Article	41023378
Type	HowTo
Product	Engine
Version	4.1.6.1028
Date Added	1/13/2004
Submitted by	Mario Pellegrino
Keywords

Subject

Calculate the right centerpoint with Geom3pointCenter

Summary

RetVal = vdraw.Utility.geom3PointCenter(PuntoIniArco, PuntoIntermedio, PuntoFinArco, CentroTmp)

with points in the plane XY

PuntoIniArco= (449,524,0)
PuntoIntermedio=(595,2083,0)
PuntoFinArco=(636,2089,0)

CentroTmp is correct (909,1267,0)

while with points in plane XZ

PuntoIniArco= (449,0,524)
PuntoIntermedio=(595,0,2083)
PuntoFinArco=(636,0,2089)

CentroTmp is not computed correct!!!!!

Solution

See the Visual Basic 6 sample code below:

Dim PuntoIniArco As Variant
Dim PuntoIntermedio As Variant
Dim PuntoFinArco As Variant
Dim retval As Variant
Dim CentroTmp As Variant
Dim extrusion As Variant
Dim matrix As vdmatrix
Dim pt As vdxyz

 PuntoIniArco = Array(449, 0, 524) 'the points are in WCS
 PuntoIntermedio = Array(595, 0, 2083) 'the points are in WCS
 PuntoFinArco = Array(636, 0, 2089) 'the points are in WCS
 
extrusion = VDPro1.Utility.GetExtrusionVector(PuntoIniArco, PuntoIntermedio, PuntoFinArco)
Set matrix = VDPro1.CreateInstance(OBJ_MATRIX)
'where ecs is the coordinate system that defined from three points of arc
matrix.ExtrudeMatrix extrusion(0), extrusion(1), extrusion(2) 'create a matrix to transform from ECS to WCS
matrix.Inverse 'set the matrix to transform from wcs to ecs
Set pt = VDPro1.CreateInstance(OBJ_XYZ)

pt.Value = PuntoIniArco
pt.Transformby matrix
PuntoIniArco = pt.Value 'the point now is in ECS

pt.Value = PuntoIntermedio
pt.Transformby matrix
PuntoIntermedio = pt.Value 'the point now is in ECS

pt.Value = PuntoFinArco
pt.Transformby matrix
PuntoFinArco = pt.Value 'the point now is in ECS
 
retval = VDPro1.Utility.geom3PointCenter(PuntoIniArco, PuntoIntermedio, PuntoFinArco, CentroTmp)

'the center is in ECS so we have to transform it to WCS

pt.Value = CentroTmp
matrix.Inverse 'set the matrix to transform from ECS to WCS
pt.Transformby matrix
CentroTmp = pt.Value

MsgBox CStr(CentroTmp(0)) + " " + CStr(CentroTmp(1)) + " " + CStr(CentroTmp(2))