Why is simple geometry so hard?

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android-originals.com
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Why is simple geometry so hard?

Postby android-originals.com » Thu Oct 11, 2012 11:32 pm

Blender seems to offer the promise of a super-CAD package, able to do everything. Except maybe simple geometry. Take the beginning cube. I have tried and tried to find a way to simply squeeze it up by the bottom face, so that the bottom face sits on the z = 0 plane. Everything, scaling, grabbing, extruding seems to leave vertices in the original position, and lose faces if you delete them. In some case, where I obviously didn't hold my nose right, I've tried to extrude or move the bottom face in the z-direction, only to have it jump off in the x-direction. And then for other unknown reasons, that white ball and color axis designator for the cube "selection" can end up outside of the cube, making it nearly if not impossible center the cube just by typing in coordinates.

Perhaps, for some reason above my pay grade to comprehend, animators need this kind of interface, that an engineer cannot use intuitively. Perhaps, instead of someone writing squirrelly code, god she-he-it is punishing me for being a Blender heretic. For questioning the Holy Interface.

Pardon me, I have to leave now. I feel a burning need to jump on a pile wood and light it.

Tehrasha
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Postby Tehrasha » Fri Oct 12, 2012 1:57 am

The default cube is 2x2x2 in Blender Units (BU) centered on the X,Y and Z axes. So its faces are all plus or minus 1 BU from their respective plane.

After you have selected the entire cube (or the bottom face if you dont care if it remains a cube) in edit mode, moving it to rest on the Z plane is 4 simple key presses.

g -- grab
z -- limit movement to Z-axis only
1 -- move 1 positive blender unit
Enter

If there are artifacts left behind (other faces/vertices/etc..) then there must have been other extruding or copying that has taken place previously, and you are not working with the default cube.
Spacemice Wiki -- Input devices for a 3D world.
Spacemice / Blender Compatibility

android-originals.com
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Postby android-originals.com » Fri Oct 12, 2012 9:45 pm

"g -- grab
z -- limit movement to Z-axis only
1 -- move 1 positive blender unit
Enter"

Thanks. Amazing. It works. I could have sworn I tried that. Maybe I don't have to make like a South Vietnam Buddhist monk and can get off with just wet noodle self-flagellation.

But if you want to see something interesting and somewhat counter-intuitive, try selecting the bottom vertices, type in E followed by 1, and before hitting enter, hit cntl-z a half dozen times.

Very confusing to some of us who are easily confused, leading one to think that one is perhaps sanity-challenged. Well, maybe after the cursing stops. I'm still going to go back to PhotoShop 7 for a while. It tends to conform to my flat Earth ideology.

It would be nice if I could save PhotoShop paths, import them into Blender (*.ai format), and extrude, etc., but I see that's no longer an option. I have had trouble with some tests in 2.49, getting unexpected scales and offsets from the origin. You can do a lot of things with paths in PhotoShop, including getting 3D effects.
See http://android-originals.com/drawings/index.html
Particularly the bottom four links in the left frame, which have color renditions. Not as stunning as Blender, perhaps, but some of us old flat-worlders have learned to make do. Hmm, wouldn't it be something if you could take a PhotoShop file with layers and layer effects and translate them all into a 3D Blender file with all the appropriate lighting and textures. And no, I don't have the capability to do that.

Tehrasha
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Joined: Wed Apr 21, 2010 6:21 am
Location: Iowa

Postby Tehrasha » Fri Oct 12, 2012 11:42 pm

android-originals.com wrote:But if you want to see something interesting and somewhat counter-intuitive, try selecting the bottom vertices, type in E followed by 1, and before hitting enter, hit cntl-z a half dozen times.


Well at that point, you have not completed the extrude, so there is nothing to 'undo' yet. In fact, at that point, it doesnt matter if you use the ctrl key at all. Just repeatedly pressing Z gives the same effect, the extrude aternating between the Z-axis, the X-axis, or negatively along the Z axis.
At that point pressing X, Y or Z allows you to manipulate which axis the extrude occurs, though not in a very intuitive way. I can understand having the option to reverse the direction of the extrude, but that does not always happen.... neat, you might have found a bug. :)

What catches a lot of people is when they extrude a face, then decide against it and simply right-click to cancel out of it. They do not realize that the extrude still happened and that the new vertices are still there, they just never moved.

So the next time they try to select those vertices, they get some of the old ones, and some of the new ones and all kinds of silly and confusing happens.
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stiv
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Postby stiv » Sat Oct 13, 2012 6:02 am

Blender seems to offer the promise of a super-CAD package,


It may seem so, but Blender is not a CAD package. Never was, and likely never will be. At least not until it gets some new data structures.

android-originals.com
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Postby android-originals.com » Wed Oct 17, 2012 9:30 pm

stiv wrote:
Blender seems to offer the promise of a super-CAD package,


It may seem so, but Blender is not a CAD package. Never was, and likely never will be. At least not until it gets some new data structures.


Ah, but it's almost there. See http://www.rab3d.com/tut_blender.php

After all, I've been doing CAD in PhotoShop 7, making good use of shapes, guides, paths and the measure tool. I've made and used wood router templates that way. Printed them out on business card stock, then spliced and pasted them together on Masonite. I might have done that in Blender and had 3-D renderings and CNC files to boot, if I had known the interface as well and found it as easy to use.

But compared to PhotoShop, keeping track of all the tools and variations in Blender is a bit like keeping track of all the characters in War and Peace. Or maybe The Game of Thrones, from what I read about it. Sometimes less is more. As I indicated in another post, some well thought out switches to simplify Blender's capabilities for certain user groups, especially us easily-confused newbies, could be useful.


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