buffer” option before running Topogun. Then, all GLX visuals will be created with a depth buffer.

## Old OpenGL games

Some old OpenGL games (approx. ten years or older) may crash during start-up because of an extension string buffer-overflow problem.

The problem is a modern OpenGL driver will return a very long string for the `glGetString(GL_EXTENSIONS)` query and if the application naively copies the string into a fixed-size buffer it can overflow the buffer and crash the application.

The work-around is to set the `MESA_EXTENSION_MAX_YEAR` environment variable to the approximate release year of the game. This will cause the `glGetString(GL_EXTENSIONS)` query to only report extensions older than the given year.

For example, if the game was released in 2001, do

    export MESA_EXTENSION_MAX_YEAR=2001

before running the game.

## Viewperf

See the Viewperf issues page for a detailed list of Viewperf issues.