`DirectionalLight` has no target

[vidartf]

Three's DirectionalLight should have a target in addition to position. I also notice that the position and castShadow attributes of DirectionalLight are not correctly synced to the browser (at least, according to the console log).

For the following Python code:

light = pythreejs.DirectionalLight(
    intensity=0.6,
    position=[20., -20., 10.],
    castShadow=True,
    color='red',
)

The following is logged in the browser console:

THREE.DirectionalLight:

castShadow: false,
children: Array[0]
color: THREE.Color
eulerOrder: (...)
frustumCulled: true
id: 96
intensity: 0.6
layers: THREE.Layers
matrix: THREE.Matrix4
matrixAutoUpdate: true
matrixWorld: THREE.Matrix4
matrixWorldNeedsUpdate: false
modelViewMatrix: THREE.Matrix4
name: ""
needsUpdate: true
normalMatrix: THREE.Matrix3
parent: THREE.Scene
position: THREE.Vector3
quaternion: THREE.Quaternion
receiveShadow: undefined
renderOrder: 0
rotation: THREE.Euler
rotationAutoUpdate: true
scale: THREE.Vector3
shadow: THREE.LightShadow
target: THREE.Object3D
threejs_view: child
type: "DirectionalLight"
up: THREE.Vector3
useQuaternion: (...)
userData: Object
uuid: "57BA8404-C7C1-46C7-A1AC-6D456318C9C1"
visible: true
__proto__: THREE.Light

It does however work for Meshes.

[vidartf]

Note: I added the light to the scene, and not the camera (which I see is common in the examples). This was done as I do not want the light to rotate together with the camera.

[jasongrout]

Can you see if #82 solves the castShadow not updating problem?

[jasongrout]

Please note that all 3d objects have a look_at method which can set the 'target': d=DirectionalLight(); d.look_at(d.position, target.position).

[vidartf]

@jasongrout Regarding the look_at function, as far as I can tell it sets the rotation of the object? If so, this won't work for DirectionalLight. From its docs:

A Note about Position, Target and rotation: A common point of confusion for directional lights is that setting the rotation has no effect. This is because three.js's DirectionalLight is the equivalent to what is often called a 'Target Direct Light' in other applications. This means that its direction is calculated as pointing from the light's position to the target's position (as opposed to a a 'Free Direct Light' that just has a rotation component). The reason for this is to allow the light to cast shadows - the shadow camera needs a position to calculate shadows from.

The target is of course not strictly needed - one could instead to an appropriate modification of the position - but the abstraction is nice to have (especially as you can set the target to another object).

[jasongrout]

Thanks for quoting the docs. It looks like we need to expose the target then. Perhaps the target should be another object3d, which the light will follow?

[vidartf]

The docs says that it will accept anything that has a valid position attribute, but specifying it as another object3d should work well enough.

[vidartf]

This works partially in master: You can set the target after light initialization, but if set in the constructor call as a keyword argument the target object disappears. The mechanisms dealing with such objects (InitializedThreeType) need an overhaul.