Sharpen egdes using the SubSurf Modifier - floodlight I'm currently modelling a floodlight, but I'm stuck. The following image shows the front covering. In the middle, you see that the Subsurf modifier is smothing the three edges, but I want them to be sharp, so that the faces around it shape a frame.



What modifiers I've used:


What I've already tried:


I've selected the edges and marked them sharp (Ctrl + E --> Mark Sharp) and used this with the EdgeSplit modifier
I've tried the Auto Smooth option (Object Data --> Normals --> Auto Smooth)
I've tried using loop cuts but they don't work properly in my case
I've tried using Edge Crease (Shift + E)
I've tried changing the order of the modifiers


All these options didn't work for me, so I'm thankfull for all help ;)
It appears you already tried a Crease factor on those edges using shift-e

https://docs.blender.org/manual/en/dev/modeling/meshes/editing/edges.html


  This edge property, a value between (0.0 to 1.0), is used by the
  Subdivision Surface Modifier to control the sharpness of the edges in
  the subdivided mesh. This operator enters an interactive mode (a bit
  like transform tools), where by moving the mouse (or typing a value
  with the keyboard) you can set the (average) crease value of selected
  edges. A negative value will subtract from the actual crease value, if
  present. To clear the crease edge property, enter a value of -1.


It turns out creasing just the edges of the opening is not enough.  You also have to crease the diagonal edges that have a vertex on the opening: