Part View Direction in Drawing Workbench

[NormandC]

Hey guys,

I'm trying to figure out how the Shape View direction works in the Drawing workbench. We have 3 values for x, y, z, and we can enter any value. For an isometric view, values are 1,1,1 and rotation is 60º. Why the rotation by the way? And why can we use values greater (or lower) than 1? What do these values stand for?

I've managed to figure out the values for a dimetric view (1,1,0.4 & zero rotation), but for the life of me I can't find values for a trimetric view which would look like the one in this picture:

http://en.wikipedia.org/wiki/File:Graph ... arison.png

Another thing that confuses me is that for a top or front view, the insertion point on the page is placed as the lower left corner of the view (or bounding box), but for a right view, it's the right lower corner.

While I'm at it... is there a way to create a view of multiple objects, like an assembly of parts? The create view button only works with fused objects, and the tool in the 2D Drafting workbench doesn't work on 3D solids.

Thanks!

[yorik]

The vector (x,y,z) is the projection direction: for a top view, you project "downwards" (0,0,-1), for a front view you project on the XZ plane (0,1,0), left view on the YZ plane (1,0,0) etc...
I suppose the maximum value of 1 is because that vector has to stay normalized (= its length is always 1) so no direction can possibly be greater than 1...
I think for making "canonical" projections like the example you linked, you must indeed play with a combination of projection direction and orientation. I think you must experiment and see what values are good...

But this is very useful, if you happen to find good combinations, we could maybe make some presets with them?

[NormandC]

The vector (x,y,z) is the projection direction: for a top view, you project "downwards" (0,0,-1), for a front view you project on the XZ plane (0,1,0), left view on the YZ plane (1,0,0) etc...

Actually, for top view it is 0,0,1, so it seems the vector is already reversed.

I suppose the maximum value of 1 is because that vector has to stay normalized (= its length is always 1) so no direction can possibly be greater than 1...

But then as I said, why am I able to enter any value, and that includes values greater than 1? (try it you'll see) That is why these values confuse me. Or maybe they're coordinates for a start point of a vector ending at the center of the object? And why sometimes the view rotates, like the ISO that you need to rotate 60º to put it right? I guess I'd need to familiarize myself with Coin3D to find out. Which considering my level of understanding, I'm probably better off experimenting blindly till I stumble on the right numbers by accident.

But this is very useful, if you happen to find good combinations, we could maybe make some presets with them?

When I model in Solid Edge I like to toggle between iso, dimetric and trimetric views, I have keyboard shortcuts mapped. I'd like to get the same in FreeCAD's Gui, but it is a very minor and unimportant wish. For drawing views I find that either dimetric or trimetric are often clearer than iso.

I found the Automatic Drawing script in the Macros Recipes page and I'm trying to modify it to my needs. For one thing I'm used to third-angle projection, first-angle projection confuses the hell out of me! Those silly north americans! Changing the ortho views direction and rotation was easy but now the views are not aligned anymore. Ah well, another thing to figure out.

If I ever manage to develop the knowledge and skill, this is what I'd like to do: a drawing view wizard. First you choose your base view (top, front, right), then you're given a dialog box where you tick the projected views that you want (this capture is taken from Solid Edge):

[NormandC]

Or maybe they're coordinates for a start point of a vector ending at the center of the object? And why sometimes the view rotates, like the ISO that you need to rotate 60º to put it right?

Nope, just drew a line from 0,0,0 to 1,1,1 (direction for iso), that's not it.

[NormandC]

Ok, with some trial and error I managed to get some decent combinations. I didn't like the projection angles in the graphic I linked from Wikipedia, so I based my trimetric and dimetric views on the ones in Solid Edge, or should I say as close as I could get.

Dimetric View
Drawing view rotation: 277.93
Shape View direction: 0.4, 1, 0.4

Trimetric View
Drawing view rotation: 180
Shape View direction: 0.43, 0.32, 0.25

How did I get the exact rotation on the dimetric you'll ask? Well I exported my drawing page to DXF, opened it in LibreCAD so I could measure and adjust the angle.

I found out that the ratio between the xyz values is what counts. (2,2,2) or (0.5,0.5,0.5) will both give an iso view.

BTW you know about LibreCAD? It's a QCad fork (formerly CADuntu) ported to Qt4 (with the added bonus that it supports polylines, as the QCad Community Edition has those disabled). In Ubuntu, it's much more easier on the eye than that old QCad CE 2.0.5.0.

Man just realized I spent my whole evening on that!!!

[yorik]

Ah, great! That will be pretty useful...

I think mounting a dialog to choose between standard projections can be easy... The thing is, I'm not sure where it could fit in.
What about adding a button to the Drawing toolbar, something named "standard projections", that you would use like this:

- select objects in the 3D view, press the standard "create view" button
- select the created FeatureViews, press the new "standard projections" button
- choose your projection, the views get updated.

Or that dialog could be added to the standard "create view" command...
We could try to draw an .ui dialog and see where it could go.

[NormandC]

That would be nice.

Instead of a dialog window, maybe it could be sent to the Tasks tab...

[yorik]

Good idea!

[xf3qc]

at last the vector is pointed!
Thank you for the direction sir.

Dimetric View
Drawing view rotation: 277.93
Shape View direction: 0.4, 1, 0.4

Trimetric View
Drawing view rotation: 180
Shape View direction: 0.43, 0.32, 0.25