organicmaps/libtess2
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Merge pull request #28 from mindbrix/reversedFlag

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Add a reversed flag to tessAddContour()
This commit is contained in:
Mikko Mononen 2018-04-18 06:52:36 +03:00 • committed by GitHub
commit 82dd0a3e9e
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 14 additions and 3 deletions
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5
Include/tesselator.h
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@ -118,10 +118,15 @@ enum TessElementType
// TESS_CONSTRAINED_DELAUNAY_TRIANGULATION
// If enabled, the initial triagulation is improved with non-robust Constrained Delayney triangulation.
// Disable by default.
//
// TESS_REVERSE_CONTOURS
// If enabled, tessAddContour() will treat CW contours as CCW and vice versa
// Disabled by default.
enum TessOption
{
TESS_CONSTRAINED_DELAUNAY_TRIANGULATION,
TESS_REVERSE_CONTOURS
};
typedef float TESSreal;

9
Source/tess.c
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@ -629,6 +629,8 @@ TESStesselator* tessNewTess( TESSalloc* alloc )
tess->bmax[0] = 0;
tess->bmax[1] = 0;
tess->reverseContours = 0;
tess->windingRule = TESS_WINDING_ODD;
if (tess->alloc.regionBucketSize < 16)
@ -973,8 +975,8 @@ void tessAddContour( TESStesselator *tess, int size, const void* vertices,
* vertices in such an order that a CCW contour will add +1 to
* the winding number of the region inside the contour.
*/
e->winding = 1;
e->Sym->winding = -1;
e->winding = tess->reverseContours ? -1 : 1;
e->Sym->winding = tess->reverseContours ? 1 : -1;
}
}
@ -985,6 +987,9 @@ void tessSetOption( TESStesselator *tess, int option, int value )
case TESS_CONSTRAINED_DELAUNAY_TRIANGULATION:
tess->processCDT = value > 0 ? 1 : 0;
break;
case TESS_REVERSE_CONTOURS:
tess->reverseContours = value > 0 ? 1 : 0;
break;
}
}

3
Source/tess.h
View file

@ -62,7 +62,8 @@ struct TESStesselator {
TESSreal bmax[2];
int processCDT; /* option to run Constrained Delayney pass. */
int reverseContours; /* tessAddContour() will treat CCW contours as CW and vice versa */
/*** state needed for the line sweep ***/
int windingRule; /* rule for determining polygon interior */