int main(int argc, char *argv[])
{
//Create a circle like before
gp_Pnt centerPoint(2.5,2.5,0);
gp_Dir normalDirection(0.0,0.0,1.0);
gp_Dir xDirection(1.0,0.0,0.0);
gp_Ax2 axis(centerPoint,normalDirection,xDirection);
//Creating the circle
gp_Circ circle(axis,2.5);
Standard_Integer resolution = 20;
//Here, an array of gp_Pnt is allocated, with 500 elements
//Note that the indexing runs from 1 to 500, instead of the
//standard convention of 0-499
TColgp_Array1OfPnt pointsOnCircle(1,resolution);
//Distribute the points and write them out to a file
PointOnCurveDistribution::distributePointsOnCurve(circle,pointsOnCircle,0.0,2.0*PI,resolution);
WriteCoordinatesToFile::writeCoordinatesToFile("chapter3points.txt",pointsOnCircle);
//Sum the area of the small triangles, to get an approximate area
//The for loop builds triangles with two corners on the circumference
//and the center of the circle as third point
double totalArea = 0.0;
for(Standard_Integer i=1;i<=resolution;i++)
{
gp_Pnt firstPntOfTriangle = pointsOnCircle.Value(i);
gp_Pnt secondPntOfTriangle;
if(i != resolution)
{
secondPntOfTriangle = pointsOnCircle.Value(i+1);
}
else
{
//If we are at the end of the array, take the first point
//because of periodicity
secondPntOfTriangle = pointsOnCircle.Value(1);
}
gp_Pnt thirdPntOfTriangle = centerPoint;
//A Handle (like a smart pointer) is built to an array of points
Handle_TColgp_HArray1OfPnt trianglePointsArray = new TColgp_HArray1OfPnt(1,3);
trianglePointsArray->ChangeValue(1) = firstPntOfTriangle;
trianglePointsArray->ChangeValue(2) = secondPntOfTriangle;
trianglePointsArray->ChangeValue(3) = thirdPntOfTriangle;
totalArea += AreaCalculations::calculateTriangleArea(trianglePointsArray);
}
std::cout << "Polygonized area: " << totalArea << std::endl;
std::cout << "Reference area: " << circle.Area() << std::endl;
std::cout << "Error " << fabs(totalArea-circle.Area())/circle.Area() << std::endl;
return 0;
}
Vector2d<int> SimpleDirection::vectorDirection() const
{
return Vector2d<int>(xDirection(),yDirection());
}
