How to create a Box TopoDS_Solid in OpenCASCADE

Also see How to create a Cube TopoDS_Solid in OpenCASCADE and How to create a Cylinder TopoDS_Solid in OpenCASCADE

Using my OCCUtils library, you can easily create a box of user-defined dimensions:

#include <occutils/Primitive.hxx>
#include <vector>

using namespace OCCUtils;

TopoDS_Solid myCube = Primitive::MakeBox(5.0 /* X size */, 7.0 /* Y size */, 9.0 /* Z size */);

You can also center this box on one or more axes (if not centered in any axis, one of the corners is going to be on thre origin point):

#include <occutils/Primitive.hxx>
#include <vector>

using namespace OCCUtils;

/*
 * Make a box that is centered on the X- and Y axes
 */
TopoDS_Solid myCube = Primitive::MakeBox(5.0, 7.0, 9.0
    Primitive::CenterX | Primitive::CenterY);

Also you can use a specific point of origin as the third argument (gp_Pnt).

If you want to do it manually without OCCUtils, have a look at the OCC class BRepPrimAPI_MakeBox which you can use like this:

BRepPrimAPI_MakeBox box(origin, xSize, ySize, zSize);
box.Build();
TopoDS_Solid mySolid = box.Solid();

In this case, you have to center the object manually by computing the correct point of origin. In OCCUtils this is done using

// Compute offsets based on centering
if(center & CenterX) {
    origin.SetX(origin.X() - xSize / 2.0);
}
if(center & CenterY) {
    origin.SetY(origin.Y() - ySize / 2.0);
}
if(center & CenterZ) {
    origin.SetZ(origin.Z() - zSize / 2.0);
}