A script to place cursor on objects' surface (and some other functionality)

dairin0d · November 18, 2011, 1:43pm

Cool Thanks! Could you please point me to the corresponding part of API documentation?

Edit: Hmm, seems like there is no API documentation on that. A hidden feature?

bluecd · November 18, 2011, 2:25pm

Thats a very interesting feature undergoing on here
Did you consider enhancing 3dCursor functionality by eg: full snap modes, origin definition, magnet ??

dairin0d · November 18, 2011, 2:30pm

The addon already supports snapping (see the wiki).
As for origin definition and magnet… please explain in more detail %)

Meta-Androcto · November 18, 2011, 2:48pm


       # turn off undo
        undo = bpy.context.user_preferences.edit.use_global_undo
        bpy.context.user_preferences.edit.use_global_undo = False

        # restore pre operator undo state
        bpy.context.user_preferences.edit.use_global_undo = undo

dairin0d · November 18, 2011, 9:07pm

Ah, you meant global undo That wouldn’t solve the problem, though… Even with Global Undo turned off, editmode switching is still recorded in Mesh Undo history (and as that, erases the history beyond this point). Even more, turning Global Undo on/off is recorded in blend’s undo history too…

Having an option to actually freeze undo history for the duration of some operations would be nice ^^

For example:

with bpy.utils.freeze_undo_history():
    # ... do some sneaky operations
# At this point, undo history is the same it was before freeze_undo_history().
# Even more, the __exit__ method could actually revert any changes
# (that may be undesirable, however).

bluecd · November 20, 2011, 1:33pm

Have to explain honestly -I meant CAD style object snap (…ooooppzz for the word CAD here…):
Snap (both in object in edit mode respectively) to

2D(regular): endpoint, midpoint(or s.c. divisor- every 'n’th segment of a given distance), tangent, node(Edit), center intersection
, extension, perpendicular…
3D: Vertex, Midpoint on edge, center of face, perpendicular

Origin definition: w/above manipulation so one could move and operate origin (local/world 0,0,0) easily, define it by 3 points(x,y,z on an object eg.) by object, by view, save&restore an ucs(User Coordinate System).

Magnet: i meant defineable ‘gravitation’ to such abovementioned point within eg. range of circle Blender’s cursor - so one could easily snap to a point w/no miss.
So is this-in short…-)

dairin0d · November 21, 2011, 2:39pm

Hmm, CAD spannings and magnet… Seminumerical’s cursor addon (Cursor Control) deals with some of them, and our addons seem to be generally compatible. To be honest, I’d like to see CAD tools in Blender too, but I have too little experience in this area to try to tackle such broad topic.

As for user coordinate systems, I have an idea how to implement this hacky-way (using e.g. empties to store different systems; when user switches to such UCS, origin will be set to “cursor”, cursor will be sticked to the empty, and a custom transform orientation will be aligned with the empty). Maybe I’d even add that before 2012

bluecd · November 24, 2011, 1:28am

some examples that illustrate my ideas:
(first one-see command line for UCS manipulation options, second-preset snaps, third-on-the-fly(modal) snaps)

chafouin · November 28, 2011, 4:23am

Hi. I’m using this add on since I find it really nice. Unfortunately it works without any problem when I activate it in the preferences, but when I close Blender and reopen it, I keep getting Traceback errors:

Traceback (most recent call last):
File “D:\Blender\Blender 2.60\2.60\scripts\addons\space_view3d_enhanced_3d_cursor.py”, line 4881, in modal
km = wm.keyconfigs.active.keymaps[‘Window’]
KeyError: ‘bpy_prop_collection[key]: key “Window” not found’

location:<unknown location>:-1

Any idea about what’s causing it?

dairin0d · November 28, 2011, 9:57am

Hmm… What version/build of Blender are you using? Currently the addon uses an ugly hack to properly register keymaps on startup, but it works fine for the builds I have… I’ll try to see if there is a better way to do it after 2.61 is out.

bluecd · November 28, 2011, 11:41am

no object mode…??

dairin0d · November 28, 2011, 11:48am

Err… bluecd, what do you mean by “no object mode…?” Was that supposed to be a bug report? :eyebrowlift2:

bluecd · November 28, 2011, 11:54am

Wooouubbzzzz…, i took another Enhanced Cursor switched on. Your addon…I CANT ACTIVATE IN ADDON menu !!!

dairin0d · November 28, 2011, 12:12pm

Hmm, I’ve downloaded latest build from graphicall, seems to work just fine… Again, what version/build are you using?

bluecd · November 28, 2011, 12:17pm

already OK.sorry -i am just trying to get the idea how it works…(with ALT selects whole row)

chafouin · November 28, 2011, 12:32pm

I use this build: http://graphicall.org/444
I tried on a previous one as well (2 days ago I think) and I had exactly the same error. I’m using maya presets and that’s pretty much it, nothing else fancy.

dairin0d · November 28, 2011, 1:06pm

Aha! The problem was with Maya keymap presets. Thanks for the report I fixed the issue, latest version of addon should work properly.

chafouin · November 29, 2011, 1:55am

Thanks for the very quick fix, I’m really enjoying this cursor Actually moving vertices / edges / faces should be as easy as this!

bluecd · November 29, 2011, 4:04am

I have to admit you made a huge work - thank you a lot !!
Yet let me some constructive critique: the functionality of the script ,although extent seems a bit complicated…
How eg. could i grab a cube snapping it firstly w/holding MB(i got reversed L&R) and then…again trying to snap to a target-here (still dragging the object by snapped point) you cant activate 3d snap tripod again…,got to be like that?

Does not seem to snap to curves ??
I would suggest to add some option toggle switch:

either you move Blenders circular red-white cursor alone OR
you move the cursor AND the Blenders X,Y,Z tripod [Origin]. What do we need additional tripod for?
What makes the axes alignment ? (for a cube they dont align the ortho edges…?)

Midpoints of an Edge/Center of a Face possible to snap also ?

Excuse my messing in Your results but I felt so comfortable You made sucha smart approach to the Problem of Snapping that i would like to suggest max. functionality features You can probably achieve…)

dairin0d · November 29, 2011, 8:43am

Err… bluecd, I don’t really understand what you’re trying to say %) I guess by “tripod” you mean 3D manipulator…? Maybe you can provide an explanation with screenshots of what you want to achieve?

My cursor script currently snaps only to surfaces/polygons, or to edges/vertices that belong to surfaces. Recently I came up with an idea that may allow to snap to stand-alone edges and vertices too, but this is perhaps a long-term task.
You can set pivot to Cursor – this will make 3D manipulator move with cursor. As for “additional tripod” and “What makes the axes alignment”, I failed to understand your idea %)
To snap cursor to midpoints, hold Shift while in appropriate snapping mode (this should be explained in the wiki).

As for suggestions, I have little free time right now, but I’ll try to take them into account when I start working on CAD-like functionality.