4.2 KiB
Scripting
This page shows some examples in how to use the scripting API.
Editing the terrain
Using VoxelTool
TODO
LOD limitation
TODO
Editing performance
See Access to voxels and multithreading
Custom generator
You can provide your own voxel generator by extending VoxelGeneratorScript in either GDScript, C# or C++.
!!! note custom generators can also be created without scripts, using VoxelGeneratorGraph
Example
Here is how to make a bare bones generator usable with a blocky terrain. Make sure you use VoxelMesherBlocky as mesher.
Create a standalone script my_generator.gd with the following contents:
extends VoxelGeneratorScript
const channel : int = VoxelBuffer.CHANNEL_TYPE
func get_used_channels_mask() -> int:
return 1 << channel
func generate_block(buffer : VoxelBuffer, origin : Vector3, lod : int) -> void:
if lod != 0:
return
if origin.y < 0:
buffer.fill(1, channel)
if origin.x == origin.z and origin.y < 1:
buffer.fill(1, channel)
In your terrain scene, add another script to a node, which will setup your generator when the game starts. Code might differ a bit depending on how you structure your scene.
const MyGenerator = preload("my_generator.gd")
# Get the terrain
var terrain = $VoxelTerrain
func _ready():
terrain.stream = MyGenerator.new()
Though VoxelBuffer.fill() is probably not what you want to use, the above is a quick example. Generate_block generally gives you a block of 16x16x16 cubes to fill all at once, so you may also use VoxelBuffer.set_voxel() to specify each one individually. You can change the channel to VoxelBuffer.CHANNEL_SDF to get smooth voxels using another mesher such as VoxelMesherTransvoxel.
Thread-safety
Generators are invoked from multiple threads. Make sure your code is thread-safe.
If your generator uses resources or exports parameters that you want to change while it might be running, you should make sure they are read-only or copied per thread, so if the resource is modified from outside or another thread it won't disrupt the generator.
You can use Mutex to enforce single-thread access to variables, but use it with caution because otherwise you could end up limiting performance to one thread (while the other waits for the lock to be released). Using Read-Write locks and thread-locals are good options, unfortunately the Godot script API does not provide this.
Careful about lazy-initialization, it can cause crashes if two threads run it at the same time. Curve is one of the resources doing that: if you call interpolate_baked() and it wasn't baked yet, it will be baked at the very last moment. Here is an example of working around this:
extends VoxelGeneratorScript
const MountainsCurve : Curve = preload("moutains_curve.tres")
# This is called when the generator is created
func _init():
# Call `bake()` to be sure it doesn't happen later inside `generate_block()`.
MountainsCurve.bake()
# ...
A similar story occurs with Image. It needs to be locked before you can access pixels, but calling lock() and unlock() itself is not thread-safe. One approach to solve this is to lock() the image in _init() and leave it locked for the whole lifetime of the generator. This assumes of course that the image is never accessed from outside:
extends VoxelGeneratorScript
var image : Image
# This is called when the generator is created
func _init():
image = Image.new()
image.load("some_heightmap.png")
image.lock()
func generate_block(buffer : VoxelBuffer, origin : Vector3, lod : int) -> void:
# ... use image.get_pixel() freely ...
# ... but DO NOT use image.set_pixel() ...
func _notification(what: int):
if what == NOTIFICATION_PREDELETE:
# Called when the script is destroyed.
# I don't know if it's really required, but unlock for correctness.
image.unlock()
# ...
Image.lock() won't be required anymore in Godot 4.
Custom stream
TODO
Creating a terrain node
TODO