Remove unnecessary `find_package(OpenGL)`

[Jayman2000]

Pull Request Type

• [ ] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [x] Build and Dependency changes
• [ ] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [ ] Network changes
  • [ ] Other changes

Description

Before this change, CMakeLists.txt would run find_package(OpenGL), but it would never use any of the targets or variables that calling find_package(OpenGL) produces. As a result, the call to find_package(OpenGL) didn’t really do anything.

Related Issues

Checklist

• [x] I have tested my changes locally and verified that they work as intended.
• [ ] I have documented any new or modified functionality.
• [x] I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• [x] I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

Additional Comments

[winterheart]

Actually OpenGL functions get loaded with dlopen() in dyna_gl.h. On Linux OpenGL functions get loaded via SDL_GL_GetProcAddress. By checking OpenGL we ensuring that system has OpenGL and SDL2 can use functions from it.

[Lgt2x]

Actually OpenGL functions get loaded with dlopen() in dyna_gl.h. On Linux OpenGL functions get loaded via SDL_GL_GetProcAddress. By checking OpenGL we ensuring that system has OpenGL and SDL2 can use functions from it.

However this logic only applies on the machine building the game, not the one running it. Using find_package is only useful at compile time to link our executable against the targets found, which is not the case here. A computer compiling the game in theory should not need OpenGL at all.

[Jayman2000]

@winterheart

Actually OpenGL functions get loaded with dlopen() in dyna_gl.h.

If we were linking the library at compile time, then I would agree that it would be good to give an error at compile time. However, if we’re using dlopen() to open the library at runtime, then I think think that we should only give an error at runtime. We already give an error at runtime.

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@Lgt2x

A computer compiling the game in theory should not need OpenGL at all.

Interestingly enough, there actually is a situation where computer compiling the game would need OpenGL. renderer/dyna_gl.h says:

#if defined(WIN32)
#include <GL/gl.h>
#else
#include "SDL_opengl.h"
#endif

Windows is the only platform that has a direct dependency on OpenGL, but it’s also the only platform where we don’t run find_package(OpenGL). (The line of code that I deleted was in an if(UNIX)). It’s OK to not call find_package(OpenGL) on Windows because we already depend on the Windows API, and the Windows API has included GL/gl.h since Windows 2000.