Rhino - Moi : Circle on Sphere

 From: PaQ 17 Apr 2011  (1 of 11)
 Ok, first forgive me if the discussion dont seeems appropriate on MoI forum. When I have some time, I like to learn Rhino a little bit more. There are so many functions Oo. I have tried to find some forum, but the main one dont accept any new users. So it's really hard to find a answer. So here's my problem, Making this in MoI take me 2 steps : 1) create a sphere 2) selecting the circle, and draw the circle over the sphere. Simple and easy ... now after one hour of reading the documentation, I still dont get how to do the same process in Rhino. After the sphere creation, I click on the circle/radius tool, then tools/object snap/on object/on polysurface (I dont see this mode in the osnap bar)... then pick the center of the circle, but I cant find a way to align the circle on the polysurface normal :S Turn me crazy ... EDITED: 3 Dec 2015 by PAQ

 From: Michael Gibson 17 Apr 2011  (2 of 11)
 4202.2 In reply to 4202.1 Hi PaQ - well there are a lot of things that are more clunky in Rhino than in MoI, that's just one of many... In several ways MoI is kind of a next generation after Rhino - I mean since I designed Rhino I was quite aware of limitations and irritations in its workflow, and starting MoI from scratch allowed me to make improvements to a lot of the fundamentals and basic operations such as how snapping and drawing works. There isn't any way built in to Rhino's Circle command to make a circle aligned to a surface normal as you can in MoI. You can get it done but you'll have to use some combination of other tools. A few ways that would work would be to set the construction plane first (type CPlane, then type S and push Enter to activate the Surface option, click the sphere surface to select it, then select the point you want to use as the center point of the surface, then right-click to accept default rotation), and then after the cplane is set you can draw a circle and type in 0 and push enter to pick the cplane origin as the circle center point and when you draw it, it will use the cplane orientation. Then you'll want to reset the cplane after that. Another way which might be easier would be to draw a line along the surface normal (type N to activate the Normal option for line - it's a special option because Rhino doesn't have any automatic surface normal straight snap/ortho snap like MoI), then use the AroundCurve option in circle to draw a circle around the base of that line, then delete the line. Another possibility would be to draw the circle elsewhere and then move it on to the surface with OrientOnSrf. But yeah, drawing and snapping is just a lot better in MoI, I worked hard to make the really basic stuff be a lot more fluid and not require so many different kinds of special sub options and special modes and stuff inside of MoI. > (I dont see this mode in the osnap bar) That's because Rhino's osnap bar only has a kind of subset of snaps that are called "running object snaps" - they're ones that are persistent across many point picks. There's a different kind of snap called a "one shot object snap" that you activate just for one point pick, and the onsrf snap is one of those. Also as you may have noticed when you use Rhino's onsrf snap, it's a multi step process where you first pick the surface you want to use and then pick a point on it, you can't just do one click on any surface to activate it. This kind of system with "one shot" and running object snaps is inherited from AutoCAD - a lot of stuff in Rhino is set up to be similar to AutoCAD so that using Rhino feels comfortable from someone who is coming from a background of using AutoCAD a lot. If you do not have that kind of a background much of that stuff will tend to feel more uncomfortable and archaic though. You'll probably run into a lot of frustrations with various stuff like this - you'll probably want to do things more like draw stuff in MoI and copy/paste it over to Rhino when you want to use some Rhino function. I mean when you use Rhino's drawing and snapping system you're basically going back in time to the system that I designed in 1993, and there were many aspects of that which were set up to be similar to AutoCAD's system which was quite a bit older than that... Of course they have made a lot of additions to Rhino since 1993 but all the new stuff is kind of layered on top of the same original design. The reason why MoI works much more smoothly in some of these areas is that it's a more modern design that incorporates stuff like surface normal snapping more directly into its design rather than kind of stratified layers of design with new features layered on top of old... I mean also keep in mind that Rhino was originally designed to run on a 90 Mhz Pentium system, with a wireframe display. That's why some of the stuff is structured the way it is - like for example with the onsrf snap, the reason why it requires 2 picks to do it (first one click to select the particular surface you want to snap on to and then pick the point on it), is because that works better in wireframe mode where you may want to place a point on a surface somewhere where there does not happen to be a wireframe edge or isoparm currently displayed. So that original focus on a wireframe display (in year 1993, remember) has a lot of side effects in the workflow that persist to the current version of Rhino. MoI is designed around a shaded display so stuff like having the whole surface as a displayed thing on the screen under your mouse is part of the workflow design - that difference is really why snapping points on to surfaces while drawing is so much nicer in MoI. EDIT: by the way don't get me wrong - Rhino is definitely very useful and has a lot of functions that are not in MoI, especially stuff like deformation functions. But one of the reasons that they work well in combination with each other is that there is also stuff in MoI that works better, and that includes a lot of the really basic stuff like snapping, drawing, 2D editing with the object frame, exporting well to polygon meshes, ... - Michael EDITED: 17 Apr 2011 by MICHAEL GIBSON

 From: PaQ 17 Apr 2011  (3 of 11)
 4202.3 In reply to 4202.1 Ok I finally find a solution by placing the workplane on surface first ... appreciating MoI more and more :)

 From: Michael Gibson 17 Apr 2011  (4 of 11)
 4202.4 In reply to 4202.1 Hi PaQ, also this part: > I have tried to find some forum, but the main one dont > accept any new users. So it's really hard to > find a answer. The main one is actually very active, but it's not a web forum, it's an old style NNTP (usenet-like) newsgroup. This kind of a group doesn't require you to register or set up a password or anything, so it is open to new users just in how it works. To read it properly you may need to install an NNTP news reader software, like Mozilla Thunderbird. Set the server to news.rhino3d.com, and there will be a list of newsgroups under there, go to the rhino group. Windows used to have a built in newsreader called Outlook Express, but I'm not sure if this is set up by default in Windows 7 or not. If you do have a newsreader set up on your system to handle the news:// protocol, then you can click on this following link to open up the Rhino newsgroup: news://news.rhino3d.com/rhino - Michael

 From: Michael Gibson 17 Apr 2011  (5 of 11)
 4202.5 In reply to 4202.3 Hi PaQ, also looks like we posted a reply on this thread at the same time, so you may miss my long explanation above... - Michael

 From: PaQ 17 Apr 2011  (6 of 11)
 4202.6 In reply to 4202.4 Hi Michael, Thanks for all the info, there are so many tricks like that I have to learn, but I'm really motivated. I was refering to this forum : http://www.rhino3dhelp.com/forum/ but I'll give a try the newsgroup ! By the way I dont find Rhino that archaic you know, I really respect the software. I know snapping system from some modern software much more hard to use (modo ? :)). As I cannot copy/paste between demo version, I really need to learn the basics and get confortable with the navigation etc. Again that's alot for the little free lesson !!! EDITED: 17 Apr 2011 by PAQ

 From: Michael Gibson 17 Apr 2011  (7 of 11)
 4202.7 In reply to 4202.6 Hi PaQ, > I was refering to this forum : > > http://www.rhino3dhelp.com/forum/ No, that's not the main one, you definitely want the official newsgroup from rhino3d.com - that domain above rhino3dhelp.com is different, that's someone else's forum. There is also a web interface for the official newsgroup but it's pretty terrible, you really need to have a newsreader set up to work with it well. You can find the web interface though on the support page at rhino3d.com > By the way I dont find Rhino that archaic you know, I > really respect the software. I know snapping > system from some modern software much more hard to use (modo ? :)) Well, don't get me wrong - Rhino's (and AutoCAD's) snapping is quite effective, particularly in 2D - by archaic I don't particularly mean "ineffective". For snapping in 3D there are some level of being archaic that does impact workflow though, which is the parts that were designed around working on a wireframe display like I was describing previously about "onsrf". I mean basically the reason why you can't just draw a circle on a sphere in Rhino as per your original question is because with a wireframe only display where only a few isoparms of the sphere are being displayed you don't even really think about trying to draw stuff directly in the middle of a surface unlike when you are working with a shaded display. One other part that's generally archaic is the command-line interface that kind of works like a little DOS window at the top of the screen, where you're getting all kinds of options and settings and stuff all spewed out as wads of text. That's can also be fine in the "effective" department, but it's not what people are very used to using (with AutoCAD users as a big exception). - Michael

 From: Michael Gibson 17 Apr 2011  (8 of 11)
 4202.8 In reply to 4202.6 Hi PaQ, > I really need to learn the basics and get confortable > with the navigation etc. You'll probably be ok with navigation pretty quick. Mousewheel for zooming, right-drag in an ortho view for panning, right drag in Perspective view for orbiting. Hold down shift and right-drag in the Perspective view for panning there. Use ZoomTarget to zoom into a particular region (it's like MoI's zoom area tool). To center and fill the view on a selected object, type zsa all with your left hand. Space does the same as Enter, and zsa is an alias for an old command ZoomSelectedExtentsAll. To view everything regardless of selection use zea . - Michael