lol/build/msbuild/config-build.xml

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup Label="Configuration">

    <!-- ======================================== -->
    <!-- Global Lol Engine Configuration Settings -->
    <!-- ======================================== -->

    <!-- Use OpenGL instead of Direct3D? -->
    <UseOpenGL>true</UseOpenGL>

    <!-- Use Bullet for our physics solver? -->
    <UseBullet>true</UseBullet>

  </PropertyGroup>
</Project>