NX2navi/tools/build_shaders.py

"""Build the runtime's own shaders into C headers of SPIR-V words, and the files it embeds into headers of bytes.

The repository holds the shaders as source only. Each becomes runtime/<name>_spv.h, which declares
`static const uint32_t <name>_spv[]`; the headers are build outputs (ignored by git) and tools/build_game.py builds the
missing and the stale ones before it compiles the runtime. Three kinds of source:

    runtime/shaders/<name>.comp, .vert, .frag   GLSL, compiled with glslc (one name per shader) and checked with spirv-val
    runtime/shaders/<name>.mesh, .task          the same for the mesh fallback probe's mesh and task shaders (SPIR-V 1.5)
    runtime/shaders/<name>.spvasm               SPIR-V assembly, assembled with spirv-as and checked with spirv-val
    tools/make_dlaa_mask.py, make_mvobj_fs.py   shaders assembled in Python (ASSEMBLED); they need no other tool

One more kind of header is no shader: a file the runtime embeds (EMBEDDED: the menu's font) as a list of its bytes,
for a compiler without #embed (runtime/ui/menu.cpp includes it there). It needs no tool.

A compiled or assembled header records the SHA-256 of its source and is stale when that no longer matches; a Python
one is stale when its text is not what its script gives. glslc, spirv-as and spirv-val come from MSYS2 UCRT64 on
Windows (packages mingw-w64-ucrt-x86_64-shaderc and mingw-w64-ucrt-x86_64-spirv-tools) and from PATH elsewhere
(shaderc, spirv-tools). A folder that carries its headers ready-made (the build kit, tools/make_kit.py) needs none of
them: nothing there is stale.

    python tools/build_shaders.py [--check] [--all] [--runtime DIR]
"""

import argparse
import hashlib
import importlib.util
import os
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path

TOOLS = Path(__file__).resolve().parent
ROOT = TOOLS.parent
BIN = Path(r'C:\msys64\ucrt64\bin')   # Windows; elsewhere, and without MSYS2 there, the tools come from PATH
TARGET = 'vulkan1.1'
STAGES = {'.comp': 'compute', '.vert': 'vertex', '.frag': 'fragment', '.mesh': 'mesh', '.task': 'task'}
MESH_TARGET = 'vulkan1.2'   # mesh and task shaders need SPIR-V 1.4 or later
ASM = '.spvasm'
ASM_TARGET = 'vulkan1.3'
# header name -> the script beside this one that assembles it; the script's HEADER is the header's text
ASSEMBLED = {'dlaa_mask': 'make_dlaa_mask.py', 'mvobj_fs': 'make_mvobj_fs.py'}
# a file below runtime/ the runtime embeds -> the header of its bytes, below runtime/ too (git ignores it)
EMBEDDED = {'ui/fonts/Roboto-Medium.ttf': 'ui/roboto_ttf.h'}


def embedded(src):
    """True for a file of EMBEDDED: a binary file, read as it is."""
    return src.suffix not in STAGES and src.suffix not in (ASM, '.py')


def source_hash(src):
    data = src.read_bytes()
    return hashlib.sha256(data if embedded(src) else data.replace(b'\r\n', b'\n')).hexdigest()   # text: the same on a CRLF checkout


def bytes_header(src, runtime):
    """The header of an embedded file: its bytes as decimal numbers, to include inside an array's braces."""
    data = src.read_bytes()
    lines = [f'// Generated by tools/build_shaders.py from runtime/{src.relative_to(runtime).as_posix()}; do not edit.',
             f'// source sha256 {source_hash(src)}',
             f'// The file\'s {len(data)} bytes, for a compiler without #embed.']
    lines += [','.join(map(str, data[i:i + 32])) + ',' for i in range(0, len(data), 32)]
    return '\n'.join(lines) + '\n'


def header_of(src, words):
    name = src.stem
    how = (f'Generated from runtime/shaders/{src.name} (spirv-as --target-env {ASM_TARGET})' if src.suffix == ASM
           else f'Generated by tools/build_shaders.py from runtime/shaders/{src.name}')
    lines = [f'// {how}; do not edit.',
             f'// source sha256 {source_hash(src)}',
             '#pragma once',
             '#include <stdint.h>',
             f'static const uint32_t {name}_spv[] = {{']
    for i in range(0, len(words), 8):
        lines.append('    ' + ', '.join(f'0x{w:08x}' for w in words[i:i + 8]) + ',')
    lines.append('};')
    return '\n'.join(lines) + '\n'


def sources(runtime):
    """Every shader source with the header it becomes: the files of runtime/shaders and the scripts of ASSEMBLED that
    are there (a folder without them carries the headers ready-made)."""
    shaders = runtime / 'shaders'
    found = sorted(p for p in shaders.iterdir() if p.suffix in STAGES or p.suffix == ASM) if shaders.is_dir() else []
    out = [(p, runtime / f'{p.stem}_spv.h') for p in found]
    out += [(TOOLS / script, runtime / f'{name}_spv.h') for name, script in ASSEMBLED.items() if (TOOLS / script).is_file()]
    out += [(runtime / src, runtime / header) for src, header in EMBEDDED.items() if (runtime / src).is_file()]
    return out


def assembled_text(script):
    spec = importlib.util.spec_from_file_location(script.stem, script)
    mod = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(mod)
    return mod.HEADER


def read_text(header):
    return header.read_bytes().decode('utf-8').replace('\r\n', '\n') if header.is_file() else None


def stale(runtime):
    """The shader sources whose header is missing or no longer comes from them."""
    out = []
    for src, header in sources(runtime):
        text = read_text(header)
        if text is None:
            out.append(src)
        elif src.suffix == '.py':
            if text != assembled_text(src):
                out.append(src)
        elif f'// source sha256 {source_hash(src)}' not in text:
            out.append(src)
    return out


def tool(name):
    """The path of glslc, spirv-as or spirv-val; ends the run with the packages to install when it is not there."""
    exe = BIN / f'{name}.exe' if os.name == 'nt' else None
    if exe and exe.is_file():
        return str(exe)
    found = shutil.which(name)
    if found:
        return found
    where = (f'MSYS2 UCRT64 ({BIN}): pacman -S mingw-w64-ucrt-x86_64-shaderc mingw-w64-ucrt-x86_64-spirv-tools'
             if os.name == 'nt' else "PATH: install your distribution's shaderc and spirv-tools packages")
    sys.exit(f'build_shaders: {name} not found. The runtime\'s shaders are compiled when the game is built '
             f'(docs/building.md); {name} comes from {where}')


def words_of(src):
    with tempfile.TemporaryDirectory() as tmp:
        spv = Path(tmp) / 'out.spv'
        if src.suffix == ASM:
            target = ASM_TARGET
            subprocess.run([tool('spirv-as'), '--target-env', target, '-o', str(spv), str(src)], check=True)
        else:
            # "// build_shaders: keep functions" in a source: no optimisation, so its functions stay functions (the HDR
            # tonemap, which runtime/vk_hdr.c splices into the game's shader by function)
            target = MESH_TARGET if src.suffix in ('.mesh', '.task') else TARGET
            opt = [] if '// build_shaders: keep functions' in src.read_text(encoding='utf-8') else ['-O']
            subprocess.run([tool('glslc'), *opt, f'--target-env={target}', f'-fshader-stage={STAGES[src.suffix]}',
                            '-o', str(spv), str(src)], check=True)
        subprocess.run([tool('spirv-val'), '--target-env', target, str(spv)], check=True)
        data = spv.read_bytes()
    return [int.from_bytes(data[i:i + 4], 'little') for i in range(0, len(data), 4)]


def build(runtime, only=None):
    """Writes the headers of the sources in only (default: the stale ones) and returns how many it wrote."""
    todo = stale(runtime) if only is None else list(only)
    headers = dict(sources(runtime))
    for src in todo:
        text = (assembled_text(src) if src.suffix == '.py' else bytes_header(src, runtime) if embedded(src)
                else header_of(src, words_of(src)))
        header = headers[src]
        part = header.with_name(header.name + '.part')   # whole or not at all: another build may be reading the folder
        part.write_text(text, encoding='utf-8', newline='\n')
        part.replace(header)
        print(f'{header.name}: {src.stat().st_size} bytes of {src.name}' if embedded(src)
              else f'{header.name}: {text.count("0x")} words from {src.name}')
    return len(todo)


def main():
    ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    ap.add_argument('--check', action='store_true', help='only report headers that are missing or do not match their source')
    ap.add_argument('--all', action='store_true', help='build every header, not only the missing and the stale ones')
    ap.add_argument('--runtime', type=Path, default=ROOT / 'runtime')
    args = ap.parse_args()
    runtime = args.runtime.resolve()
    if args.check:
        bad = stale(runtime)
        headers = dict(sources(runtime))
        for s in bad:
            print(f'{headers[s]}: missing or stale, run tools/build_shaders.py')
        return 1 if bad else 0
    n = build(runtime, [s for s, _ in sources(runtime)] if args.all else None)
    if not n:
        print('build_shaders: every header matches its source')
    return 0


if __name__ == '__main__':
    sys.exit(main())