Testers wanted: perspective mode (early stages)

[gwojcik]

Sorry for not replying before, I don’t have much time in last week.

Also I’m only beginner in drawing and I know perspective more in theory than practice. Because of that, your suggestions are important.

@bleke

I’m not sure how the angle values works… they look like coordinates, but the scale is very small near the Center point and very large when the numbers approach 90.

This is top view of drawing scene, V is viewer, P is image plane, C, R and L are default points.
For each vanishing point are computed angle between forward (C) direction and vanishing point.
Thad angle is not linearly related to image coordinates, for example difference between 10 and 20 degrees VPs is much smaller than between 60 and 70 degrees.
This is also main reason for having default “special” points. This function will be much more visible after implementation of point grouping.

@bleke

I finally figured out how adding VP’s works… you have to click “add” then click on the canvas to place it. Having it appear near the Center point would probably be more discoverable. At least make it appear in the list when you click Add, because as it is now it seems that nothing happens when you click Add.

I don’t want adding points automatically. User should be in control where to place new point.
Maybe making button to toggle button and allowing placing multiple VPs while it is pushed?

@bleke

It feels as if the VP setup you use should be specific to the image you are working on, so clicking “New Canvas” should reset the VP mode. Now the old VP’s remain even though you have a new image.

Added to todo list.

@bleke

I guess those three points that you get when you activate perspective mode are a sort of invisible horizon line? In that case I would prefer if it was visible, like the axis I made in the images above. I don’t really see why there has to be three points for that, One default point and one handle point should be enough. The default and handle points don’t have to be vanishing point (and should have another appearance so that no-one confuses them for a vanishing points). Then you could place points of your own that won’t spin around like a simulated planetary system.

Yes, one of their roles is defining horizontal line.
In one next update could be hidden by default. There could be type of points that is not affected by these special pints.

@bleke

What do you think of my ideas above? Can they be merged with what you are doing? For example I think that the pivot point (see the third picture) and your “default” point can be one and the same. I guess that would make the horizon line obligatory, but that should be ok. Especially if it can be hidden using the eye symbol.

As said @tilkau your idea of measurement axis could be used not only in connection with perspective mode.
This could be implemented as special case of grouping. Two pints could be chosen to define additional horizon line or measurement axis.