How to get the projected area through API function？

leilei — Wed, 30 Nov 2022 09:47:56 GMT

Hi,

Does anyone know this question?If I have a 3D object and I want to get the projected area of this object, is there any way to get this area through the API function?

Best regards,
Leilei

Re: How to get the projected area through API function？

Ralph Wessel — Thu, 23 Aug 2018 06:28:53 GMT

Could you clarify whether you mean the total surface area of the 3D body or the area visible in the 3D window?

Re: How to get the projected area through API function？

leilei — Thu, 23 Aug 2018 06:40:05 GMT

Ralph wrote:
Could you clarify whether you mean the total surface area of the 3D body or the area visible in the 3D window?

Hi Ralph,
The area I want is like a projection on a floor plan.
Regards,
Leilei

Re: How to get the projected area through API function？

Ralph Wessel — Thu, 23 Aug 2018 07:10:20 GMT

I don't know if there's an easy answer to that. Bottom line, you could extract the faces of the 3D body, project them to 2D polygons in the view plane and merge them to result in the bounding polygon(s). Hopefully there is a simpler method.

Re: How to get the projected area through API function？

Tibor Lorantfy — Thu, 23 Aug 2018 07:40:13 GMT

Ralph's right, you have to calculate this on your own.
But of course we are here to help you, so I wrote you a draft for this calculation:

#include	"ACAPinc.h"

#include	"basicgeometry.h"
#include	"Polygon2D.hpp"

static double CalculateProjectedAreaOfElem (const API_Guid& elemGuid)
{
	double			calculatedArea = 0.;
	GSErrCode		err = NoError;
	Geometry::Plane	floorPlanPlane;
	API_Elem_Head	elemHead = {};
	elemHead.guid = elemGuid;

	API_ElemInfo3D 	info3D;
	err = ACAPI_Element_Get3DInfo (elemHead, &info3D);
	if (DBERROR (err != NoError))
		return 0;

	Geometry::MultiPolygon2D projectedPolygon2DArray; 
	for (Int32 ibody = info3D.fbody; ibody <= info3D.lbody; ++ibody) {
		API_Component3D 	component = {};
		component.header.typeID = API_BodyID;
		component.header.index  = ibody;
		err = ACAPI_3D_GetComponent (&component);
		if (DBERROR (err != NoError))
			continue;

		Int32		nPgon = component.body.nPgon;
		API_Tranmat	tm = component.body.tranmat;

		for (Int32 iPgon = 1; iPgon <= nPgon; ++iPgon) {
			component.header.typeID = API_PgonID;
			component.header.index  = iPgon;
			err = ACAPI_3D_GetComponent (&component);
			if (DBERROR (err != NoError))
				continue;

			GS::Array<Coord>	pgonCoordsProjectedToFloorPlan;
			for (Int32 iEdge = component.pgon.fpedg; iEdge <= component.pgon.lpedg; ++iEdge) {
				component.header.typeID = API_EdgeID;
				component.header.index  = iEdge;
				err = ACAPI_3D_GetComponent (&component);
				if (DBERROR (err != NoError))
					continue;

				component.header.typeID = API_VertID;
				component.header.index  = component.edge.vert1;
				err = ACAPI_3D_GetComponent (&component);
				if (DBERROR (err != NoError))
					continue;

				Geometry::Coord3D	worldCoord;
				worldCoord.x = tm.tmx[0]*component.vert.x + tm.tmx[1]*component.vert.y + tm.tmx[2]*component.vert.z + tm.tmx[3];
				worldCoord.y = tm.tmx[4]*component.vert.x + tm.tmx[5]*component.vert.y + tm.tmx[6]*component.vert.z + tm.tmx[7];
				worldCoord.z = tm.tmx[8]*component.vert.x + tm.tmx[9]*component.vert.y + tm.tmx[10]*component.vert.z + tm.tmx[11];
				Geometry::Coord3D	projectedCoord = floorPlanPlane.ProjectToPlane (worldCoord);
				pgonCoordsProjectedToFloorPlan.PushNew (projectedCoord.x, projectedCoord.y);
			}

			Geometry::MultiPolygon2D polygon2DArray; 
			Geometry::Polygon2D::Create (pgonCoordsProjectedToFloorPlan, 0, polygon2DArray);
			projectedPolygon2DArray.Append (polygon2DArray);
		}
	}

	projectedPolygon2DArray.Unify (Geometry::WithoutHoles);
	for (const Geometry::Polygon2D& polygon2D : projectedPolygon2DArray)
		calculatedArea += polygon2D.CalcArea ();

	return calculatedArea;
}

This is based on Ralph's idea.

Re: How to get the projected area through API function？

leilei — Thu, 23 Aug 2018 08:14:01 GMT

Thanks Ralph and Tibor,

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How to get the projected area through API function？

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Re: How to get the projected area through API function？