|Message: Re: problems with BREPS||Not Logged In (login)|
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Hi Nika, > I have a couple of questions concerning BREP Solids construction. > > Browsing through the forum and User Manuals I saw several warnings that > BREPS are not fully implemented. I managed to construct a solid using > G4BREPSolidPolyhedra and it worked. However, when I tried to construct a > G4BREPSolidCylinder and visualize it I got a cube(?!) (the code is > attached bellow). > > My first question: Am I doing something wrong? Is the problem only in > visualization (I use Qt) or is just that this class is not implemented > completely? it is a visualization issue, as polyhedrons for most BREPS are not defined and what you see is just its bounding-box. You can try using the ray-tracer for visualizing, that would show you the real surfaces. > My second question: I want to construct a body that looks like a > trapezoid, but with two circular edges and two straight but nonparallel > edges, of thickness z (figure is attached bellow) . So far I > successfully constructed (approximation) of this body, using > G4ExtrudedSolid. Now I want to construct the body with actual circular > edges. I see two options; BREPS or boolean solids. Which method needs > more CPU time? I really want to try and build this body using BREPS. Can > this be done? I tried defining all the surfaces that confine this body > (planes + cylindrical surfaces) but failed. Can you give me some advice > where can I look for examples of BREP construction and if this is > possible? A simple Boolean composition is OK for CPU performance and would not differ much from a BREPs approach. > My third question: When I visualize the body made by G4ExtrudedSolid I > get some lines inside the body (figure attached bellow). I know this is > just a consequence of visualization, but I was wondering if there is a > way to get rid of them. I tried with /vis/viewer/set/edge and > /vis/viewer/set/hiddenEdge commands but the lines are always present. > Even if I draw this body as solid (/vis/viewer/set/style solid). Can you > give me some advice how to make these lines invisible? You should eventually ask this in the visualization forum! Cheers, Gabriele