Function b2MakeOffsetRoundedBox 

pub unsafe extern "C" fn b2MakeOffsetRoundedBox(
    halfWidth: f32,
    halfHeight: f32,
    center: b2Vec2,
    rotation: b2Rot,
    radius: f32,
) -> b2Polygon

Make an offset rounded box, bypassing the need for a convex hull. @param halfWidth the half-width (x-axis) @param halfHeight the half-height (y-axis) @param center the local center of the box @param rotation the local rotation of the box @param radius the radius of the rounded extension