function round(cx, cy, sx, sy, ex, ey, verts, clockwise) {
    var cx2p0x = sx - cx;
    var cy2p0y = sy - cy;
    var angle0 = Math.atan2(cx2p0x, cy2p0y);
    var angle1 = Math.atan2(ex - cx, ey - cy);
    if (clockwise && angle0 < angle1) {
        angle0 += Math.PI * 2;
    }
    else if (!clockwise && angle0 > angle1) {
        angle1 += Math.PI * 2;
    }
    var startAngle = angle0;
    var angleDiff = angle1 - angle0;
    var absAngleDiff = Math.abs(angleDiff);
    /* if (absAngleDiff >= PI_LBOUND && absAngleDiff <= PI_UBOUND)
    {
        const r1x = cx - nxtPx;
        const r1y = cy - nxtPy;

        if (r1x === 0)
        {
            if (r1y > 0)
            {
                angleDiff = -angleDiff;
            }
        }
        else if (r1x >= -GRAPHICS_CURVES.epsilon)
        {
            angleDiff = -angleDiff;
        }
    }*/
    var radius = Math.sqrt((cx2p0x * cx2p0x) + (cy2p0y * cy2p0y));
    var segCount = ((15 * absAngleDiff * Math.sqrt(radius) / Math.PI) >> 0) + 1;
    var angleInc = angleDiff / segCount;
    startAngle += angleInc;
    if (clockwise) {
        verts.push(cx, cy);
        verts.push(sx, sy);
        for (var i = 1, angle = startAngle; i < segCount; i++, angle += angleInc) {
            verts.push(cx, cy);
            verts.push(cx + ((Math.sin(angle) * radius)), cy + ((Math.cos(angle) * radius)));
        }
        verts.push(cx, cy);
        verts.push(ex, ey);
    }
    else {
        verts.push(sx, sy);
        verts.push(cx, cy);
        for (var i = 1, angle = startAngle; i < segCount; i++, angle += angleInc) {
            verts.push(cx + ((Math.sin(angle) * radius)), cy + ((Math.cos(angle) * radius)));
            verts.push(cx, cy);
        }
        verts.push(ex, ey);
        verts.push(cx, cy);
    }
    return segCount * 2;
}
Buffers vertices to draw an arc at the line joint or cap.

Ignored from docs since it is not directly exposed.
@ignore
@private
@param {number} cx - X-coord of center
@param {number} cy - Y-coord of center
@param {number} sx - X-coord of arc start
@param {number} sy - Y-coord of arc start
@param {number} ex - X-coord of arc end
@param {number} ey - Y-coord of arc end
@param {Array<number>} verts - buffer of vertices
@param {boolean} clockwise - orientation of vertices
@returns {number} - no. of vertices pushed