inkscape-devel

 [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Maximilian Albert - 2007-03-24 17:27:00 ```Hi, I am planning to submit a proposal for the 3D box tool as a Summer of Code project. For illustration purposes, I have collected a few ideas and prepared some graphics regarding possible features. This is meant to get across how it would "feel" using the new tool. This "virtual tutorial" is still somewhat preliminary, but everyone who is interested is invited to have a look at it and make comments. Any input is highly appreciated. It can be found at http://www.rzuser.uni-heidelberg.de/~malbert/ Thanks for your attention! Max ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Thorsten Wilms - 2007-03-24 18:56:51 ```On Sat, Mar 24, 2007 at 06:26:52PM +0100, Maximilian Albert wrote: > > http://www.rzuser.uni-heidelberg.de/~malbert/ I don't get how you change from 2-point to 3-point perspective in the first 2 images. The 2nd image is wrong, anyway, I think. The viewpoint would be above the box, as the top is shown slightly from above. The bottom must be farther away, then. So the VP for the vertical edges would be below, not above the box. I guess in most cases with 2-point perspective, lines for the 3rd direction should be perpendicular to the horizon (has been a while since I learned and used this stuff - with the excpeption of quick hand-drawn approximations :) 1/2/3-point perspective should all be covered, IMHO. 1 point for rooms, 2 for many illustrations, 3 for most realistic illustrations and things like ariel views of skyscrapers. I think the VPs and horizon should be treated as rather secondary, as the user will likely care more about the box. Because if you draw on paper, using construction boxes/lines, at least one VP would be far away from the paper in most cases. The important things are the size and proportions of the box and the inclination of the edges. So I would like being able to move every corner, moving VPs implicitly. Besides move and rotate in relation to the center, there could be rotation around edges. -- Thorsten Wilms Thorwil's Creature Illustrations: http://www.printfection.com/thorwil ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: bulia byak - 2007-03-24 19:06:55 ```On 3/24/07, Thorsten Wilms wrote: > On Sat, Mar 24, 2007 at 06:26:52PM +0100, Maximilian Albert wrote: > > > > http://www.rzuser.uni-heidelberg.de/~malbert/ > > I don't get how you change from 2-point to 3-point perspective > in the first 2 images. The text explains it: "doubleclicking on one of the green PLs, which places the VP at the location where the click occurred" > The 2nd image is wrong, anyway, I think. > The viewpoint would be above the box, as the top is shown slightly > from above. The bottom must be farther away, then. So the VP for > the vertical edges would be below, not above the box. I don't see anything wrong with this one. It's an unconventional perspective but it's built according to the rules. > I guess in most cases with 2-point perspective, lines for the > 3rd direction should be perpendicular to the horizon (has been > a while since I learned and used this stuff - with the excpeption > of quick hand-drawn approximations :) All directions and VPs are freely draggable. You can set them to whatever you want. If you want to rotate everything, preserving the angles between the VPs and directions, just rotate the object by Selector tool. > 1/2/3-point perspective should all be covered, IMHO. And they are. You can freely switch any dimension from infinity VP to visible VP and back. > I think the VPs and horizon should be treated as rather secondary, We don't yet have the notion of horizon at all, at least at this basic stage. Any pair of VPs can be taken to represent a horizon. VPs, on the other hand, are very fundamental for this tool. > as the user will likely care more about the box. Because if you > draw on paper, using construction boxes/lines, at least one VP > would be far away from the paper in most cases. So what? In Inkscape you can always zoom out as far as you need and still drag it freely. > The important > things are the size and proportions of the box Yes, for these we will also have handles to drag. They are just not illustrated yet :) > and the inclination > of the edges. And that is automatically determined from the VPs. > So I would like being able to move every corner, moving VPs > implicitly. When you drag a corner, you change the size/proportion of the box but its perspective (i.e. VPs) remains the same. When you drag the VPs, you change perspective but the box size/proportions remain the same. -- bulia byak Inkscape. Draw Freely. http://www.inkscape.org ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Thorsten Wilms - 2007-03-24 19:49:46 ```On Sat, Mar 24, 2007 at 03:06:55PM -0400, bulia byak wrote: > > The text explains it: "doubleclicking on one of the green PLs, which > places the VP at the location where the click occurred" Oops :) > > The 2nd image is wrong, anyway, I think. > > The viewpoint would be above the box, as the top is shown slightly > > from above. The bottom must be farther away, then. So the VP for > > the vertical edges would be below, not above the box. > > I don't see anything wrong with this one. It's an unconventional > perspective but it's built according to the rules. The perspective is either impossible or it's not a box, so much is obvious for me. Now let's see ... the drawing is below the horizon, you can see the top, that means you look down on it. If you look down, the 3rd vanishing point must be below. Needs a nadir, not a zenith. http://www.khulsey.com/3_point_perspective.html But perhaps allowing such weird stuff makes things easier in the end. > We don't yet have the notion of horizon at all, at least at this basic > stage. Any pair of VPs can be taken to represent a horizon. The horizon is important. Take several boxes with non-parallel side walls as example: their VPs have to be on the same horizon. > > as the user will likely care more about the box. Because if you > > draw on paper, using construction boxes/lines, at least one VP > > would be far away from the paper in most cases. > > So what? In Inkscape you can always zoom out as far as you need and > still drag it freely. My point was not about a technical limitation, but the common practical approach to drawing in perspective: you draw a box and the VPs remain in your imagination only. The angles of the edges step into the fore- ground. > When you drag a corner, you change the size/proportion of the box but > its perspective (i.e. VPs) remains the same. When you drag the VPs, > you change perspective but the box size/proportions remain the same. Hmm. I wonder if you can keep proportions and perspective apart at all, if you have no movable camera and no projection from a reference. First image, if I drag the lower front corner, do I change perspective or proportions? -- Thorsten Wilms Thorwil's Creature Illustrations: http://www.printfection.com/thorwil ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: bulia byak - 2007-03-24 20:40:05 ```On 3/24/07, Thorsten Wilms wrote: > The perspective is either impossible or it's not a box, so much > is obvious for me. Ah, perhaps you mean that the green VP must be on the other side. But, Inkscape is under no obligation to represent only "possible" perspectives :) Just drag the VP down where _you_ want it to be according to your rules :) Others will probably find uses for such "impossible" perspectives. > But perhaps allowing such weird stuff makes things easier in the end. Yes, let's not introduce any limitations unless absolutely necessary. > > We don't yet have the notion of horizon at all, at least at this basic > > stage. Any pair of VPs can be taken to represent a horizon. > > The horizon is important. > Take several boxes with non-parallel side walls as example: > their VPs have to be on the same horizon. Yes, and it's easy to make a regular guideline and to snap all VPs to it. No need to add anything special to the 3D tool for that. > > > as the user will likely care more about the box. Because if you > > > draw on paper, using construction boxes/lines, at least one VP > > > would be far away from the paper in most cases. > > > > So what? In Inkscape you can always zoom out as far as you need and > > still drag it freely. > > My point was not about a technical limitation, but the common practical > approach to drawing in perspective: you draw a box and the VPs remain > in your imagination only. The angles of the edges step into the fore- > ground. That's because on paper, you can't just grab the VP and drag it. So you think in terms of angles. But when you can drag it, it's much easier IMHO :) > > When you drag a corner, you change the size/proportion of the box but > > its perspective (i.e. VPs) remains the same. When you drag the VPs, > > you change perspective but the box size/proportions remain the same. > > Hmm. I wonder if you can keep proportions and perspective apart at all, > if you have no movable camera and no projection from a reference. That's the whole point of this tool. Our proposal is that yes, it's possible. We will try to prove it by coding :) > First image, if I drag the lower front corner, do I change perspective > or proportions? You make the box taller, but all VPs stay unomved. -- bulia byak Inkscape. Draw Freely. http://www.inkscape.org ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Thorsten Wilms - 2007-03-24 21:29:46 ```On Sat, Mar 24, 2007 at 04:40:03PM -0400, bulia byak wrote: > Yes, and it's easy to make a regular guideline and to snap all VPs to > it. No need to add anything special to the 3D tool for that. I think you forget (2d canvas) rotation of the whole thing. -- Thorsten Wilms Thorwil's Creature Illustrations: http://www.printfection.com/thorwil ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: bulia byak - 2007-03-24 21:49:37 ```On 3/24/07, Thorsten Wilms wrote: > On Sat, Mar 24, 2007 at 04:40:03PM -0400, bulia byak wrote: > > > Yes, and it's easy to make a regular guideline and to snap all VPs to > > it. No need to add anything special to the 3D tool for that. > > I think you forget (2d canvas) rotation of the whole thing. Rotating/moving/scaling/skewing a 3D box as a regular object with Selector tool transforms it as a whole, including all its VPs. -- bulia byak Inkscape. Draw Freely. http://www.inkscape.org ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Maximilian Albert - 2007-03-25 16:04:50 ```Hi Thorsten, finally a response from me, too. ;) Since Bulia already replied to pretty much everything you said/asked, I will just make a few general comments, trying to sum it up. I think I can understand your concerns very well, since until rather recently I shared your attitude. My first brainstormed attempt for a proposal used an approach very similar to yours. I asked myself who would use this tool and tried to tailor it to this target audience. The result was something which would probably have been quite usable, but mostly for people who want to draw 2-point perspectives with a horizontal horizon. Users who are interested in more complicated and/or unusual things like the second picture on the website could certainly use it, too, but with a lot more inconvenience since they would have to start with the restricted case. On the other hand, the more general 3D tool can with minimal overhead be made behave like one that was specially designed for 2-point perspectives. Bulia managed to convince me that it is much better to allow for maximal flexibility while preserving maximal simplicity. I think the described tool satisfies this. You can quickly draw any perspective you like. And if you are not perfectly satisfied, you can change it easily. The size of the box can be changed by dragging the corners (which makes them "glide along" the viewpoints, preserving the perspective). On the other hand, the perspective can be changed either by dragging the vanishing points or by dragging the perspective lines themselves. ==> My point was not about a technical limitation, but the common practical approach to drawing in perspective: you draw a box and the VPs remain in your imagination only. The angles of the edges step into the foreground. <== Hmm, after rereading your email I finally understood your objection. And on second thought I agree that it would probably be good to include an option which allows the user to drag PLs separately, without necessarily moving them together (as would be the case when using the method described in the third paragraph). On the other hand, what you have in mind essentially results in a rotation of the dragged PL around a specific corner and within a plane spanned by two of the VPs. I could imagine that in unusual perspectives it's not totally obvious which one that should be and how the user should be able to change it (in most cases, though, it will be the plane containing the VP for the "up" direction, which lies at infinity in the first picture, as well as the one on the PL being dragged). But I will give that some further thoughts, thanks for the suggestion! On third thought ;) your desired behaviour can almost be achieved using the method in the fifth paragraph. Just shift-drag the PL to constrain the movement of the VP to the horizon. This adapts the angle at the corner in a way which should be sufficiently intuitive. It certainly also adapts the angle at another corner, but that could be remedied (if required) by dragging the horizon when that is implemented later on (see below). As far as horizons and similar things are concerned, I agree that they make life much more easier for the average user, and I think we should provide the relevant functionality sooner or later. But in the beginning it is probably best to confine ourselves to the very basics and to make them work/behave properly and intuitively. Later on it's then no problem to add a horizon, make it draggable, restrict the movements of VPs to it, and many more things you could think of. But let's not attack these things before the core tool really works. Cheers, Max ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Thorsten Wilms - 2007-03-25 16:24:21 ```On Sun, Mar 25, 2007 at 06:04:44PM +0200, Maximilian Albert wrote: > finally a response from me, too. ;) Since Bulia already replied to > pretty much everything you said/asked, I will just make a few general > comments, trying to sum it up. Ok, I see my input has been considered and I look forward to the first prototype ;) -- Thorsten Wilms Thorwil's Creature Illustrations: http://www.printfection.com/thorwil ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Thorsten Wilms - 2007-03-25 08:03:38 ```On Sat, Mar 24, 2007 at 05:49:36PM -0400, bulia byak wrote: > On 3/24/07, Thorsten Wilms wrote: > > On Sat, Mar 24, 2007 at 04:40:03PM -0400, bulia byak wrote: > > > > > Yes, and it's easy to make a regular guideline and to snap all VPs to > > > it. No need to add anything special to the 3D tool for that. > > > > I think you forget (2d canvas) rotation of the whole thing. > > Rotating/moving/scaling/skewing a 3D box as a regular object with > Selector tool transforms it as a whole, including all its VPs. Yes. And suddenly the VPs are no longer on the guideline. The horizon doesn't have to be horizontal, so one would need at least angled guidelines anyway. -- Thorsten Wilms Thorwil's Creature Illustrations: http://www.printfection.com/thorwil ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Bryce Harrington - 2007-03-26 07:53:45 ```On Sat, Mar 24, 2007 at 06:26:52PM +0100, Maximilian Albert wrote: > Hi, > > I am planning to submit a proposal for the 3D box tool as a Summer of > Code project. For illustration purposes, I have collected a few ideas > and prepared some graphics regarding possible features. This is meant to > get across how it would "feel" using the new tool. > > This "virtual tutorial" is still somewhat preliminary, but everyone who > is interested is invited to have a look at it and make comments. Any > input is highly appreciated. It can be found at > > http://www.rzuser.uni-heidelberg.de/~malbert/ > > Thanks for your attention! Hi Max, just wanted to say the proposal looks excellent, and seems to cover all the necessary technical points. There's a page in our wiki listing some other questions (like other activities you have planned for the summer, experience with Inkscape, etc.) which would be great to include with your formal application. Bryce ```
 Re: [Inkscape-devel] Illustrations for a planned 3D box tool (SoC) From: Maximilian Albert - 2007-03-26 08:21:50 ```Bryce Harrington schrieb: > Hi Max, just wanted to say the proposal looks excellent, and seems to > cover all the necessary technical points. There's a page in our wiki > listing some other questions (like other activities you have planned for > the summer, experience with Inkscape, etc.) which would be great to > include with your formal application. Many thanks for your feedback! I am currently giving my proposal a final polish. This will also include a further expansion and restructuring of the website, including ideas for future work on features that probably won't be part of the SoC core project (I hope to get it all done till tonight, although the website can and will of course be updated even after the official deadline, in fact during the whole course of the project). I won't forget to include the information you mentioned in my formal application through Google. It will be loosely based on the contents of my initial post to this list (from exactly one week ago, I realize). Thanks, Max ```