read-pointer

name	read-pointer
description	Read mouse, touch, and pen input through BLIT386's unified pointer API with up to four slots. Use for clicking, dragging, painting, aiming, scrolling, or touch controls.

Read the mouse, touch, and pen

Mouse, touch, and pen share one "pointer" API with up to four slots. Slot 0 is the mouse or first touch.

When to use

Use for clicking, dragging, painting, aiming, scrolling, or touch controls.

How to do it

update() {
    if (BT.isPointerActive(0)) {
        const p = BT.pointerPos(0); // a Vector2i in screen pixels
        const move = BT.pointerDelta(0); // how far it moved this frame

        if (BT.isDown(BT.BTN_POINTER_A, 0)) this.paintAt(p); // primary button held
        if (BT.isPressed(BT.BTN_POINTER_A, 0)) this.startDrag(p);
        if (BT.isReleased(BT.BTN_POINTER_A, 0)) this.endDrag(p, move); // move as flick velocity
    }

    const wheel = BT.pointerScrollDelta; // a getter; wheel movement this frame
    this.zoom += wheel.y;
}

Key calls

• BT.pointerPos(slot?) / BT.pointerDelta(slot?) – methods, return Vector2i.
• BT.isPointerActive(slot?) – method; is a pointer present in that slot.
• BT.pointerScrollDelta – getter; wheel delta this frame.
• Buttons: BT.BTN_POINTER_A (primary), BTN_POINTER_B/C/D, BTN_POINTER_ANY, used with BT.isDown/isPressed/isReleased.
• BT.hideCursor() / BT.showCursor() – methods; hide or restore the OS cursor over the canvas.

Notes

• Slots: 0 = mouse or first touch; 1–3 = extra touches or pens (multi-touch).
• Read in update(). Positions are already in your screen's pixel coordinates.
• pointerDelta makes a good drag velocity – release while moving to "flick".

See docs/input.md.