# [`glslrun`][]
 
 Run [GLSL][] code on the CPU.
 

 Generates a wrapper file including some [C++][] standard library functionality
 and [OpenGL Mathematics (GLM)][], compiles it with the systems C++ compiler (by
 default [`gcc`][], can be changed by setting the [environment variable][]
 `CXX`) and runs the result.
 
 This, of course, does not *really* run GLSL code on the CPU. For an actual GLSL
 compiler (but not to something that can run on the CPU), see [`glslang`][].
 
 The wapper does the following:
 
 -   C++ standard library
     -   Brings the `std` namespace into global scope.
     -   `#include`s [`cassert`][] for testing.
     -   `#include`s [`iostream`][] for printing.
 -   GLM
     -   Brings the `glm` namespace into global scope.
     -   `#define`s `GLM_FORCE_SWIZZLE` to enable [swizzling][] support.
     -   `#include`s [`glm/gtx/io.hpp`][] to enable [`iostream`][] support.
 -   Other
     -   `#define`s `GLSLRUN`.
     -   Defines [built-in variable][]s (like [`gl_Position`][]).
     -   Defines [built-in function][]s (like [`EmitVertex`][]).
 

 [`glslrun`]: https://git.rcrnstn.net/rcrnstn/glslrun
 [GLSL]: https://en.wikipedia.org/wiki/OpenGL_Shading_Language

 [C++]: https://en.wikipedia.org/wiki/C++
 [OpenGL Mathematics (GLM)]: https://glm.g-truc.net
 [`gcc`]: https://gcc.gnu.org
 [environment variable]: https://en.wikipedia.org/wiki/Environment_variable
 [`glslang`]: https://github.com/KhronosGroup/glslang
 [`cassert`]: https://en.cppreference.com/w/cpp/header/cassert
 [`iostream`]: https://en.cppreference.com/w/cpp/header/iostream
 [swizzling]: https://en.wikipedia.org/wiki/Swizzling_(computer_graphics)
 [`glm/gtx/io.hpp`]: http://glm.g-truc.net/0.9.9/api/a00332.html
 [built-in variable]: https://www.khronos.org/opengl/wiki/Built-in_Variable_(GLSL)
 [`gl_Position`]: https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl_Position.xhtml
 [built-in function]: https://www.khronos.org/opengl/wiki/Built-in_Function_(GLSL)
 [`EmitVertex`]: https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/EmitVertex.xhtml

 ## Usage
 
 `glslrun --help`:
 
 ```
 glslrun 1.0
 
 Run GLSL code snippets on the CPU.
 
 usage:
   glslrun [options] [--] [<file>]
   glslrun -h|--help
   glslrun --version
 
 arguments:
   <file>

     File containing code to run. If <file> is omitted or -, to read from
     stdin instead.

 
 options:
   -m, --main
     Generate an enclosing main() function.
 
   -p, --print
     Print the generated code that is passed to the compiler.
 ```
 

 ### Editor integrations
 
 #### Vim
 
 Add the following [Vimscript][] to `.vimrc`:
 
 ```vimscript
 autocmd FileType glsl
 \ set makeprg=glslrun
 ```
 
 [`:make`][] (or [`:Dispatch`][]) runs this configured `makeprg`.
 
 `:copen` opens the quickfix list.
 
 [Vimscript]: https://en.wikipedia.org/wiki/Vim_(text_editor)#Vim_script
 [`:make`]: https://vimhelp.org/quickfix.txt.html#:make
 [`:Dispatch`]: https://github.com/tpope/vim-dispatch
 
 #### Visual Studio Code
 
 Add the following [JSON][] task to `.vscode/tasks.json`:
 
 ```json
 {
     "version": "2.0.0",
     "tasks": [
         {
             "label": "glslrun",
             "type": "process",
             "command": "glslrun",
             "args": [ "${file}" ],
             "problemMatcher": "$gcc"
         }
     ]
 }
 ```
 
 <kbd>Ctrl</kbd><kbd>P</kbd> opens the Command Palette in which `task glslrun`
 can be typed.
 
 <kbd>Ctrl</kbd><kbd>Shift</kbd><kbd>\`</kbd> opens the terminal output.
 
 <kbd>Ctrl</kbd><kbd>Shift</kbd><kbd>M</kbd> opens the list of problems.
 
 [JSON]: https://en.wikipedia.org/wiki/JSON
 [launch configuration]: https://code.visualstudio.com/docs/editor/debugging#_launch-configurations
 

 ## Dependencies
 

 For compiling C++:
 
 -   C++ compiler (e.g. from [`g++`][])
 -   C++ standard library (e.g. from [`libstdc++`][])
 -   OpenGL Mathematics (GLM) (e.g. from [`libglm-dev`][])
 
 All other dependencies are [POSIX][] (except `mktemp`, but most Unix-like
 systems have some version), and are highly likely to be installed by default

 (e.g. they all have the [Debian priority][] `required`).
 
 -   `sh` (e.g. from [`bash`][] or [`dash`][])

 -   `rm`, `cat`, `mktemp` (e.g. from [`coreutils`][])

 -   `sed` (e.g. from [`sed`][])
 -   `awk` (e.g. from [`mawk`][])
 

 [`g++`]: https://packages.debian.org/g++
 [`libstdc++`]: https://packages.debian.org/libstdc++
 [`libglm-dev`]: https://packages.debian.org/libglm-dev

 [POSIX]: https://en.wikipedia.org/wiki/POSIX
 [Debian priority]: https://www.debian.org/doc/debian-policy/ch-archive.html#s-priorities
 [`bash`]: https://packages.debian.org/bash

 [`coreutils`]: https://packages.debian.org/coreutils

 [`dash`]: https://packages.debian.org/dash
 [`sed`]: https://packages.debian.org/sed
 [`mawk`]: https://packages.debian.org/mawk
 

 ## Example
 
 ```glsl
 TODO
 ```
 

 ## License
 
 Licensed under the [ISC License][] unless otherwise noted, see the
 [`LICENSE`](LICENSE) file.
 
 [ISC License]: https://choosealicense.com/licenses/isc/