UeTransformControls

The UeTransformControls class allows objects to be transformed (moved, rotated, scaled) using a visual gizmo.
It provides an interactive way for users to manipulate 3D objects in the scene.

Constructor

new UeTransformControls(camera, data = {})

Data parameters

Key	Type	Default	Description
view	number	0	The GameMaker view index to use for projections
onDragStart	function	undefined	Callback fired when dragging begins
onDrag	function	undefined	Callback fired every frame while dragging
onDragEnd	function	undefined	Callback fired when dragging stops
snapEnabled	boolean	false	Whether grid snapping is enabled by default
snapSize	number	10	The default snapping increment

Properties

Property	Type	Description
camera	UeCamera	The camera used for interaction
object	UeObject3D	The currently attached object
mode	string	Current mode: "move", "rotate", "scale"
space	string	Transformation space: "world" or "local"
size	number	Size multiplier for the gizmo
enabled	boolean	Whether the gizmo is active and visible
view	number	The GameMaker view index being used
dragging	boolean	Whether the user is currently dragging the gizmo
hoveredAxis	enum	The axis currently under the mouse (UE_GIZMO_AXIS)
selectedAxis	enum	The axis currently being dragged (UE_GIZMO_AXIS)
lineWidth	number	Thickness of gizmo lines in pixels (default: 3)
hitThreshold	number	Pixel distance for mouse picking (default: 10)
axisLength	number	Length of the axes in world units (default: 1.5)
snapEnabled	boolean	Whether grid snapping is enabled
snapSize	number	Current grid snapping increment

Methods

attach(object)

Attaches the controls to a 3D object.

detach()

Detaches the controls from the current object.

setMode(mode)

Sets the interaction mode.

• mode: "move", "rotate", or "scale".

updateGizmo()

Updates the gizmo's internal state (matrices, position, scale). Useful for updating the gizmo's orientation without processing mouse interactions.

update()

The main update loop. Handles interaction logic (picking and dragging). Must be called in the Step event.

render()

Draws the gizmo. Must be called in the Draw GUI event.

Modes

Move

Allows translation along the X, Y, Z axes or the XY, XZ, YZ planes. In "local" space, axes align with the object's rotation.

Rotate

Allows rotation around the X, Y, Z axes. Provides a screen-space rotation circle (outer ring).

Scale

Allows scaling of the object.

• Axes (Red, Green, Blue): Scale along specific local axes.
• Planes: Scale along two axes simultaneously.
• Center Cube: Uniform scaling on all axes.
  • Uniform scaling uses a visual "drag" distance logic for intuitive control.

Snapping

UeTransformControls supports grid snapping for the Move mode (translation). When enabled, coordinates will be rounded to the nearest multiple of snapSize.

• snapEnabled: Toggle snapping on/off.
• snapSize: Set the increment for snapping (e.g., 10, 50, 100 world units).

In the editor, this can be toggled using the Grid Snap icon in the scene tools bar.

Callbacks

The controls use callbacks provided in the data struct during initialization.

• onDragStart: Fired when the user starts dragging a gizmo axis.
• onDrag: Fired every frame while the gizmo is being dragged.
• onDragEnd: Fired when the user releases the mouse button.

Usage Example

// Create controls
var transformControls = new UeTransformControls(camera, {
    view: 0,
    onDrag: function() {
        show_debug_message("Object is being transformed!");
    }
});

// Attach to an object
transformControls.attach(myObject);

// Set mode
transformControls.setMode("move");

// In Step Event
transformControls.update();

// In Draw GUI Event
transformControls.render();