PGPOLYEXT data type

[Danny Sparks-Cousins]

Hi all,

I want to use some of the geometry functions;

Geometry::PGPolyAreaExt
Geometry::PGPolyPositionExt

To find area & polygon position status for two polygons.

I have the 2 polygons as type Polygon2Ddata. Can anyone explain how to convert from Polygon2Ddata to PGPOLYEXT type?

Any ideas would be appreciated.

Cheers,
Danny

[Tibor Lorantfy]

Hi Danny,

Here's a short example code for you to convert Polygon2Ddata to PGPOLYEXT:

GSErrCode Convert_Polygon2DData_To_PGPOLYEXT (const Geometry::Polygon2DData& 	polygon2DData, 
																Geometry::PGPOLYEXT*			pgPOLYEXT) 
{ 
	if (&polygon2DData == NULL) 
		return ErrParam; 
 
	BNZeroMemory (pgPOLYEXT, sizeof (Geometry::PGPOLYEXT)); 
 
	// here comes a little bit ugly cast 
	pgPOLYEXT->data = reinterpret_cast<GSPtr> (const_cast<Geometry::Polygon2DData*> (&polygon2DData)); 
 
	// Perhaps you need to set some other attributes too: 
	//  pgPOLYEXT->status.isSameDirEdgeLegal = polygon2DData.status.isSameDirEdgeLegal; 
	//  pgPOLYEXT->epsilon = SMALLEPS * 8; 
	//  pgPOLYEXT->minVertexDist = 3 * pgPOLYEXT->epsilon; 
 
	return NoError; 
} 
 
/* --------------- Usage example: -------------------------- */ 
 
Geometry::Polygon2DData 	polygon2DData;
Geometry::PGPOLYEXT 		pgPOLYEXT;
 
Convert_Polygon2DData_To_PGPOLYEXT (polygon2DData, &pgPOLYEXT);

Sorry, I've never tried that, but it seems correct.

Regards,
Tibi

[Danny Sparks-Cousins]

Excellent - thanks Tibor

[Danny Sparks-Cousins]

OK - I havent quite got my head around how to use the PGPOLYEXT data and functions.

I have a need to perform some operations on two existing zones - from the documentation it looks like the following functions would work well for what I need;

PGPolyUnionExt to combine two different zone polygons
PGPolyIntersectionExt to intersect two different zone polygons
PGCoordInPolyExt to check if a point is within a zone polygon
PGPolyAreaExt to calculate the area of the PGPoly results

I am having trouble doing anything with PGPOLYEXT data at all though. I tried Tibor's example to convert a simple Polygon2DData to PGPOLYEXT but still couldnt get actual results even from PGPolyAreaExt.

Am I on the right track in using this data type and these functions for what I want to achieve with the zone polygon data? If anyone has some thoughts and ideas to step me through that would be greatly appreciated - or even some very simple example using polygon data and PGPOLYEXT data functions?

Thanks,
Danny

[Danny Sparks-Cousins]

Bump.

Does anyone have any thoughts about this, or used the PGPOLYEXT functions?

[Tibor Lorantfy]

Hi,

if you want to get the area from your Polygon2DData, you don't have to convert it! Sorry if I was misleading.

You can use the following function:

double Geometry::GetPolygon2DDataArea (const Polygon2DData& polygon2DData, bool isPolyLine = false);

For example:

double area = Geometry::GetPolygon2DDataArea (myPolygon2DData);

To find more geometry functions with Polygon2DData see the Polygon2DData.h header file in the DevKit's Support\Modules\Geometry\ folder.

Regards,
Tibi