2
$\begingroup$

The knife tool or knife project tool cannot be applied on the faces shown in the screenshot, but they worked on other faces. I've used 'remove doubles' and 'recalculate normals' on my model but that doesn't solve the problem. Any help is appreciated :)

Model Download Link : Here (A circle was placed in front of these faces for knife project tool testing)

enter image description here

$\endgroup$
  • 2
    $\begingroup$ What is that face just below the top one as seen here ? It seems like it shouldn't be there, because the bottom selected face has common edge with the one extruded outwards. Also all this would be a lot easier if you upload a file (at least only this problem part).. $\endgroup$ – Mr Zak Jul 28 '15 at 17:06
  • $\begingroup$ I have added a link for downloading my model. $\endgroup$ – Mr.Benson Jul 29 '15 at 6:59
  • $\begingroup$ I don't know if this is a bug or not, it might not be intended to cut on mirrored geometry.. maybe someone else can confirm - else we can do a bug report $\endgroup$ – zeffii Jul 29 '15 at 11:57
3
$\begingroup$

It appears to be because you are trying to cut into the "virtual" geometry created by the mirror. You have set the Mirror modifier to display both sides as if they as edit-able, but the KnifeProject feature doesn't seem to take the mirrored geometry into account (but it is reasonable to expect that it should..)

enter image description here

the option with the green square let's you edit both sides, but not project onto both sides.

enter image description here

enter image description here


Other problems with your model:

You also have some issues with degenerate geometry (faces with zero area), and faces that you might not be aware of causing non-manifold geometry. Use

enter image description here

to look for hidden geometry, and in Face selection mode look for Dots on Edges, that's an indication that you have collapse or potentially "invalid" geometry.

enter image description here

Additionally, the KnifeProject tool has a feature which can limit/extend the distance the cut goes into the geometry.

enter image description here

Is the different between these two cuts (cut from a different Viewing angle than shown so you can see the range of the cut)

enter image description here

$\endgroup$
  • $\begingroup$ I can't thank you more for writing this detailed answer! I have removed a few hidden geometry. But I found out the real problem is that knife project tool can't be used on more than two connected faces (for my case). Anyway thank you so much for your help! :D $\endgroup$ – Mr.Benson Jul 29 '15 at 14:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.