Extruding edges at an Angle in Blender

[Ciaran Laval]

I'm making a roof, so I start with this:

Then I want to have the edges overhang to the sides and front and back, the front and back part isn't too complicated, but the sides are annoying me.

Now I've done that by extruding the faces and then when it comes to the sides, rotating by 45 degrees, but the angle isn't quite right.

I'm pretty sure that I should be able to delete the side faces, extrude the edges at the correct angle and then create a new face to finish it off, but I cannot remember how to do this, i recall something about pressing e twice and going into local mode, but it doesn't seem to be working now.

The front and back I'd rather just slide the triangle back, rather than extruding the faces, although it's not that important,  I'd rather avoid unnecessary edges if I can and keep it cleaner.

Is there a way of extruding edges at the correct angle, I swear I've done this before, but I'm getting old now, maybe my memory is playing tricks on me.

[Ebrech Aridian]

Reminding you of some tricks to use,

Do only half, create a Mirror modifier, make sure your Origin is set to the middle.

on the Mirror Modifier, make sure that merge and clipping are turned on.

then extrude and rotate to the angle desired,

On the Transform Orientation menu at the bottom, make it to Normal instead of Global, This way you can reselect the face of your extruded angle, and move it along a straight line of the same direction.

When the two mix they will merge and give you a nice look, then apply the modifier in Object mode and delete the face inside your middle junction (useless face anyway)

You could also just use the Grid, with Snap activated and make only a simple line drawing Vertices by Vertices.

To do so, make a plane, delete 3 verts, and use only the last one, then you extrude by pressing one of these after the E (X,Y,Z) to make sure it goes on the right direction, when you are satisfied, you can press F to fill the form, or create more verts with Subdivide, and make quad faces, you should leave the triangle face out until the end, and when you are done always make sure to Recalculate, and remove Doubles.  

 

PS: A quad is a face with 4 verts.

 

Hope that will help you.~!

 

 

[Ciaran Laval]

I have never used the mirror modifier but I'm seeing it mentioned a lot so I really need to try it out. Thanks a lot for the tips.

[Rahkis Andel]

I think the tip you were thinking of is that if you hit a transform tool and press x y or z to lock it to an axis, it will lock it to the global axis first and if you press it (x y or z) again, it will lock to the local axis, which may give you a different result. Hopefully I didn't mix those up, but you get the idea.

[Aquila Kytori]

hi

E (to extrude) , validate, then  to move the new face, validate.

        is not the same as:

E (to extrude), move new face, validate.

  The first will allow you to move the face anywhere in the 3D view while  the second will restrict the movement to along the face normals.

[Ciaran Laval]

Yes thank you, that was it, press the axis you want to move along twice. Not working, I'm missing a trick or two here I swear I could do this at one stage.

The other approach I'm looking at is creating new vertices and doing it that way, I can subdivide an edge and slide the vertex along an edge by scaling it, but in terms of accuracy of position it's not great, although the vertex moves along the angle I want it to move along very nicely.

[Ciaran Laval]

Thanks I'll take a look at that again later.

[Rahkis Andel]

I have edited my post because the end of it was rubbish. I didn't really explain it properly and I've remembered the "right" way to do it.

As Aquila pointed out, extrude is two functions; First the selection is extruded and then placed into translate mode with the orientation being locked to the normal z axis. That moves the selection along their average normal direction only.

You can get that same behavior without extruding first:

All you have to do is open your viewport properties panel (n) and scroll down to the transform orientations tab. It is set to "global" by default. This produces the behavior you know now, which is you enter a transformation mode and press x, y or z once to lock your transformation to that global axis and press it again to lock to the local axis.

You get the same behavior by switching the transform orientation to "local". Either way, it just toggles between global and local. If you set the orientation to "normal", however, the second time you press x, y or z it will lock it to the face normals.

Specifically, normal orientation takes the face normal direction, or average normal direction of all selected faces and sets the z axis to that. So if you want to scale, rotate or translate along the face normal direction, you want to lock it to the normal z axis.

if you select a face and press (alt+s), that has the same behavior as scaling along the normal z axis. That is a really useful hotkey for inflating your mesh after several smooth operations because you tend to lose a lot of volume. I'm surprsised there is no such hotkey for move and rotate -- perhaps they just aren't as often used.

Personally, I often need to move faces along their normals in architectural modeling, so I'm glad I remembered this method.

[Rahkis Andel]

To expand on that last post, here's a roof demo to illustrate how nice the transform orientation panel is. You can actually create your OWN transform orientations which set the z axis to the normal direction of any face you select.

Here is how I would recreate your roof:

I started with half of a cube on a 45 degree angle and extruded the top faces up.

At this point, i have the same issue as you; If I wanted to extrude an overhang, it would extrude along the normal direction of that face, which in this case is not the direction I want.

I selected the face opposite of the direction I wanted to extrude, because that one was oriented in the correct 45 degree angle.

In my viewport properties panel in the Transform Orientation tab, I pressed the (+) button next to "global".

Then selecting a new orientation from the dropdown, you will notice "face" is now an orientation. If you select that orientation, you can then rename it as you wish.

Then I extrude (e) and immediately right click to cancel the move operator, because it will still be going in the normal direction.

I then move (g) the face lock it to the "face" z axis (z -> z).

And so now I have the desired overhang and can do the same with the other side. You would just use the opposite side of the roof to grab the orientation for that 45 degree angle. You can have as many orientations saved as you like and you can delete them by pressing the (x) button in the transform orientations tab.

Hopefully this demo gets you exactly what you wanted.

Cheers.

Edit: Come to think of it, I didn't need to select the opposite side of the roof to get the correct angle. Since I wanted a transformation perpendicular to the 45 degree slope of the roof, I could have just locked the transformation to the x "face" orientation instead of z.

[Nacy Nightfire]

 

If you are trying to extend the roof so  that the extension terminates flat in the z direction, an easy way to accomplish this is to go into object mode and select the roof.  Press control A to zero out it's rotation, location and scale.  

 

While still in object mode rotate the roof 45 degrees* and return to edit mode.  Select each edge and extrude it along the global axis it follows.    Return to Object mode and press ALT R to snap the roof mesh position back to where you stored it.

 

(I use custom transforms all the time, but for something this simple it's easy just to rotate the mesh in object mode then edit  it and return to object mode using Alt R to snap it back to position.)

 

*or whatever degree is necessary to line things up with the global axis for an edge you want to extend.

[Rahkis Andel]

That's a good idea too. There's actually a ton more ways to do this, but that's the beauty of it all, right?

Edit: Come to think of it, I don't really think having to tilt the roof either way is saving you time. Create one new orientation and lock to face z and x axis respecitively. There was only one extra button press.

[Nacy Nightfire]

I agree Rahkis, the method I suggested doesn't really save time, except that it's a "no brainer" method to accomplish the task.  Also I think it gives a different result on the orientation on the ends of the extensions that appears different from your method.  Both are great solutions and its nice for folks to be exposed to as many methods as possible for this type of task.  

 I personally like to "break things up a bit" and use alternative methods to keep things from being too tediously dull while modeling as all these 3d programs offer many ways to do each single thing and we have the good fortune to adopt our favorites. For me my preferred way to do something can change over time so I enjoy learning ALL the options.  So yes that IS the beauty of it!

(and if you have other ways  please share! although I don't want to hijack the thread here with the suggestion, but this is a basic skill that alot of people starting out can benefit from learning about).

[Ciaran Laval]

Thanks for all the replies and one tip to add to all the ones here, check the angles of your faces before rotating anything, the reason the rotation looks a tad odd when I use rotation on the extruded faces is because the angles weren't what I assumed they were .... which was rather silly of me considering there's a tick box to turn face angles on!

[Arduenn Schwartzman]

Hi Ciaran,

By building at 45° angles for movin roof edges and then rotating back 45°, you'll get quite far. Also, the use of the knife tool (press 'k' in blender, hold ctrl while clicking on edges and end your selection by pressing 'enter' (not return). The result would be like this:

However, your strategy has two disadvantages:

1. There are no inside walls yet.

2. This roof will cost you 30 triangles to upload and will have a larger land impact than the alternative design:

14 Triangles, including inside walls

[Nacy Nightfire]

Ooo good tip about holding down ctrl while using the knife tool , thanks!