ggraft

GLSL Graft is a cli tool allowing declarative injection patches for vanilla Minecraft shaders.

Overriding a core shader means copying Mojang's file and changing one line. Do that across twenty shaders and every Minecraft update becomes twenty manual re-copies, with no record of what you actually changed. ggraft keeps the edit under version control instead of the result: you declare which line to change, and it re-derives the overrides from any version on demand.

Terminology

Install

From PyPI

pip install ggraft

From source

Needs Python 3.11+ and Click.

pip install -e .

Quick start

ggraft init 26.3      # write ggraft.toml
ggraft pull           # fetch bases from misode/mcmeta
ggraft build          # apply patches -> patched shaders

Project configuration

ggraft.toml, found by walking up from the working directory. Paths resolve relative to it.

[base]
version = "26.3"                      # Minecraft version to pull
dir     = ".ggraft/base"              # where bases land (gitignore this)
source  = "assets/minecraft/shaders"  # subtree to pull, stripped from local paths
repo    = "misode/mcmeta"             # optional

[patches]
dir = "patches"

[output]
dir    = "assets/minecraft/shaders"   # required
header = true                         # stamp a provenance comment

Targets are relative to base.source: core/terrain.vsh reads from .ggraft/base/core/terrain.vsh and writes to <output.dir>/core/terrain.vsh.

Patches

name    = "iso-world"
targets = ["core/terrain.vsh", "core/rendertype_*.vsh"]
exclude = ["core/rendertype_lines.vsh"]

[[injection]]
op      = "declare"
include = "foo:iso.glsl"

[[injection]]
op    = "replace"
match = "gl_Position = ProjMat * ModelViewMat * vec4({expr}, 1.0);"
with  = "gl_Position = iso_position(ProjMat, ModelViewMat, vec4({expr}, 1.0));"

Injections apply in order, to every matching target. Patches stack in filename order.

Anchors

occurrence and every cannot both be set. multiline is only about letting a single {name} (or a regex .) cross one. A capture is non-greedy and must match at least one character, so vec4({expr}) does not match vec4().

Under regex = true the pattern is used as written, with ^ and $ matching at every line boundary, and its named groups (?P<name>...) fill the same {name} placeholders. In the replacement, a {name} that captured nothing is left exactly as it is, so GLSL braces and unrelated placeholders survive untouched.

No match is an unresolved injection, and so is an occurrence past the number of matches. More than one match without occurrence or every is an ambiguous injection, reported with the line of every match. Both name the patch, the injection index and the target, and both fail the build.

Operations

replace, insert and wrap are the anchored operations, so they also take regex, multiline, occurrence and every from Anchors. declare and function find their own place in the file and take no anchor.

declare inserts after the last #include at conditional-nesting depth zero, falling back to #extension then #version, and is idempotent. Appending after the last #include in the file would strand it inside an #ifdef branch that some shader variants skip.

Function injections

function targets a function body rather than a piece of text, the way a regular mixin does. at names a structural point, not an anchor pattern.

[[injection]]
op       = "function"
function = "main"
at       = "HEAD"           # HEAD by default
text     = "iso_setup();"

Text lands on a line of its own, indented like its neighbours. Multi-line text is indented line by line and keeps its blank lines; a one-line body stays on one line. Nothing is substituted, so {x} stays {x}.

INVOKE needs call, the function being called, and takes where (before by default, or after):

[[injection]]
op       = "function"
function = "main"
at       = "INVOKE"
call     = "fog_distance"
where    = "after"
text     = "iso_note_fog();"

It wraps the whole statement holding the call, never the expression inside it, and hits every call in the body. for one call in particular, use insert with a match anchor. A call that opens a block, like if (helper(x)) {, has no statement to follow: where = "after" is unresolved there, before always works.

Prototypes, calls and commented-out code are not definitions. An overloaded name is an ambiguous injection until occurrence = N picks one, and RETURN on a function that never returns is an unresolved injection, use TAIL insteaad.

Commands

-h/--help works on the group and every command, -V/--version prints the version, and -c/--config points at a specific ggraft.toml instead of searching upwards. pull --token also reads GITHUB_TOKEN.

Build guarantees

• --check dry run without output writes.
• A target pattern matching no base file fails the build. What a patch orphaned by a Minecraft update looks like.
• A patch applying to nothing fails the build, so a mistake in targets or exclude cannot disable a patch silently.
• Stale output is pruned. Shaders ggraft wrote are recorded in .ggraft/manifest.json, and a target dropped from a patch has its override deleted on the next build. Only manifest entries are ever deleted; -t disables pruning, since a partial build cannot tell what is stale.

Bases

Uses misode/mcmeta. Tree walk might be rate limited. Set GITHUB_TOKEN or pass --token to bypass the limit.

Tests

python -m unittest discover -s tests   # everything
python -m unittest tests.test_cli      # one module

One module per layer: test_structure, test_glsl, test_anchor, test_operations, test_engine, test_sources, test_cli. Shared shaders, project files and a network-free mcmeta client live in tests/fixtures.py.

Planned Features

• python module API
• backport handling of #moj_import rather than #include