[CrystalSpace] #970: Clipping problems for space warping portals

#970: Clipping problems for space warping portals
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 Reporter:  kickvb  |       Owner:  jorrit
     Type:  defect  |      Status:  new   
 Priority:  minor   |   Milestone:        
Component:  engine  |     Version:  V2.1  
 Keywords:          |  
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 A method such as ''iMeshWrapper::PlaceMesh()'' allows to avoid clipping
 issues while crossing a portal. It does so by putting the mesh in all the
 target sectors of the portals that are being crossed so that the mesh does
 not appear cut by the portal.

 This works correctly for portals with an identity warp transform, but it
 is problematic for space warping portals. In this last case, the mesh
 being put in both sectors should be put at two different places at the
 same time, although there is only one iMovable structure hence only one
 position possible.

 A more extreme case is when the portal warps within the same destination
 sector than the starting one. In this case the mesh should be in the same
 sector at two different places at the same time.

 Some ideas in order to fix that:
  * Have an additional 'offset transform' that can be defined per sector
 that contains a given iMovable.
  * Have only one sector per movable instead of a list, but have also an
 additional list of the portals that are currently being crossed.
  * When a space warping transform is crossed, then duplicate temporarily
 the whole iMovable scene tree.
  * Find some rendering solution able to avoid clipping problems when an
 object is crossing a portal.

-- 
Ticket URL: <http://www.crystalspace3d.org/trac/CS/ticket/970>
CrystalSpace <http://www.crystalspace3d.org/>
Free open-source 3D SDK.
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