Setting exact angle between paths in Inkscape
So I want to draw a line of pseudo-3D boxes with a changing amount of "segments" of constant width (e.g. a box of 3 segments of 60p width, 180p in all, and one of 6 segments of 60p width, 360p in all). The depth of the boxes should be the same, so they align nicely.
Failed example (I want the z-angles of the boxes to be parallel, so I can string up any amount of these boxes in a row without it looking odd):
So far, I can only manage something like this, and my attempts to correct the viewing angle distort more than help.
To be honest, I've colored the first 3D-box and copied the others from it to save me the hassle of deleting unused areas and re-coloring each time, so perhaps the answer is "Use independent boxes and adjust the vanishing points manually", but if there's a way to set the angle between to adjacent segments of a path, it would be a lot more comfortable. Does this exist? Alternatively, am I missing an obvious other way to achieve what I want?
The z angle of the boxes won't be parallel because the back face is not the same size as the front face. What you are essentially making is a perspective drawing, and parallel lines in perspective don't stay parallel. You can move the endpoints with the edit paths tool. Select all paths using the shift key then click and drag to select the nodes you want. With those nodes selected, click and drag one to move them.
You can also go the menu object>transform. Under the rotate tab you can type in values to rotate. If you want to rotate from an endpoint turn on snap to cusp node, then select the path, click the path again to change the transforms to rotate and shear, then move the center of rotation to an end point.