drawLensFrame method
Draws the circular lens frame for VR headset simulation.
Implementation
void drawLensFrame(Canvas canvas, Size viewportSize) {
final center = Offset(viewportSize.width / 2, viewportSize.height / 2);
final radius = min(viewportSize.width, viewportSize.height) * 0.48;
canvas.drawCircle(
center,
radius,
Paint()
..color = const Color(0xCC000000)
..style = PaintingStyle.stroke
..strokeWidth = 3,
);
}