| Re: IDLgrPolygon Leak? [message #69991] |
Wed, 03 March 2010 20:00  |
KRDean
Messages: 69
Registered: July 2006
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Member |
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On Mar 3, 5:10 pm, Karl <karl.w.schu...@gmail.com> wrote:
> On Mar 3, 1:24 pm, kBob <krd...@gmail.com> wrote:
>
>
>
>
>
>> Not a memory leak, but a polygon leak.
>
>> The 2010 IDL User Group meeting got me inspired to work with some
>> object graphics mapping.
>
>> However, I am running into some problems with adding a Shapefile to a
>> object graphics window. When I call the IDLgrPOLYGON to draw and fill
>> the shapefile vertices, there seems to be a leak or overflowing the
>> polygon.
>
>> Any thoughts on why. Sample code below. The IDLgrPOLYGON is set to
>> work with vertices that only have one part. Anything else, the
>> IDLgrPOLYLINE is used.
>
>> Kelly Dean
>> Fort Collins, CO
>
>> =============== Test_PolyShp ===============
>
>> ;+
>> ;
>> ; <P>Prepare Shapefile Entities for object model.
>> ;
>> ;----------------------------------------------------------- -----------
>> PRO CountryModel, oModelSHP
>
>> COMPILE_OPT DEFINT32, STRICTARR
>
>> shpFile = FILEPATH( Subdirectory=['resource', 'maps', 'shape'],
>> 'cntry02.shp' )
>> oSHP = OBJ_NEW( 'IDLffShape', shpFile )
>> IF ( OBJ_VALID( oSHP ) ) THEN BEGIN
>> oModelSHP = OBJ_NEW( 'IDLgrModel' )
>> oSHP -> GetProperty, N_ENTITIES = num_ent
>> FOR entn = 0, num_ent-1 DO BEGIN
>> ent = oSHP -> GetEntity( entn )
>> IF ( ent.n_parts GE 2 ) THEN BEGIN
>> cuts = [ (*ent.parts), ent.n_vertices ]
>> FOR partn = 0, ent.N_parts-1 DO BEGIN
>> ; oGon = OBJ_NEW('IDLgrPolygon', (*ent.vertices)[*,
>> cuts[partn]:cuts[partn+1]-1] )
>> oGon = OBJ_NEW('IDLgrPolyline', (*ent.vertices)[*,
>> cuts[partn]:cuts[partn+1]-1] )
>> oGon -> SetProperty, COLOR = [ 034, 139, 87 ] ; Forest Green
>> oModelSHP -> ADD, oGon
>> ENDFOR
>> ENDIF ELSE IF ( ent.n_parts EQ 1 ) THEN BEGIN
>> oGon = OBJ_NEW('IDLgrPolygon', (*ent.vertices) )
>> oModelSHP -> ADD, oGon
>> ENDIF ELSE BEGIN
>> ENDELSE
>> oSHP -> DestroyEntity, ent
>> ENDFOR
>> OBJ_DESTROY, oSHP
>> ENDIF ELSE BEGIN
>> ENDELSE
>
>> END
>> ;+
>> ;
>> ;
>> ;----------------------------------------------------------- -----------
>> PRO Test_PolyShp
>
>> COMPILE_OPT DEFINT32, STRICTARR
>
>> CountryModel, oModelCntry
>> XOBJVIEW, oModelCntry
>
>> ;WARNING: Big time memory leak
>> ;Do IDL> HEAP_GC, /Verbose
>
>> END
>
> IDLgrPolygons need to be convex in order to render properly. (This is
> the case for the underlying OpenGL as well)
>
> I'm guessing that is what you mean by "leak". Drawing non-convex
> polygons with grPolygon can sort of look like a leak.
>
> It does not look like your code takes any steps to ensure that the
> polygons are convex. It may be the case that your database consists
> of only convex shapes, but I don't know that.
>
> To solve this, look at IDLgrTesselator. It will take an arbitrary
> input polygon and emit a covering set of triangles that can then be
> stored in IDLgrPolygon.- Hide quoted text -
>
> - Show quoted text -
Thanks Karl,
This is what I was looking for. Apparently, there are "holes" in the
vertices and it appears IDLgrTesselator will help close them up.
Kelly Dean
Fort Collins, CO
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