How to use BulletConfig.cmake and UseBullet.cmake in CMakeLists.txt

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Hello,

I am new in CMake. I have installed Bullet 2.83.7 using CMake-GUI. I use this version because it is small and Ammo.js uses this version. But I have tied Bullet 3.25 too and it is the same. So, Bullet 2.83.7 was installed to the directory: E:\libs\bullet3-2.83.7-prefix\win

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I see two files here: E:\libs\bullet3-2.83.7-prefix\win\lib\cmake\bullet

BulletConfig.cmake

#                                               -*- cmake -*-
#
#  BulletConfig.cmake(.in)
#

# Use the following variables to compile and link against Bullet:
#  BULLET_FOUND              - True if Bullet was found on your system
#  BULLET_USE_FILE           - The file making Bullet usable
#  BULLET_DEFINITIONS        - Definitions needed to build with Bullet
#  BULLET_INCLUDE_DIR        - Directory where Bullet-C-Api.h can be found
#  BULLET_INCLUDE_DIRS       - List of directories of Bullet and it's dependencies
#  BULLET_LIBRARIES          - List of libraries to link against Bullet library
#  BULLET_LIBRARY_DIRS       - List of directories containing Bullet' libraries
#  BULLET_ROOT_DIR           - The base directory of Bullet
#  BULLET_VERSION_STRING     - A human-readable string containing the version

set ( BULLET_FOUND 1 )
set ( BULLET_USE_FILE     "lib/cmake/bullet/UseBullet.cmake" )
set ( BULLET_DEFINITIONS  "" )
set ( BULLET_INCLUDE_DIR  "include/bullet" )
set ( BULLET_INCLUDE_DIRS "include/bullet" )
set ( BULLET_LIBRARIES    "LinearMath;BulletCollision;BulletDynamics;BulletSoftBody" )
set ( BULLET_LIBRARY_DIRS "lib" )
set ( BULLET_ROOT_DIR     "E:/libs/bullet3-2.83.7-prefix/win" )
set ( BULLET_VERSION_STRING "2.83" )

UseBullet.cmake

#                                               -*- cmake -*-
#
#  UseBullet.cmake
#


add_definitions     ( ${BULLET_DEFINITIONS} )
include_directories ( ${BULLET_INCLUDE_DIRS} )
link_directories    ( ${BULLET_LIBRARY_DIRS} )

My question is how to use these files in CMakeLists.txt? I have asked Google AI. This is the answer: https://g.co/gemini/share/c4b5e4cadd0a

Understanding BulletConfig.cmake and UseBullet.cmake

Before diving into their usage, let's briefly understand these files:

• BulletConfig.cmake: This file is typically generated during the build process of the Bullet Physics SDK. It contains configuration information about the installed Bullet library, including paths to libraries, include directories, and other relevant settings.
• UseBullet.cmake: This is a CMake script that simplifies the process of finding and linking against the Bullet library. It reads the configuration information from BulletConfig.cmake and sets up the necessary CMake variables and targets.

Integrating Bullet into Your CMake Project

1. Find the BulletConfig.cmake file:

• System-wide installation:
• • If Bullet is installed system-wide, CMake should be able to find it automatically.
• Custom installation:
• If Bullet is installed in a custom location, you'll need to provide the path to CMake. You can do this by setting the BULLET_ROOT environment variable or by using the find_package command with appropriate hints.

2. Include the UseBullet.cmake script in your CMakeLists.txt:

include(UseBullet)

3. Find and link the Bullet library:

find_package(Bullet REQUIRED)

# Link your target to the Bullet library
target_link_libraries(your_target PRIVATE Bullet::BulletDynamics Bullet::BulletCollision)

Replace your_target with the actual name of your target (e.g., your executable or library). The specific Bullet components you need to link to may vary depending on your project's requirements.

Example CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(MyBulletProject)

# Find and include Bullet
include(UseBullet)
find_package(Bullet REQUIRED)

# Add executable
add_executable(my_bullet_app main.cpp)

# Link to Bullet libraries
target_link_libraries(my_bullet_app PRIVATE Bullet::BulletDynamics Bullet::BulletCollision)

Additional Considerations:

• Bullet Version: Ensure that the version of Bullet you're using is compatible with your project's requirements and the CMake version you're using.
• Platform-Specific Configurations: If you're building on multiple platforms, you may need to adjust the CMake configuration accordingly.
• Custom Build Settings: If you need to customize the build settings for Bullet, you can use the set command to modify variables before calling find_package(Bullet).

By following these steps and considering the additional points, you should be able to effectively integrate the Bullet Physics SDK into your CMake-based project.

I try to use the guide above. This is my CMakeListst.txt:

cmake_minimum_required(VERSION 3.20)

project(cmake-bullet-physics-opengles20-sdl3-cpp)
add_executable(app)

target_sources(app
PRIVATE
    E:/libs/glad-2.0.6/src/glad.c
    src/main.cpp
)

include(UseBullet)
find_package(Bullet REQUIRED)
message(${BULLET_FOUND})
find_package(SDL3)
# Link your target to the Bullet library
target_link_libraries(app PRIVATE Bullet::BulletDynamics Bullet::BulletCollision Bullet::BulletSoftBody Bullet::LinearMath SDL3::SDL3)

target_compile_definitions(app PRIVATE SDL_MAIN_USE_CALLBACKS)

I use this command to config:

config-win.bat

set BULLET_ROOT=E:/libs/bullet3-2.83.7-prefix/win
cmake -G "MinGW Makefiles" -S . -B dist/win -DSDL3_DIR=E:/libs/sdl-3.1.3-prefix/win/lib/cmake/SDL3

Output:

E:\_Projects\OpenGL\SDL3\cmake-bullet-physics-opengles20-sdl3-cpp>cmake -G "MinGW Makefiles" -S . -B dist/win -DSDL3_DIR=E:/libs/sdl-3.1.3-prefix/win/lib/cmake/SDL3
CMake Error at CMakeLists.txt:58 (include):
  include could not find requested file:

    UseBullet


-- Found Bullet: E:/libs/bullet3-2.83.7-prefix/win/lib/libBulletDynamics.a
TRUE
-- Configuring incomplete, errors occurred!

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This works:

target_include_directories(app PRIVATE ${BULLET_INCLUDE_DIR})
find_package(Bullet REQUIRED)
find_package(SDL3)
target_link_libraries(app PRIVATE ${BULLET_DYNAMICS_LIBRARY} ${BULLET_COLLISION_LIBRARY} ${BULLET_MATH_LIBRARY} SDL3::SDL3)

config-win.bat

set BULLET_ROOT=E:/libs/bullet3-2.83.7-prefix/win
cmake -G "MinGW Makefiles" -S . -B dist/win -DSDL3_DIR=E:/libs/sdl-3.1.3-prefix/win/lib/cmake/SDL3

build-win.bat

cd dist\win
cmake --build .