edgeloop = clip tool
and since brushes are convex volumnes defined by planes, you wont ever have ability to freely create new edges like in polygonal modelling

extrude = clone+drag for planar faces

for non-planar its not that simple
and actually this could be doable new editor feature: draw new brush based on a selected face and normal 

which could be a very feature useful to have.

eg. boxing out rooms and the using the clip tool to cut out the doors. Just do 3 quick splits and remove the unwanted brush. Do another split above the door for instant trim... Could allow for speedy mapping in combination with csg-hollow.

Implementation could be hitting shift+return instead of just return. Or something among those lines. 

Okay, tab works like magic. Lol.
Think I'm gonna use that a lot.

/noob 

I don't remember getting that error, mine has been working for a month. I do remember that I had to update my graphics card drivers to the latest version to solve the problem I had. (I was using a fresh out-the-box install of Windows 8) 

Isn't this what you mean: https://github.com/kduske/TrenchBroom/issues/418 

Yeah, FifthElephant, it was one of the first 25 posts of this thread. Google remembers.

SleepwalkR, yah, vcredist_x86.exe works now.

Spiney, now I know you didn't watch my trenchbroom video on clip. :)

---

Extrude could be powerful, and therefore seems worth it for the programmer to make it. However, I disagree with edge loop.

EdgeLoop though seems like a feature for lazy people that couldn't just simply just press C and clip several times, therefore wouldn't be worth it to the programmer to make this.

Also, it's probably not often you'd use this feature anyways.

But since Clip already exists, then I suppose it would be somewhat easy for the programmer to take that and make an EdgeLooping function. 

Edgeloops don't split the brush - they add an edge loop. Don't call people lazy when you don't even understand what's being proposed. 

What exactly is it? Is there a video somewhere? 

This covers the Max version pretty well:

https://www.youtube.com/watch?v=3rJdMLmQRiE

It's a standard modeling tool. I'm not saying it's something that TB needs but I took issue with it being called the same thing as a clip. It isn't. :) 

In a world of quake bushes it is essentially a clip tool. The edges are planes intersections, you cant have overlapping planes of the same brush. 

This is why I said that it wouldn't work in TB as it's currently coded because the added edgeloop would be optimized away the frame after it was created. The only way edgeloops are useful is if TB will leave the brush alone until some point when the user "commits" the change.

It's probably more work than it's worth, to be honest.

But it's not a clip tool. :) 

And yes clipping is different, but it serves the same practical purpose. 

flipping edges would be interesting, but i'm not sure how that could be done in TB since each brush exists on it's own independently of it's neighbours. 

You guys have to remember that I'm not familiar with any 3D modeling package ;-) 

Basically, if you have a quad broken into 2 triangles, edge turning turns the quad so the triangles from the other corners.

So

|/| becomes |\|

Useful for correcting shading and lighting errors on 3D stuff. 

Since TB merges coplanar faces automatically, it doesn't seem to be useful. 

@ the extrude image: Yeah, that was about what I meant. Pull the new brush out along the face normal. Usually followed by moving the "new" vertices to where one wants them, then extruding again (typically used for quickly blocking out shapes, like for example curves).

Edge loop is clip:

Not quite. In terms of brushes, it would do much the same thing, but clip isn't as user friendly or intelligent.

If you can make the clip tool able to do multiple parallel clips in one go, and intelligently choose the clipping plane according to the position of the mouse cursor and keep all the new brushes after the clipping, and let you slide the clipping plane(s) along the brush with the mouse, then it might get close.

slapmap: Anything that speeds up the workflow is a good idea, IMO.

It's up to Sleepwalker if he considers any of this useful, of course.

Regarding edge turning, it would probably also give the mapper some control over which way the quads are split in the BSP process. For outlying terrain at least. Smooth triangle strips, all tris going the same direction, render faster, afaik. But then, inside a complex map, this wouldn't be enough to control the splitting, of course. Now if you had triangle terrain and you turned it into detail brushes, then you might be able to influence the splitting. 

Sorry, yes it's what Willem said, however, there is an application for it in TB.

You have 2 brushes with 2 adjacent 3 sided faces forming a 4 sided surface. The 2 3 sided faces are not coplanar.
You want to change the split between the two brushes while preserving the position of the vertices: http://necros.fov120.com/temp/trenchbroom/edgeTurning.jpg 

I think this would be useful on a terrain mesh. Using it would flip the dividing edge between two triangular brushes, which allows you to smooth out surface geometry of a terrain without adding more tris, but simply by optimising the flow of the edges in the mesh.

http://openmesh.org/Documentation/OpenMesh-2.0.1-Documentation/mesh.flip.png

I often do this manually when modifying terrain in Worldcraft. Terrain is about the only place I think I would use it though. 

yeah, it's of somewhat limited use, but where it is useful (terrain), it's powerful.

so it's kind of a toss up really. 

I would definitely like edge flipping. I used in WC also, I can think of more applications than just terrain (though admittedly this is the primary function). 

TB, the clip tool is already pretty smart at choosing a clip plane even if you have only one clip point. And you can split brushes with it, that is, keep both sides. 

Is really good actually, I didn't even use 3 point clipping at first because I never really used it in WC but I'm getting into a good work flow now. 

Yep, clip tool is nice. Clip, clip, and you already have a 4-piece/piece of terrain. Duplicate, duplicate, etc. and you have land of terrain. Drag edge/vertices, and wallah!

FEATURE REQUEST:
For light entities, draw a faint lined circle around the entity in the 3d viewer. The circle is as big as the "light" setting of the light entity. If light = 300, then circle is that big. These circles can be turned on or off.

---

SIDE NOTE:
Double check that the entity panel has the stuff in it from the .fgd or .def file. You know, it shows the description and the available keys for you to use, for that particular entity you're creating. 

That would be a nice feature. Even nicer feature - light simulation.