Hello, please try to use gp_Ax2 instead of (gp_Trsf False 0.0). Just single gp_Ax2
Unfortunatelly, I have no more ideas.
Best regards, Commenter-1.
Archived discussion
Project to 2D
I'd like to project a part to 2D using hidden line removal with HLRAlgo_Projector, but the projection is off and I can't figure out why. I've disabled the perspective transformation and the coordinate system is perfectly top down and it still looks like it's being projected with a perspective. Here's a code snippet (using pyOCCT), and I've attached a screenshot of the generated lines.
Please let me know what needs to be changed to render an orthographic projection of the part.
# Define the transformation for the isometric projection
direction = gp_Dir(0.0, 1, 0)
point = gp_Pnt(0, 0, 0)
coordinate_system_3d = gp_Ax3(point, direction)
# Create a transformation from the coordinate system
transformation = gp_Trsf()
transformation.SetTransformation(coordinate_system_3d)
# Create the projector with orthogonal projection
projector = HLRAlgo_Projector(transformation, False, 0.0)
hlr = HLRBRep_Algo()
hlr.Add(shape.wrapped)
hlr.Projector(projector)
hlr.Update()
hlr.Hide()
hlr_shapes = HLRBRep_HLRToShape(hlr)
Discussion
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Worked! Here's the part I changed:
ax2 = gp_Ax2()
ax2.SetLocation(gp_Pnt(0.0, 0.0, 0.0))
ax2.SetDirection(gp_Dir(0.0, 1.0, 0.0))
ax2.SetXDirection(gp_Dir(1.0, 0.0, 0.0))
projector = HLRAlgo_Projector(ax2)
hlr = HLRBRep_Algo()
hlr.Add(shape.wrapped)
hlr.Projector(projector)
hlr.Update()
hlr.Hide()
Thanks for your help.
Hello, You can check the examples in the document: HLR Examples https://dev.opencascade.org/doc/overview/html/occt_user_guides__modeling_algos.html#occt_modalg_10_1
For exact HLR algorithm, you need HLRBRep_HLRToShape to extract the result.
// Build The algorithm object
myAlgo = new HLRBRep_Algo();
// Add Shapes into the algorithm
TopTools_ListIteratorOfListOfShape anIterator(myListOfShape);
for (;anIterator.More();anIterator.Next())
myAlgo->Add(anIterator.Value(),myNbIsos);
// Set The Projector (myProjector is a HLRAlgo_Projector)
myAlgo->Projector(myProjector);
// Build HLR
myAlgo->Update();
// Set The Edge Status
myAlgo->Hide();
// Build the extraction object :
HLRBRep_HLRToShape aHLRToShape(myAlgo);
// extract the results :
TopoDS_Shape VCompound = aHLRToShape.VCompound();
TopoDS_Shape Rg1LineVCompound =
aHLRToShape.Rg1LineVCompound();
TopoDS_Shape RgNLineVCompound =
aHLRToShape.RgNLineVCompound();
TopoDS_Shape OutLineVCompound =
aHLRToShape.OutLineVCompound();
TopoDS_Shape IsoLineVCompound =
aHLRToShape.IsoLineVCompound();
TopoDS_Shape HCompound = aHLRToShape.HCompound();
TopoDS_Shape Rg1LineHCompound =
aHLRToShape.Rg1LineHCompound();
TopoDS_Shape RgNLineHCompound =
aHLRToShape.RgNLineHCompound();
TopoDS_Shape OutLineHCompound =
aHLRToShape.OutLineHCompound();
TopoDS_Shape IsoLineHCompound =
aHLRToShape.IsoLineHCompound();
Follow up question: Is there any way to get the original faces associated with each extracted edge?
Looking into source code i dont see the options for that.
You can get the original edge for the extracted edge.
Cool! Could you please let me know how to do that?
Sorry, I misunderstand.
You can get the hidden/visible part of shape edges by give the shape to VCompound, HCompound, .etc.
TopoDS_Shape VCompound (const TopoDS_Shape& S);
TopoDS_Shape OutLineVCompound (const TopoDS_Shape& S);
TopoDS_Shape HCompound (const TopoDS_Shape& S);
TopoDS_Shape OutLineHCompound (const TopoDS_Shape& S);