[GRASS-dev] [GRASS GIS] #2173: Tcl NVIZ: load state file "Error: must be surf_id set_mask_mode BOOLEAN"

[GRASS GIS]

#2173: Tcl NVIZ: load state file "Error: must be surf_id set_mask_mode BOOLEAN"
--------------------------------+-------------------------------------------
 Reporter:  hamish              |       Owner:  grass-dev@…              
     Type:  defect              |      Status:  new                      
 Priority:  major               |   Milestone:  6.4.4                    
Component:  Tcl/Tk NVIZ         |     Version:  svn-develbranch6         
 Keywords:  load state, raster  |    Platform:  Linux                    
      Cpu:  x86-64              |  
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 Hi,

 there is a bug in writing the saved-state file in tcl/tk NVIZ. It means
 that re-loading a state file with raster layers leads to an inconsistent
 internal state.

 The reason is the mask-map inversion status being written as "00" not "0".
 Fixing the file by hand solves the issue and lets you load the state file
 correctly.

 spearfish example:
 {{{
 GRASS> g.region -d
 GRASS> nviz elev=elevation.dem

    File --> Save State
    Save as "test.nviz"

 GRASS> head -n 27 test.nviz | tail -n 17
 surf*1390794941
 map elevation.dem
 0
 map elevation.dem
 0
 unset
 00
 unset
 const 60.000000
 unset
 #888888
 0.000000 0.000000 0.000000
 3 3
 2 2
 poly
 grid_surf
 gouraud


 GRASS> nviz state=test.nviz

 Loading raster map <elevation.dem at PERMANENT>...
  100%
 Loading raster map <elevation.dem at PERMANENT>...
  100%
 Translating colors from raster map <elevation.dem at PERMANENT>...
  100%
 Diagnostic: Error: must be surf_id set_mask_mode BOOLEAN --
   Load procedure for panel >>>start surf may not be defined
 }}}

 And the internal state becomes a bit messed up: The surface renders but
 the Raster Surfaces controls show none loaded.

 In map_obj.c set_mask_mode() fails because it is saved in the file as "00"
 not "0" (7th line of the 'surf' entry).

 The code that creates it is get_mask_mode() in
 visualization/nviz/src/map_obs.c, but that is using `sprintf(tmp, "%d",
 mode);` to create the string so I'm not seeing where/how the "00" is being
 introduced, since %d should lead to just "0".
 ?

 The work-around is to edit the .nviz state file by hand and change the
 "00" to "0". Then the "Load State" works as expected.

 Interestingly the first time I launch tcl nviz in 6.4.3 on a different
 machine it wrote out "0" but later attempts following the exact same
 series of clicks writes out "00".. smashed stack?

 see also scripts/panel_surf.tcl for the reading and writing of the
 session-state file (Nviz_surf_save() is well commented).


 Another question is if after fixing the source of the "00" trouble if we
 allow sloppy-read, i.e. to auto-translate 00 to 0 upon load so the user
 can load old+broken .nviz state files created by this bug. Or as a general
 policy if keeping work-arounds in the code base for old bugs generates too
 much code-clutter? In this case I would suggest to err on the side of
 being kind to the victims.


 thanks,
 Hamish

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/2173>
GRASS GIS <http://grass.osgeo.org>