@@ -2,8 +2,44 @@

 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

@@ -21,7 +57,8 @@ usage:

 arguments:

   <file>

-    File containing code to run. Specify - to read from stdin instead.

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

+    stdin instead.

 options:

   -m, --main

@@ -33,16 +70,28 @@ options:

 ## Dependencies

-All dependencies are [POSIX][] and are highly likely to be installed by default

+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

@@ -12,7 +12,8 @@ set -euC

 #////

 ###// arguments:

 ####/   <file>

-#////     File containing code to run. Specify - to read from stdin instead.

+#////     File containing code to run. If <file> is omitted or -, to read from

+#////     stdin instead.

 #////

 ###// options:

 ####/   -m, --main

@@ -59,3 +60,190 @@ file="${1-}"; shift $(($#>0));

 ## Parse unrecognized arguments

 [ $# -eq 0 ] || parse "unrecognized argument: '$1'"

+

+## Create temporary directory

+dir_tmp="$(mktemp -d)"

+trap 'rm -rf "$dir_tmp"' EXIT

+

+## Variables

+file_in="$dir_tmp/$(basename "$0").cpp"

+file_out="$file_in-out"

+if [ "$main" ]

+then

+  main_begin="int main() {"

+  main_end="}"

+fi

+if [ "$file" = "-" ]

+then

+  file=""

+fi

+

+## Generate

+cat << EOF > "$file_in"

+#include <cassert>

+#include <iostream>

+

+#define GLM_FORCE_SWIZZLE 1

+#define GLM_ENABLE_EXPERIMENTAL 1

+#include <glm/glm.hpp>

+#include <glm/gtx/io.hpp>

+

+using namespace std;

+using namespace glm;

+

+// Constants

+const int gl_MaxVertexAttribs = 16;

+const int gl_MaxVertexOutputComponents = 64;

+const int gl_MaxVertexUniformComponents = 1024;

+const int gl_MaxVertexTextureImageUnits = 16;

+const int gl_MaxGeometryInputComponents = 64;

+const int gl_MaxGeometryOutputComponents = 128;

+const int gl_MaxGeometryUniformComponents = 1024;

+const int gl_MaxGeometryTextureImageUnits = 16;

+const int gl_MaxGeometryOutputVertices = 256;

+const int gl_MaxGeometryTotalOutputComponents = 1024;

+const int gl_MaxGeometryVaryingComponents = 64;

+const int gl_MaxFragmentInputComponents = 128;

+const int gl_MaxDrawBuffers = 8;

+const int gl_MaxFragmentUniformComponents = 1024;

+const int gl_MaxTextureImageUnits1 = 16;

+const int gl_MaxClipDistances = 8;

+const int gl_MaxCombinedTextureImageUnits = 48;

+// OpenGL 4.0

+int gl_MaxTessControlInputComponents = 128;

+int gl_MaxTessControlOutputComponents = 128;

+int gl_MaxTessControlUniformComponents = 1024;

+int gl_MaxTessControlTextureImageUnits = 16;

+int gl_MaxTessControlTotalOutputComponents = 4096;

+int gl_MaxTessEvaluationInputComponents = 128;

+int gl_MaxTessEvaluationOutputComponents = 128;

+int gl_MaxTessEvaluationUniformComponents = 1024;

+int gl_MaxTessEvaluationTextureImageUnits = 16;

+int gl_MaxTessPatchComponents = 120;

+int gl_MaxPatchVertices = 32;

+int gl_MaxTessGenLevel = 64;

+// OpenGL 4.1

+int gl_MaxViewports = 16;

+int gl_MaxVertexUniformVectors = 256;

+int gl_MaxFragmentUniformVectors = 256;

+int gl_MaxVaryingVectors = 15;

+// OpenGL 4.2

+int gl_MaxVertexImageUniforms = 0;

+int gl_MaxVertexAtomicCounters = 0;

+int gl_MaxVertexAtomicCounterBuffers = 0;

+int gl_MaxTessControlImageUniforms = 0;

+int gl_MaxTessControlAtomicCounters = 0;

+int gl_MaxTessControlAtomicCounterBuffers = 0;

+int gl_MaxTessEvaluationImageUniforms = 0;

+int gl_MaxTessEvaluationAtomicCounters = 0;

+int gl_MaxTessEvaluationAtomicCounterBuffers = 0;

+int gl_MaxGeometryImageUniforms = 0;

+int gl_MaxGeometryAtomicCounters = 0;

+int gl_MaxGeometryAtomicCounterBuffers = 0;

+int gl_MaxFragmentImageUniforms = 8;

+int gl_MaxFragmentAtomicCounters = 8;

+int gl_MaxFragmentAtomicCounterBuffers = 1;

+int gl_MaxCombinedImageUniforms = 8;

+int gl_MaxCombinedAtomicCounters = 8;

+int gl_MaxCombinedAtomicCounterBuffers = 1;

+int gl_MaxImageUnits = 8;

+int gl_MaxCombinedImageUnitsAndFragmentOutputs = 8;

+int gl_MaxImageSamples = 0;

+int gl_MaxAtomicCounterBindings = 1;

+int gl_MaxAtomicCounterBufferSize = 32;

+int gl_MinProgramTexelOffset = -8;

+int gl_MaxProgramTexelOffset = 7;

+// OpenGL 4.3

+ivec3 gl_MaxComputeWorkGroupCount = {65535, 65535, 65535};

+ivec3 gl_MaxComputeWorkGroupSize = { 1024, 1024, 64 };

+int gl_MaxComputeUniformComponents = 512;

+int gl_MaxComputeTextureImageUnits = 16;

+int gl_MaxComputeImageUniforms = 8;

+int gl_MaxComputeAtomicCounters = 8;

+int gl_MaxComputeAtomicCounterBuffers = 1;

+// OpenGL 4.4

+int gl_MaxTransformFeedbackBuffers = 4;

+int gl_MaxTransformFeedbackInterleavedComponents = 64;

+

+// Vertex shader inputs

+int  gl_VertexID;

+int  gl_InstanceID;

+int  gl_DrawID;

+int  gl_BaseVertex;

+int  gl_BaseInstance;

+// Vertex shader outputs

+vec4  gl_Position;

+float gl_PointSize;

+float gl_ClipDistance[gl_MaxClipDistances];

+// Tessellation control shader inputs

+int gl_PatchVerticesIn;

+// Tessellation control shader outputs

+float gl_TessLevelOuter[4];

+float gl_TessLevelInner[2];

+// Tessellation evaluation shader inputs

+vec3 gl_TessCoord;

+// Geometry shader inputs

+int gl_PrimitiveIDIn;

+int gl_InvocationID;

+// Geometry shader outputs

+int gl_PrimitiveID;

+int gl_Layer;

+int gl_ViewportIndex;

+// Fragment shader inputs

+vec4 gl_FragCoord;

+bool gl_FrontFacing;

+vec2 gl_PointCoord;

+int gl_SampleID;

+vec2 gl_SamplePosition;

+int gl_SampleMaskIn[1];

+// Fragment shader outputs

+float gl_FragDepth;

+int gl_SampleMask;

+// Compute shader inputs

+uvec3 gl_NumWorkGroups;

+uvec3 gl_WorkGroupID;

+uvec3 gl_LocalInvocationID;

+uvec3 gl_GlobalInvocationID;

+uint  gl_LocalInvocationIndex;

+// Compute shader other variables

+uvec3 gl_WorkGroupSize;

+// Shader uniforms

+struct gl_DepthRange

+{

+    float near;

+    float far;

+    float diff;

+};

+int gl_NumSamples;

+

+// Functions

+void EmitVertex() {}

+void EndPrimitive() {}

+

+#define GLSLRUN 1

+

+${main_begin-}

+#line 1

+$(

+    sed ${file:+"$file"} \

+        -e 's/^\s*#version\>.*//' \

+        -e 's/^\s*#extension\>.*//' \

+        -e 's/^\s*layout\>.*//' \

+        -e 's/^\s*in\>\s\?//' \

+        -e 's/^\s*out\>\s\?//' \

+        -e 's/^\s*void\(\s\+main\>\)/int\1/' \

+)

+${main_end-}

+EOF

+

+## Optionally print

+if [ "$print" ]

+then

+  cat "$file_in"

+fi

+

+## Compile

+"${CXX-g++}" -Wall -I. -o "$file_out" "$file_in"

+

+## Run

+"$file_out"