Daniel's Notes

Setting up your SwiftGodot GDExtension

3 min read

See Also

Docs

Steps

  1. [[#define-you-gdextension-file|Define you .gdextension file]]
  2. Build Your GDExtension in Terminal
  3. Copy the build targets into your Godot project

See also: Using a Build Script.

Define you .gdextension file

Define your .gdextension file in TOML syntax.

Example .gdextension file for SwiftGodot

[configuration]
entry_symbol = "swift_entry_point"
compatibility_minimum = 4.2
reloadable = true # specifies that the editor should reload the extension when the editor window loses and regains focus. See Godot issue #80284 for more details.
    # Note: If Godot is crashing, you may want to try turning off or removing this `reloadable` setting.
 
 
[libraries]
macos.debug = "res://bin/libSimpleRunnerDriver.dylib"
 
 
[dependencies]
macos.debug = {"res://bin/libSwiftGodot.dylib" : ""} # Used to copy the library into the application when exporting the project
# The name of the file corresponds to the built version of the dynamic library

Build Your GDExtension in Terminal

See docs tutorial Section 3 step 4.

Run:

swift build --configuration debug

Copy the build targets into your Godot project

See docs tutorial Section 3 step 5 and 6.

How do we automate this?

There must be a way to automate this so that it is quicker, easier and less error prone. Perhaps we should use a makefile or a script? See Using a Build Script.

Using a Build Script

Here is an example build script1 which can be used to copy the build targets into your Godot project. And here is an explanation of how the script works.

#!/bin/sh
SWIFTBUILD="/usr/bin/xcrun swift build -c $1"
GODOT_BIN_PATH="./godot/bin/"
BUILD_OUTPUTDIR=""
 
DoBuild () {
	local SPECIFIC_SWIFTBUILD="$SWIFTBUILD $1"
	local SWIFTBUILD_GETOUTPUT="$SPECIFIC_SWIFTBUILD --show-bin-path"
	BUILD_OUTPUTDIR=$($SWIFTBUILD_GETOUTPUT)
	 
	if $SWIFTBUILD; then
		# Remove the generated files because their presence bothers VSCode
		rm EntryPoint.generated.*
		echo "Build successful"
	else
		exit
	fi
}
 
CopyResult () {
	local OUTPUTDIR=$1
	mkdir -p "$GODOT_OUTPUT_PATH"
	echo "Copy output to $GODOT_OUTPUT_PATH"
	rsync --checksum "$OUTPUTDIR"/libSanctuaryDriver.dylib "$GODOT_OUTPUT_PATH"
	rsync --checksum "$OUTPUTDIR"/libSwiftGodot.dylib "$GODOT_OUTPUT_PATH"
}
 
StandardOutputPath () {
	local OUTPUTDIR=$1
	if [[ "$OUTPUTDIR" =~ ([^/]+/+[^/]+)/*$ ]]; then
		LAST_TWO_DIRECTORIES=$BASH_REMATCH
		GODOT_OUTPUT_PATH="$GODOT_BIN_PATH$LAST_TWO_DIRECTORIES"
	fi
}
 
 
case $2 in
	mac)
		if [ $1 == "debug" ]; then
			DoBuild "--triple arm64-apple-macosx"
			StandardOutputPath $BUILD_OUTPUTDIR
			CopyResult $BUILD_OUTPUTDIR
		fi
		if [ $1 == "release" ]; then
			UNIVERSAL_OUTPUTDIR="./.build/apple/Products/Release"
			DoBuild "--triple arm64-apple-macosx"
			ARM_OUTPUTDIR=$BUILD_OUTPUTDIR
			DoBuild "--triple x86_64-apple-macosx"
			INTEL_OUTPUTDIR=$BUILD_OUTPUTDIR
			mkdir -p "$UNIVERSAL_OUTPUTDIR"
			echo "Creating Universal binaries…"
			lipo -create -output "$UNIVERSAL_OUTPUTDIR"/libSanctuaryDriver.dylib "$ARM_OUTPUTDIR"/libSanctuaryDriver.dylib "$INTEL_OUTPUTDIR"/libSanctuaryDriver.dylib
			lipo -create -output "$UNIVERSAL_OUTPUTDIR"/libSwiftGodot.dylib "$ARM_OUTPUTDIR"/libSanctuaryDriver.dylib "$INTEL_OUTPUTDIR"/libSwiftGodot.dylib
			GODOT_OUTPUT_PATH="$GODOT_BIN_PATH/universal-apple-macosx/release"
			CopyResult $UNIVERSAL_OUTPUTDIR
		fi
	;;
	*)
		echo "Second argument much be platform - currently only 'mac' is supported."
	;;
esac

And this is the .gdextension file that the script was designed to work with.

[configuration]
entry_symbol = "swift_entry_point"
compatibility_minimum = 4.2
reloadable = false
[libraries]
macos.debug = "res://bin/arm64-apple-macosx/debug/libSanctuaryDriver.dylib"
macos.release = "res://bin/universal-apple-macosx/release/libSanctuaryDriver.dylib"
[dependencies]
macos.debug = {"res://bin/arm64-apple-macosx/debug/libSwiftGodot.dylib" : ""}
macos.release = {"res://bin/universal-apple-macosx/release/libSwiftGodot.dylib" : ""}

Further Exploration

How does our GDExtension set up affect hot reloading?

It would be nice to be able to use Hot Reloading in SwiftGodot. I need to do more research to find out if this is currently viable and what the limitations are.

Footnotes

  1. Thanks to Chris Backas for sharing his script. ↩

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