Update CLion docs + add linux (#64)

* update tutorial for clion

* add linux clion docs

Author: Prevter

assets/clion_addconfiguration.png

@@ -128,43 +128,74 @@ If there are errors similar to VS Code (such as `#include <Geode/modify/MenuLaye
 
 # CLion
 
-No additional plugins are needed - the only thing you need to do is to set the CMake options correctly. When you open your mod's directory in CLion for the first time, you'll be met with an Open Project Wizard:
+* [CLion on Windows](#clion-on-windows)
+* [CLion on Linux](#clion-on-linux)
+
+## CLion on Windows
+
+No additional plugins are needed - the only thing you need to do is to configure your toolchain correctly. When you open your mod's directory in CLion for the first time, you'll be met with an Open Project Wizard:
 
 ![Image showing the CLion Open Project Wizard](/assets/clion_openprojectwizard.png)
 
-Here you need to make sure that:
+If this is the first time you're launching CLion, click the "Manage toolchains..." button, which will open a window where you can add a new toolchain.
+
+Here's an example of how to set up Visual Studio toolchain:
+
+![Image showing configured Visual Studio toolchain in CLion](/assets/clion_toolchainmsvc.png)
+
+And here's an example of how to set up Clang toolchain:
 
-1. Build type is set to `Release` or `RelWithDebInfo`; it cannot be Debug
-2. Toolchain is set to *Visual Studio*
-3. Generator is set to *Visual Studio 17 2022* or newer
-4. Build directory is set to *build*
+![Image showing configured Clang toolchain in CLion](/assets/clion_toolchainllvm.png)
+
+After that, in the Open Project Wizard, you need to make sure that:
+
+1. Build type is set to `Release` or `RelWithDebInfo` (we recommend `RelWithDebInfo`, since `Debug` might cause obscure crashes)
+2. Toolchain is set to *Visual Studio* or *Clang/LLVM*
+3. Generator is set to *Visual Studio 17 2022* or *Ninja* (if you have it installed)
 
 In the end it should look like this:  
 
 ![Image showing the CLion Open Project Wizard set up for Geode](/assets/clion_openprojectwizardsetup.png)
 
-Now you can press OK and CMake will run for the first time. The setup **will fail** until you build the project for the first time. In order to do that, go to the top right corner of the window where you'll see a dropdown saying `Add Configuration`.
+Now you can press OK and CMake will run for the first time. Wait until it finishes, and you should see a dropdown in the top right corner of the window that says `NameOfTheMod` (or whatever you called your project).
+Click on it, and pick `NameOfTheMod_PACKAGE` instead, which will trigger post build steps and package/install the mod to Geometry Dash.
+
+![Image showing the CLion Configuration dropdown](/assets/clion_addconfiguration.png)
+
+Now click the hammer icon in the top right corner next to build the mod:
+
+![Image showing the build button in CLion](/assets/clion_buildmod.png)
+
+The build should end with a message saying `Build finished` and (assuming you ran `geode config setup` before) the mod should now be installed to Geometry Dash.
 
-![Image showing the CLion Add Configuration dropdown](/assets/clion_addconfiguration.png)
+Don't forget to reload CMake after you add new files to the project.
+
+![Image showing how to rerun CMake in CLion](/assets/clion_reloadcmake.png)
 
-Click it and choose `Edit Configurations` and you'll be met with the Run/Debug Configurations window. Inside of it, click the plus button in the top left corner of the window and choose `CMake Application` from the popup:
+## CLion on Linux
 
-![Image showing the CLion Run/Debug Configurations window](/assets/clion_rundebugwindow.png)
+Pretty much the same as on [Windows](#clion-on-windows) except for setting up the toolchain.
 
-In the created configuration, click the `Target` dropdown and choose `All Targets`. You can also change the name to something else than "Unnamed".  
+First step is to create an environment file with the following content:
 
-![Image showing the CLion Run/Debug Configurations window with a configuration set up to compile the mod](/assets/clion_rundebugsetup.png)
+```bash
+export GEODE_SDK=$HOME/Documents/Geode
+export SPLAT_DIR=$HOME/.local/share/Geode/cross-tools/splat
+export CMAKE_TOOLCHAIN_FILE=$HOME/.local/share/Geode/cross-tools/clang-msvc-sdk/clang-msvc.cmake
+export HOST_ARCH=x86_64
+```
 
-Once that's done, you can click Apply and then OK. If it hasn't already, wait for CMake to finish its run. It might look something like this, with a line at the end saying `[Failed to reload]`.
+If the toolchain and/or splat weren't installed via `geode sdk install-linux`, modify the paths accordingly.
 
-![Image showing the failed CMake run output](/assets/clion_cmakerunfailed.png)
+Save it as `geode-env.sh` in your home directory (or wherever you want, just remember the path).
 
-Now click the hammer icon in the top right corner next to build the mod for the first time - **make sure that the dropdowns next to it say `RelWithDebInfo` and `Build Mod`** (or however you called your build task in the step before):
+> :warning: If you're using a non default shell (like fish), you might need to edit the environment file to use the correct syntax. For example, fish uses `set -gx VAR value` instead of `export VAR=value`.
 
-![Image showing the build button in CLion](/assets/clion_buildmod.png)
+Now, in the toolchain settings on the right side of the **Name** field, click the *Add environment* button and select the file you just created.
 
-The build should end with a message saying `Build finished` and (assuming you ran `geode config setup` before) the mod should now be installed to Geometry Dash. In order to make all the IDE features work correctly, reload CMake now, this run should end successfully with a message saying `[Finished]` at the end: 
+![Image showing how to configure crosscompiler toolchain in CLion](/assets/clion_toolchainlinux.png)
 
-![Image showing how to rerun CMake in CLion](/assets/clion_reloadcmake.png)
+After that, you can follow the same steps as on Windows to build your mod.
 
-Don't forget to reload CMake after you add new files to the project.
+For some specific mods/libraries (most people won't need this), you might also want to add the clang-cl toolchain. Everything is the same as with clang, except you have to use the `clang-cl-msvc.cmake` toolchain file instead. (Copy the environment file and change the `CMAKE_TOOLCHAIN_FILE` variable to point to the `clang-cl-msvc.cmake` file.)  
+Also make sure you're using `clang-cl` as the compiler in the toolchain settings.