Cleaning up shader code

[4LT]

Hello @andrei-drexler, I tried reaching out to you via Discord, but I see you haven't been on since, and this is probably a better venue for the discussion. Basically I wanted to play around with the shader code in my own branch for funzies, but found the existing shader code unpleasant to work with. I just don't like the way the code is split into string literals glued together with macros, mixing of GLSL pre-processor directives with C pre-processor directives, etc.

Basically my planned method would be to split up the shaders into their own .vert/.frag/.compute files with shared code in their own .glsl files that could be included by the shaders at build time. (Still working on a viable include mechanism, thinking of exploiting gcc -E currently.) Then I'd take the pre-processed shaders and generate source files via xxd -i which could then be built and linked.

I wanted to know if you'd accept such changes in a PR, and if so if there's any requirements you have WRT build and runtime. So far as I can tell I can implement this with 0 impact on the runtime, and no additional build dependencies*.

Most significant cons I can see is more complicated build, including having to distinguish between human-written C files and generated C files, but the pros are easier-to-maintain shaders.

*MingW seems to cover all scripting needs via bash and Tcl

[4LT]

Actually, would loading the shader files at runtime be preferable? I was thinking 0 runtime impact would be best, but there's a point at which having more comprehensible builds could outweigh that need.

[EDIT]

I've come up with a solution to pre-process the shaders and convert them to C files in one go, so there's no need for intermediate files and everything can be concatenated into a single C file!

#!/bin/sh

OUT=shaders.c
HEADER=shaders.h
ppflags="-E -P -x c"
cpp=cc

echo "#include \"$HEADER\"" >"$OUT"

while [ "$1" != "" ] ; do
    if [ "$1" == "-f" ] ; then
        shift
        ppflags="$ppflags $1"
    elif [ "$1" == "-c" ] ; then
        shift
        cc="$1"
    else
        shaderpath=$1
        shaderfile=`basename "$shaderpath"`
        shadername=`echo "glsl_$shaderfile" | sed 's/[ -.]/_/g'`

        ( $cpp $ppflags $shaderpath && head -c 1 /dev/zero )\
            | xxd -i /dev/stdin\
            | sed s/_dev_stdin/$shadername/\
            >>"$OUT"
    fi

    shift
done

Made to plug into the Makefiles with something like $(SHADERDIR)/genc.sh -c $(CC) -f "-DMY_COOL_FLAG=1" $(SHADERDIR)/*.vert $(SHADERDIR)/*.frag $(SHADERDIR)/*.compute

[4LT]

Ack! Might be more involved than I had hoped, since shaders are constructed dynamically. So there is a reason there's both C preprocessor and GLSL preprocessor. Need some way of escaping the GLSL directives

[EDIT]

Okay, I did find a solution, replace the # in the GLSL directives with @ and substitute them back in genc.sh

[4LT]

I've got it working now 😄 just need to fix up the Makefiles