66 lines
2.4 KiB
Markdown
66 lines
2.4 KiB
Markdown
|
# Attributes
|
||
|
|
|
||
|
|
An important concept in Geometry Nodes is attributes. Many trees transfer attributes between geometry, using a combination of *Capture Attribute* and *Transfer Attribute*.
|
||
|
|
|
||
|
|
Unfortunately, it takes quite a bit of code to use this common pattern.
|
||
|
|
|
||
|
|
```python
|
||
|
|
@tree("Skin")
|
||
|
|
def skin():
|
||
|
|
# Create a cube
|
||
|
|
c = cube()
|
||
|
|
# Capture the position
|
||
|
|
cube_position_attribute = c.capture_attribute(
|
||
|
|
data_type=CaptureAttribute.DataType.FLOAT_VECTOR,
|
||
|
|
value=position()
|
||
|
|
)
|
||
|
|
# Create a sphere
|
||
|
|
sphere = uv_sphere()
|
||
|
|
# Transfer the position to the sphere
|
||
|
|
transferred_position = cube_position_attribute.geometry.transfer_attribute(
|
||
|
|
data_type=TransferAttribute.DataType.FLOAT_VECTOR,
|
||
|
|
attribute=cube_position_attribute.attribute
|
||
|
|
)
|
||
|
|
# Make the sphere conform to the shape of the cube
|
||
|
|
return sphere.set_position(position=transferred_position)
|
||
|
|
```
|
||
|
|
|
||
|
|
Thankfully, a convenient `capture(...)` method is available on `Geometry`, which simplifies this function quite a bit.
|
||
|
|
|
||
|
|
```python
|
||
|
|
@tree("Skin")
|
||
|
|
def skin():
|
||
|
|
# Create a cube
|
||
|
|
c = cube()
|
||
|
|
# Capture the position
|
||
|
|
cube_position = c.capture(position())
|
||
|
|
# Create a sphere
|
||
|
|
sphere = uv_sphere()
|
||
|
|
# Make the sphere conform to the shape of the cube
|
||
|
|
return sphere.set_position(position=cube_position())
|
||
|
|
```
|
||
|
|
|
||
|
|
## How it Works
|
||
|
|
|
||
|
|
Internally, `capture(...)` works just like the more manual approach.
|
||
|
|
|
||
|
|
1. Capture the attribute from the source
|
||
|
|
|
||
|
|
In the example above, we capture the `position()` from the cube.
|
||
|
|
The data type is automatically inferred from the input. If you want to customize other options, simply pass them as keyword arguments to `capture(...)`.
|
||
|
|
|
||
|
|
```python
|
||
|
|
cube_position = c.capture(position())
|
||
|
|
cube_position = c.capture(position(), domain=CaptureAttribute.Domain.FACE) # Optionally pass other arguments available on `capture_attribute`.
|
||
|
|
```
|
||
|
|
|
||
|
|
2. Transfer the attribute to the target
|
||
|
|
|
||
|
|
`capture(...)` returns another function that calls `transfer_attribute` with the correct arguments passed automatically.
|
||
|
|
Call this returned function (which we store in the variable `cube_position`) to transfer the attribute.
|
||
|
|
In this example we also set the transferred cube position back onto the sphere.
|
||
|
|
|
||
|
|
```python
|
||
|
|
sphere.set_position(position=cube_position())
|
||
|
|
sphere.set_position(position=cube_position(mapping=TransferAttribute.Mapping.NEAREST)) # Optionally pass other arguments available on `transfer_attribute`.
|
||
|
|
```
|