2D controls

Sprites, shapes and text are controls in the same panel tree as 3D models, drawn in the Overlay phase of the same frame. There is no second framework to learn, and no UI event system — a button is a control with a delegate on it.

Where you position things

You lay out against DesignResolution, 1280×720 by default. BasicResolution is the box you actually write coordinates in, and what it equals depends on the platform.

The practical rule: anchor anything that must stay reachable to BasicResolution, and stretch backgrounds and edge decoration to ExtendResolution. That gives you a layout with no letterboxing on a 20:9 phone without maintaining a second design.

A resize recomputes Scale and ExtendResolution only. BasicResolution is deliberately left alone, so dragging a window edge does not reflow a mobile layout.

The five types

icon = new Sprite2D
{
    Name = "Assets/Setting.png",
    Color = Colors.White,
    PosX = 20, PosY = 20, Width = 48,
    OnClick = () => settingPanel.Alpha = 1f
};
AddControl(icon);

divider = new Shape
{
    ShapeType = ShapeType.Square,
    Color = Colors.DarkGray,
    PosX = 20, PosY = 80, Width = 240, Height = 1
};
AddControl(divider);

Sprites. SpriteBase carries what both sprite types need: a Color tint, Ext for the file extension, OriginWidth and OriginHeight for the source pixel size, and SourceX/Y/Width/Height for drawing one cell out of a sheet. Clock advances a sheet frame, FlipX and FlipY mirror it, and TextureOverride takes a one-shot upload — a path or already-decoded RGBA8 pixels — which the next update consumes and clears.

Shapes. ShapeType is Dot, Square, Circle, RoundRect, RectFrame, Gradual or GradualCircle, with Border for frame thickness. Curves are analytically antialiased rather than scaled bitmaps, so a circle is crisp at any size.

Billboards. Sprite3D.Mode chooses how it faces the camera: Spherical always faces you, Cylindrical turns only around world Y so a nameplate stays upright, and None hands orientation to the quaternion Rotation.

Interaction

Every control has OnClick and OnTouch, and both fire from inside the control's own Update. That has a consequence worth stating plainly: a control you forget to update never receives a click, even though it draws perfectly.

MouseOver is maintained for you and is part of the gate, along with Enable, Ready and Alpha > 0. There is no bubbling model, no focus system and no command pattern.

Draw order, and the two domains

Controls and panels implementing IRenderOrder sort by Layer, then Order, then insertion index — a stable total order, so a rebuilt list does not shuffle.

RenderDomain decides when in the frame a control is drawn, independently of where it sits in the tree.

Putting a diegetic screen inside the world in Scene is exactly right. Putting a HUD there is how you accidentally make your text ghost under TAA.

A 2D-only application

Set the domain on the app itself and the 3D passes cost you nothing:

RenderDomain = RenderDomain.Overlay;

That is what Samples/Creator does — same controls, same panel model, none of the scene cost. Domain resolution is inherited down the tree, so one line on the app covers every panel under it.

Panels you do not have to write