FreeCADView Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0002318 | FreeCAD | Bug | public | 2015-10-29 21:59 | 2015-12-15 13:15 |
| Reporter | nikospap | Assigned To | jmaustpc | ||
| Priority | normal | Severity | tweak | Reproducibility | always |
| Status | closed | Resolution | fixed | ||
| Fixed in Version | 0.16 | ||||
| Summary | 0002318: can't extrude "R" like sketch to solid | ||||
| Description | Freecad can't extrude an R like sketch into a solid. (this bug is probably a duplicate) | ||||
| Steps To Reproduce | Use Sketcer to create a " ? " like sketch. Then join the two legs of " ? " with a " - " like line. Make sure the edges of the " - " line are connected to the legs of the " ? " . (see 1st attachment) Use Part workbench, and try to extrude the sketch into a solid (enable the "Create solid" option). Result: Ok, this is not what you wanted. (see 2nd attachment) | ||||
| Tags | No tags attached. | ||||
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Let's try to refrase the steps to reproduce this bug ----------------------------------------------------- Use Sketcer to create a " C " like sketch. Then join the two legs of " C " with a " - " like line. Make sure the edges of the " - " line are connected to the legs of the " C " . (see 1st attachment) Use Part workbench, and try to extrude the sketch into a solid (enable the "Create solid" option). Result: Ok, this is not what you wanted. (see 2nd attachment) |
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> Freecad can't extrude an R like sketch into a solid. This is not a bug because what you want to achieve is simply not possible. In order to make a solid the algorithm first must find a closed wire where it can create a face from. Extruding that face creates the solid. However, the problem is already that there is no closed wire -- at least not in topologically correct way. In your example the three lines build a "C" and the fourth line starts and ends at the two horizontal lines of the "C" but there are no vertexes. So, the algorithm only finds the "C" as wire which of course is not closed and thus creating a face is not possible. To get a closed wire you must break the top and bottom lines so that there is a vertex in between and the fourth line must be connected to this two vertexes. Now when extruding the sketch with the solid option you get a filled shape. But the result still might be different to what you expect because it removes the edges. This is because the actual result you expect is not a solid. The property of a solid is that every edge is shared by exactly two faces so that the whole object is watertight. |
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>This is because the actual result you expect is not a solid. In other words, the algorithm cannot handle "mixed" objects. In this case, it should at least give an error message. -------------------------- Doing more testing I noticed the following: 1st To get what someone would expect, in our example, you need to create 2 sketches. One with a parallelogram, and then extrude it into solid. One with two separate lines " | | ", extrude them (but not into solid). And then join the two objects. 2nd If you create a sketch with a single line " | " and extrude it into solid, it seems to work. If you create a sketch with two separate lines " | | ", and try to extrude it into solid, you get an error. If you simply extrude them, but not into solid, then it works. Isn't this inconsistent (or a limit of the algorithm)? (if the two separate lines can't produce a solid, then neither should the single line, or any other "open" shape like " C " or " R " ) |
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Hi Nikospap This is not a bug, it appears to be just a failing to understand how FreeCAD and OCC work. What you appear to be asking for can not and should not work. Please discuss all bugs and feature requests on the Help forum first, no matter how sure you are that it is a bug and only create a ticket after others have confirmed its a bug. This way many people see, have an input and possibly learn from the one post. If you would like to post on the Help forum I and others will be happy to explain in detail. :-) Briefly though the output is logical and hierarchical. If you Part Workbench extrude 1) a point you get a line 2) a line you get a face 3) an open wire (series of connected lines) you get an open shell (series of connected faces) 4) a closed profile wire you get a closed shell with the option to convert it into a solid 5) a face you get a solid Mixtures of the above should only be made with separate extrudes. Trying to extrude from a mixed source creates a potentially undefined situation that should not work and does not work. Trying to do so sounds like just mistaken modelling practice. Please post on the Help forum with details about what you are trying to achieve and we will be able to help you resolve the matter. :-) For now I will close this ticket, I/we can reopen it after a discussion on the Help forum, if needed. Jim |
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closed, this is not a bug, it is expected behaviour. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2015-10-29 21:59 | nikospap | New Issue | |
| 2015-10-29 21:59 | nikospap | File Added: extrude_an_R_like_sketch_001.jpg | |
| 2015-10-29 22:00 | nikospap | File Added: extrude_an_R_like_sketch_002.jpg | |
| 2015-10-29 22:04 | nikospap | Note Added: 0006510 | |
| 2015-10-31 17:31 | wmayer | Note Added: 0006511 | |
| 2015-10-31 17:31 | wmayer | Status | new => feedback |
| 2015-11-01 10:43 | nikospap | Note Added: 0006513 | |
| 2015-11-01 10:43 | nikospap | Status | feedback => new |
| 2015-11-04 05:52 | jmaustpc | Note Added: 0006525 | |
| 2015-11-04 05:53 | jmaustpc | Note Added: 0006526 | |
| 2015-11-04 05:53 | jmaustpc | Status | new => closed |
| 2015-11-04 05:53 | jmaustpc | Assigned To | => jmaustpc |
| 2015-11-04 05:53 | jmaustpc | Resolution | open => fixed |
| 2015-12-15 13:15 | yorik | Fixed in Version | => 0.16 |
