Disable SDL2 by default

[aleck099]

USE_SDL is 1 by default
Everything is fine except for building SDL2
When USE_SDL=1, emcc will add an include path of its built-in SDL1, which contains same files with SDL2 (e.g. SDL_config.h)
Building SDL2 without additional flags will result in redefination errors

How to disable USE_SDL globally? Is there any configuration file or environment variable? Please don't tell me to use CFLAGS= because of many compability issues of many build systems

[sbc100]

If you don't want the system version of SDL you can use -sUSE_SDL=0

[sbc100]

Is there some reason the emscripten builtin SDL2 port doesn't work for you? (i.e. -sUSE_SDL=2)?

[sbc100]

If you really don't want to pass -sUSE_SDL=0 on the command line you could edit src/settings.js and change the default for USE_SDL from 1 to 0... we don't normally recommend editing this file, but its one option.

[aleck099]

If you really don't want to pass -sUSE_SDL=0 on the command line you could edit src/settings.js and change the default for USE_SDL from 1 to 0... we don't normally recommend editing this file, but its one option.

Finally I edited settings.js

[Akaricchi]

I think USE_SDL=1 is a bad default. SDL1 has been obsolete for years. How much maintained software even still depends on it?

[sbc100]

True perhaps the default should be changed 0. On the other hand doesn't this only effect folks who what to buiild an out-of-tree copy of SDL2. I wonder how common that is?

[Akaricchi]

Common enough to have been noticed by at least two people here. Building your own SDL isn't that crazy when you build for multiple platforms and want precise and centralized control over your dependencies. We do that in Taisei; I wrote meson build definitions for all of our deps and we use the same set of subprojects for official emscripten, windows, macos, and linux builds. Building a custom SDL also allows us to disable a bunch of dead code that our game is not using, such as the built-in 2D renderer.

[sbc100]

Re-opening because there is some ongoing discussion about whether its a good idea to make USE_SDL default to 0 instead of 1.

[Akaricchi]

FWIW, SDL3 is now under development, so even SDL2 will be on its way out fairly soon (hopefully more gracefully than SDL1 was).