[GRASS-dev] [GRASS GIS] #1736: wxNVIZ volume display crashes Mac

[GRASS GIS]

#1736: wxNVIZ volume display crashes Mac
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 Reporter:  cmbarton   |       Owner:  grass-dev@…              
     Type:  defect     |      Status:  new                      
 Priority:  critical   |   Milestone:  6.4.4                    
Component:  wxGUI      |     Version:  svn-releasebranch64      
 Keywords:             |    Platform:  MacOSX                   
      Cpu:  OSX/Intel  |  
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Changes (by annakrat):

  * milestone:  6.4.3 => 6.4.4


Comment:

 Update: crash happens when drawing isosurfaces both on Mac and Linux
 (tested on G7). It does not happen always, I think it depends on data.
 Testing data from Helena are
 [http://skagit.meas.ncsu.edu/~helena/grasswork/JR_7408MR_2m_t70.asci.zip
 here]. Try e.g. isosurface of value 10. This is the relevant part of Mac
 report:


 {{{
 0   libgrass_ogsf.7.0.svn.dylib         0x077aaf09 gvl_read_char + 41
 (gvl_calc.c:770)
 1   libgrass_ogsf.7.0.svn.dylib         0x077b0d59 gvld_isosurf + 3577
 (gvld.c:329)
 2   libgrass_ogsf.7.0.svn.dylib         0x077afea6 gvld_vol + 134
 (gvld.c:54)
 3   libgrass_ogsf.7.0.svn.dylib         0x0777a4ed GVL_draw_vol + 45
 (GVL2.c:410)
 4   libgrass_nviz.7.0.svn.dylib         0x0787c2af Nviz_draw_all_vol + 63
 (draw.c:186)
 5   libgrass_nviz.7.0.svn.dylib         0x0787c399 Nviz_draw_all + 153
 (draw.c:241)
 }}}


 The problem is (as debugger in Qt shows) that variable 'crnt_ev' in gvld.c
 on line 320 is 12:

 {{{
 pos[i] = edge_pos[crnt_ev];
 }}}

 but 'edge_pos' is a field with size 12 (see line 111) so it reads wrong
 data. The value of the variable 'crnt_ev' comes from a big look-up table
 (mc33_table.h, line 340). So either the size of the field 'edge_pos' is
 wrong or the table is wrong. On line 323 in gvld.c 'crnt_ev' is tested on
 value 12 so it seems that 12 is valid?

 The marching cubes algorithm is unfortunately too complicated and there
 are almost no comments in the code so I have no idea what all the numbers
 mean. I tried to set the size of the field 'edge_pos' to 13 and
 isosurfaces don't crash anymore (tested on Linux only) and look normally.
 But I have no idea if they are drawn correctly. Any ideas?

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/1736#comment:26>
GRASS GIS <http://grass.osgeo.org>