Early version of the vanishing point assistant:
You lay down three of them, and each gives a preview, resulting in help for a 3-point perspective. Snapping doesn't work yet.

Thoughts:
*Needs a marker in the UI.
*Might create an option that all assistants can optionally have a number between 0 and 360 to create a coloured line around it, because now they're a little difficult to read?
*Will need to investigate how to create extra knowbs, so someone might adjust the ruler to the existing perspective.
*Parallel ruler becomes very desired after a while.

Alright: vanishing point, parallel and infinite ruler assistants are under review: https://git.reviewboard.kde.org/r/121256/

Edit: pushed!

I was thinking about the style of this and it might be a good idea to make all of the assistants consistent. This includes the following:

horizontal mirror tool
vertical mirror tool
multi line tool
Ruler assistants ( vanishing point, ellipse, spline, perspective, parallel ruler, ruler, infinite ruler)

My thought would be to make the lines all dotted, and make the handle things have a white background, with a grey icon in it (like the image below)

Hi Wolthera,
I am loving the Vanishing Point rulers (or helpers). Makes setting up perspectives super easy. So first of all, THANKS.
I have some comments/questions about the new rulers, hope you can shed some light on them,

* Shud I use the Infinite ruler for a Horizon line or a regular ruler? I am getting better results with Infinite

free photo hosting
INFINITE


screen shot
RULER

* When the previews are switched off the snapping stops working, sometimes the previews get a little distracting
* The small mountain peaks where the snapping seems to get confused between two rulers, can we get rid of them, I mean in future

Yes, previews and snapping are linked to the same eye-icon now. You can turn off previews globally via view->show assistant previews, without turning off snapping (the hide paintings assistants is not supposed to hide previews, but due to a merge bug it does, it'll be fixed).

The confusing of the snapping is something that at the moment I can't do much about. I can try come up with better solutions, but it's rather a problem inherit in the design, and it'll take a while to get around that. (After all, if they were easy to get rid off, I would've done it already...)

I don't think you really need a ruler for the horizon in a two-point perspective. After all, the horizon is the line between the two vanishing points, so just draw a line from one vanishing point to the other, bam, instant horizon

In general though, I don't personally use snapping a lot(I just need to know where the VPs are), I'm hope this is not held against me.

EDIT: Basically, the problem is that the assistants don't know the other exists, and the snapping is done by determining the current input mousepoint and comparing it to valid points according to the active assistants. The closest valid point is the one the brush snaps to. So if you attempt to draw straight lines it works, except for when the two rulers are too close.

I generally have little opinion about UI appearance, but scott already knows this.

TheraHedwig wrote:You can turn off previews globally via view->show assistant previews, it already...)

Cool I will look into this.

As a little celebration that my exams are over... sort of(still need to do resits), I did a warm up with a concentric ellipse ruler. It's in the 2.9 branch, so it should be in any given new build

i'll wait for a new build to be announced before i try, but looks great! congrats.

Thanks for concentric circle Wolthera.
it is really helpful.

I tried to do a fish eye perspective by placing the Vanishing point at the center of concentric ellipse and having a parallel ruler, but I think I need to think of another method its not perfect take a look at the setup.


thanks again for the assistant I am having fun playing with it

That's because fish eye perspective needs a whole different type of lines. It's not concentric lines, but rather splines being interpolated from a straight middle to highly curved extremes.

I made an example:

(photo from here: http://adaptivesamples.com/2013/11/17/h ... nt-images/ (cc-by-sa) )

People don't realise this, but the fish eye lens type of perspective also applies to environment maps, hence I picked an environment map to illustrate it.



The first thing you need to realise, to understand perspective deformation at all, is that it hinges on what parallel lines do in this space.
An orthographic projection is where all the parallel lines in the 3d space are parallel to each other, are also parallel in the 2d space.
In a linear perspective, those parallel lines that move away from the viewer, meet each other in a vanishing point.
In a fish lens perspective however, you need to think of what happens when you look at parallel lines that are parallel to your position, and what happens where they go 'off' screen. They meet up in both sides at vanishing points.

But that same thing also counts for parallel lines at a 90 degree angle to the earlier mentioned ones. Those too have 2 vanishing points. That loop.

So, to draw a panorama like the enviroment map, you need two vanishing points, and generate a third one that is actually one of the other vanishing points, but then looped around to... I dunno if this makes sense.
Then, we would want a third node to draw the extremity of the deformed parallels. (before they break up at the top).

My biggest issue right now is that I can't really think up of an 'alignment' method like I did with the vanishing point ruler. Then comes me deciding how I am going to do the maths to do the interpolation of the deformation of the curves...

Sad thing is, this is all still easier than parallel spline

Edit:
Part of me is wondering whether it makes more sense to set up the vanishing points, or to set up the undeformed center, a vanishing point and an extremity and generate the rest from there...
There would be a same amount of nodes, but I dunno what is most convenient to use?

Edit2: Actually, looking at it I could use sinus formula instead of splines...

I bashed my head against the Fish Eye Point Assistant today...
https://phabricator.kde.org/D117



It still needs a lot of (usability) work, but I put the patch on review board for the curious.

hmm, looks like neither of these are in 2.9.5 ? ( I also thought the selections stuff would be there)

nharmony wrote:hmm, looks like neither of these are in 2.9.5 ? ( I also thought the selections stuff would be there)

Nope, I thought the next release would be 2.9.5.1 because we were holding back 2.9.5... but turns out we were holding it back for no reason...

*single tear runs down cheek*

I'll be home next week and do new packages on Wednesday That's the earliest you'd have been able to get them anyway!