SceneEditor

SceneEditor is an embeddable 3D editing component. It can be placed inside a View or any other LDLib2 UI layout.

It provides:

• a top bar,
• a Scene,
• orthographic / perspective camera switch,
• right mouse camera movement,
• mouse wheel movement speed changes while moving,
• a transform gizmo bar,
• translate / rotate / scale modes.

Scene Objects

IScene owns scene objects by UUID.

ISceneObject is the base object contract. It provides:

• a Transform,
• scene attach/detach lifecycle,
• child traversal,
• tick and frame update hooks.

SceneObject is the default implementation.

ISceneInteractable adds mouse hit testing through Ray and VoxelShape, plus click/release/drag callbacks.

ISceneRendering adds rendering hooks and applies the object's transform before drawInternal(...).

TransformGizmo targets an ITransform and updates it in translate, rotate, or scale mode.

Minimal Use

var sceneEditor = new SceneEditor();
sceneEditor.layout(layout -> {
    layout.widthPercent(100);
    layout.flex(1);
});

sceneEditor.scene
        .createScene(player.level())
        .setTickWorld(true)
        .useCacheBuffer();

var object = new BlockModelObject();
object.transform().position(player.position().toVector3f().add(0, 1, 0));

sceneEditor.addSceneObject(object);
sceneEditor.setTransformGizmoTarget(object.transform());

TestSceneEditor is the best source reference for a complete minimal screen.

Transform Gizmo

The transform gizmo in translate, rotate, and scale mode, from left to right.

The gizmo is drawn over the scene and gets the first chance at every left click. A drag that starts on a handle is never passed to the objects behind it.

Mode	Handle	Effect	Since
Translate	Axis arrow	Moves along one axis.
Translate	Planar handle	Moves in the plane of two axes.
Translate	Centre box (FREE)	Moves freely in the plane of the screen.	2.2.39
Rotate	Axis ring	Rotates about one axis. Since 2.2.39, only the near half of each ring is drawn, over a faint ball outline.
Rotate	Outer ring (SCREEN)	Rotates in the plane of the screen, about the camera's view direction.	2.2.38
Rotate	Inside the ball (TRACKBALL)	Free rotation; the grabbed point follows the cursor.	2.2.38
Scale	Axis box	Scales one axis.
Scale	Planar handle	Scales the two axes it spans.	2.2.39
Scale	Centre box (UNIFORM)	Scales all three axes, keeping proportions.	2.2.39

The handles are listed in TransformGizmo.Handle. The gizmo keeps a constant size on screen in both perspective and orthographic cameras.

Since 2.2.42 Right-click while dragging a handle to cancel the drag. The target goes back to where the drag started, and the update callback runs. Outside a gizmo drag, the right mouse button still moves the camera.

Gizmo Targets

Since 2.2.38

The gizmo can drive anything that implements com.lowdragmc.lowdraglib2.math.ITransform, not only a scene object's Transform. Transform implements ITransform, and the Transform overloads remain.

sceneEditor.setTransformGizmoTarget(myTransform, () -> markDirty());

Use this when your objects are not scene objects, for example because their data must load on a dedicated server or they already have their own hierarchy. You no longer need to mirror them with a proxy Transform.

ITransform getters follow two different rules:

Getters	Returns	Rule
position(), rotation()	World space	A snapshot you own. Safe to keep as a drag anchor.
localPosition(), localRotation(), localScale()	Local space	A read-only view that may be the live field. Do not mutate or keep it; change it through the setter.

There is no world scale: a world-space scale through a rotated parent cannot be expressed as a parent-relative transform. The gizmo writes world position, world rotation, and local scale.

An implementation whose world matrix comes from somewhere else, such as an animated bone, may refuse world-space writes.

Binary-incompatible change in 2.2.38

TransformGizmo#getTargetTransform() now returns ITransform instead of Transform. Code compiled against an older LDLib2 that calls it must be recompiled; cast the result if you need a Transform.

Clicking Objects

Changed 2.2.39

A left click in the scene is dispatched in this order:

1. The gizmo, if active.
2. Every ISceneInteractable whose collision shape the mouse ray hits, nearest first.
3. Interactables with an empty collision shape, in visiting order.

Dispatch stops at the first onMouseClick(ray) that returns true. Interactables that have a shape but are not hit by the ray do not receive the click.

Before 2.2.39, every interactable received every click and the results were combined, so overlapping objects were all told they were clicked.