imeBinder.CSharpArgumentInfo.Create'
Is it possible to solve this issue?
using System;
using IronPython.Hosting;
using IronPython.Runtime;
using Microsoft.Scripting;
using Microsoft.Scripting.Hosting;
using Microsoft.CSharp;
namespace Bob.Meshes {
public class pythonFromCShapr {
ScriptEngine engine = Python.CreateEngine();
public pythonFromCShapr() {
}
public void something() {
dynamic scope = engine.CreateScope();
scope.Add = new Func<int, int, int>((x, y) => x + y);
Console.WriteLine( scope.Add(2, 3));
}
}
}…
e a fundamental failure on my part. On the other hand, Grasshopper isn't supposed to be on a par with most other 3D programs. It is emphatically not meant for manual/direct modelling. If you would normally tackle a problem by drawing geometry by hand, Grasshopper is not (and should never be advertised as) a good alternative.
I get that. That’s why that 3D shape I’m trying to apply the voronoi to was done in NX. I do wonder where the GUI metaphor GH uses comes from. It reminds me of LabVIEW.
"What in other programs is a dialog box, is 8 or 10 components strung together in grasshopper. The wisdom for this I often hear among the grasshopper community is that this allows for parametric design."
Grasshopper ships with about 1000 components (rounded to the nearest power of ten). I'm adding more all the time, either because new functionality has been exposed in the Rhino SDK or because a certain component makes a lot of sense to a lot of people. Adding pre-canned components that do the same as '8 or 10 components strung together' for the heck of it will balloon the total number of components everyone has to deal with. If you find yourself using the same 8 to 10 components together all the time, then please mention it on this forum. A lot of the currently existing components have been added because someone asked for it.
It’s not the primary components that catalyzed this thought but rather the secondary components. I was toying with a component today (twist from jackalope) that made use of three toggle components. The things they controlled are checkboxes in other apps.
Take a look at this jpg. Ignore differences; I did 'em quickly. GH required 19 components to do what SW did with 4 commands. Note the difference in screen real estate.
As an aside, I really hate SolidWorks (SW). But going forward, I’ll use it as an example because it’s what most people are familiar with.
"[...] has a far cleaner and more intuitive interface. So does SolidWorks, Inventor, CATIA, NX, and a bunch of others."
Again, GH was not designed to be an alternative to these sort of modellers. I don't like referring to GH as 'parameteric' as that term has been co-opted by relational modellers. I prefer to use 'algorithmic' instead. The idea behind parameteric seems to be that one models by hand, but every click exists within a context, and when the context changes the software figures out where to move the click to. The idea behind algorithmic is that you don't model by hand.
I agree, and disagree. I believe parametric applies equally to GH AND SW, NX, and so forth, while algorithmic is unique to GH (and GC and Dynamo I think). Thus I understand why you prefer the term. I too tend to not like referring to GH as a parametric modeler for the same reason.
But I think it oversimplifies it to say parametric modelers move the clicks. SW tracks clicks the same way GH does; GH holds that information in geometry components while SW holds it in a feature in the feature tree. In both GH and SW edits to the base geometry will drive a recalculation, but more commonly, it’s an edit to input data, beit equations or just plain numbers, that drive a recalculation.
I understand the difference in these programs. What brought me to GH is that it can create a visual dialog that standard modelers can’t. But as I've grown more comfortable with it I’ve come to realize that the GUI of GH and the GUI of other parametric modelers, while looking completely different, are surprisingly interchangeable. Do not misconstrue that I’m suggesting that GH should replace it’s GUI with SW’s. I’m not. I refrain from suggesting anything specific. I only suggest that you allow yourself to think radically.
This is not to say there is no value in the parametric approach. Obviously it is a winning strategy and many people love to use it. We have considered adding some features to GH that would make manual modelling less of a chore and we would still very much like to do so. However this is such a large chunk of work that we have to be very careful about investing the time. Before I start down this road I want to make sure that the choice I'm making is not 'lame-ass algorithmic modeller with some lame-ass parametrics tacked on' vs. 'kick-ass algorithmic modeller with no parametrics tacked on'.
Given a choice, I'd pick kick-ass algorithmic modeller with no parametrics tacked on.
2. Visual Programming.
I'm not exactly sure I understand your grievance here, but I suspect I agree. The visual part is front and centre at the moment and it should remain there. However we need to improve upon it and at the same time give programmers more tools to achieve what they want.
I'll admit, this is a bit tough to explain. As I've re-read my own comment, I think it was partly a precursor to the context sensitivity point and touched upon other stated points.
This now touches upon my own ignorance about GH’s target market. Are you moving toward a highly specialized tool for programmers and/or mathematicians, or is the intent to create a tool that most designers can master? If it’s the former, rock on. You’re doing great. If it’s the latter, I’m one of the more technically sophisticated designers I know and I’m lost most of the time when using GH.
GH allows the same freedom as a command line editor. You can do whatever you like, and it’ll work or not. And you won’t know why it works or doesn't until you start becoming a bit of an expert and can actually decipher the gibberish in a panel component. I often feel GH has the ease of use of DOS with a badass video card in front.
Please indulge my bit of storytelling. Early 3D modelers, CATIA, Unigraphics, and Pro-Engineer, were unbelievably difficult to use. Yet no one ever complained. The pain of entry was immense. But once you made it past the pain threshold, the salary you could command was very well worth it. And the fewer the people who knew how to use it, the more money you could demand. So in a sense, their lack of usability was a desirable feature among those who’d figured it out.
Then SolidWorks came along. It could only do a fraction of what the others did, but it was a fraction of the cost, it did most of what you needed, and anyone could figure it out. There was even a manual on how to use it. (Craziness!) Within a few short years, the big three all had to change their names (V5, NX, and Wildfire (now Creo)) and change the way they do things. All are now significantly easier to use.
I can tell that the amount of development time that’s gone into GH is immense and I believe the functionality is genius. I also believe it’s ease of use could be greatly improved.
Having re-read my original comments, I think it sounded a bit snotty. For that I apologize.
3. Context sensitivity.
"There is no reason a program in 2014 should allow me to make decisions that will not work. For example, if a component input is in all cases incompatible with another component's output, I shouldn't be able to connect them."
Unfortunately it's not as simple as that. Whether or not a conversion between two data types makes sense is often dependent on the actual values. If you plug a list of curves into a Line component, none of them may be convertible. Should I therefore not allow this connection to be made? What if there is a single curve that could be converted to a line? What if you want to make the connection now, but only later plan to add some convertible curves to the data? What you made the connection back when it was valid, but now it's no longer valid, wouldn't it be weird if there was a connection you couldn't make again?
I've started work on GH2 and one of the first things I'm writing now is the new data-conversion logic. The goal [...] is to not just try and convert type A into type B, but include information about what sort of conversion was needed (straightforward, exotic, far-fetched. etc.) and information regarding why that type was assigned.
You are right that under some conditions, we can be sure that a conversion will always fail. For example connecting a Boolean output with a Curve input. But even there my preferred solution is to tell people why that doesn't make sense rather than not allowing it in the first place.
You bring up both interesting points and limits to my understanding of coding. I’ve reached the point in my learning of GH where I’m just getting into figuring out the sets tab (and so far I’m not doing too well). I often find myself wondering “Is all of this manual conditioning of the data really necessary? Doesn’t most software perform this kind of stuff invisibly?” I’d love to be right and see it go away, but I could easily be wrong. I’ve been wrong before.
5. Components.
"Give components a little “+” or a drawer on the bottom or something that by clicking, opens the component into something akin to a dialog box. This should give access to all of the variables in the component. I shouldn't have to r-click on each thing on a component to do all of the settings."
I was thinking of just zooming in on a component would eventually provide easier ways to access settings and data.
I kinda like this. It’s a continuation of what you’re currently doing with things like the panel component.
"Could some of these items disappear if they are contextually inappropriate or gray out if they're unlikely?"
It's almost impossible for me to know whether these things are 'unlikely' in any given situation. There are probably some cases where a suggestion along the lines of "Hey, this component is about to run 40,524 times. It seems like it would make sense to Graft the 'P' input." would be useful.
6. Integration.
"Why isn't it just live geometry?"
This is an unfortunate side-effect of the way the Rhino SDK was designed. Pumping all my geometry through the Rhino document would severely impact performance and memory usage. It also complicates the matter to an almost impossible degree as any command and plugin running in Rhino now has access to 'my' geometry.
"Maybe add more Rhino functionality to GH. GH has no 3D offset."
That's the plan moving forward. A lot of algorithms in Rhino (Make2D, FilletEdge, Shelling, BlendSrf, the list goes on) are not available as part of the public SDK. The Rhino development team is going to try and rectify this for Rhino6 and beyond. As soon as these functions become available I'll start adding them to GH (provided they make sense of course).
On the whole I agree that integration needs a lot of work, and it's work that has to happen on both sides of the isle.
You work for McNeel yet you seem to speak of them as a separate entity. Is this to say that there are technical reasons GH can only access things through the Rhino SDK? I’d think you would have complete access to all Rhino API’s. I hope it’s not a fiefdom issue, but it happens.
7. Documentation.
Absolutely. Development for GH1 has slowed because I'm now working on GH2. We decided that GH1 is 'feature complete', basically to avoid feature creep. GH2 is a ground-up rewrite so it will take a long time until something is ready for testing. During this time, minor additions and of course bug fixes will be available for GH1, but on a much lower frequency.
Documentation is woefully inadequate at present. The primer is being updated (and the new version looks great), but for GH2 we're planning a completely new help system. People have been hired to provide the content. With a bit of luck and a lot of work this will be one of the main selling points of GH2.
It begs the question that I have to ask. When is GH1.0 scheduled to launch? And if you need another person to proofread the current draft of new primer.
patrick@girgen.com
I can’t believe wikipedia has an entry for feature creep. And I can’t believe you included it. It made me giggle. Thanks.
8. 2D-ness.
"I know you'll disagree completely, but I'm sticking to this. How else could an omission like offsetsurf happen?"
I don't fully disagree. A lot of geometry is either flat or happens inside surfaces. The reason there's no shelling (I'm assuming that's what you meant, there are two Offset Surface components in GH) is because (a) it's a very new feature in Rhino and doesn't work too well yet and (b) as a result of that isn't available to plugins.
I believe it’s been helpful for me to have figured this out. I recently completed a GH course at a local Community College and have done a bunch of online tutorials. The first real project I decided to tackle has turned out to be one of the more difficult things to try. It’s the source of the questions I posted. (Thanks for pointing out that they were posted in the wrong spot. I re-posted to the discussions board.)
I just can't seem to figure out how to turn the voronoi into legitimate geometry. I've seen this exact question posted a few times, but it’s never been successfully answered. What I'm showing here is far more angular than I’m hoping for. The mesh is too fine for weaverbird to have much of an effect. And I haven't cracked re-meshing. Btw, in product design, meshes are to be avoided like the plague. Embracing them remains difficult.
As for offsetsurf, in Rhino, if you do an offsetsurf to a solid body, it executes it on all sides creating another neatly trimmed body thats either larger or smaller than the original. This is how every other app I know of works. GH’s offsetsurf creates a bunch of unjoined faces spaced away from the original brep. A common technique for 3D voronois (Yes, I hit the voronoi overuse easter egg) is to find the center of each cell and scale them by this center. If you think about it, this creates a different distance from the face of the scaled cell to the face of the original cell for every face. As I've mentioned, this project is giving me serious headaches.
Don't get me wrong, I appreciate the feedback, I really do, but I want to be honest and open about my own plans and where they might conflict with your wishes. Grasshopper is being used far beyond the boundaries of what we expected and it's clear that there are major shortcomings that must be addressed before too long. We didn't get it right with the first version, I don't expect we'll get it completely right with the second version but if we can improve upon the -say- five biggest drawbacks (performance, documentation, organisation, plugin management and no mac version) I'll be a happy puppy.
--
David Rutten
Thank you for taking the time to reply David. Often we feel that posting such things is send it into the empty ether. I’m very glad that this was not the case.
And thank you for all of the work you've put into GH. If you found any of my input overly harsh or ill-mannered, I apologise. It was not my intent. I'm generally not the ranting sort. If I hadn't intended to provide possibly useful input, I wouldn't have written.
Cheers
Patrick Girgen
Ps. Any pointers on how to get a bit further on the above project would be greatly appreciated.
…
le and grasshopper timer to simplify simulation control. Double click the main Kangaroo component to open this remote. There are buttons for Stop(reset), Play, Pause, and Step (moves the simulation forward one iteration).
Line-line force - allows interaction between line segments - they are treated as rigid cylinders. As with springs, there are settings for offset and rest distance, so this can be used to simulate colliding rods, and also for keeping cylinders tangent to one another (can be used for reciprocal structures).
Gear simulator - collision between curves in a plane, can be used for various mechanical simulations - cams, gears, rack and pinions etc.
Developablize force - adjusts vertices of a mesh locally, to make angles around each interior vertex sum to 2*Pi, so the mesh can be unfolded to a flat sheet without stretching.
Volume dependent pressure force - allows you to set a rest volume for a mesh instead of just a fixed pressure. When combined with Laplacian smoothing for area minimization, this can be used to optimize for CMC (constant-mean-curvature) surfaces. It will also work on open meshes.
Translation lock - maintains a fixed relationship between a pair of points. This can be used to enforce periodic boundary conditions for TPMS.
Equalize angles force - given a set of angles (defined by 3 points each), this tries to adjust them all to become equal.
Mirror symmetry force - can be used to minimize curvature variation, and optimize for higher order curve continuity. It can also be used for simulating torsional resistance in curved rods.
True minimal surface relaxation - Laplacian smoothing force now includes an option for cotangent weighting, which optimizes for zero mean curvature, unlike spring based methods, or uniform weighted Laplacian smoothing which only roughly approximate this.
Fast sphere collide - allows much faster collision detection between large numbers of spheres. By placing these spheres at the vertices, this can also be used for collision between meshes.
Force-density element - an experimental one, more on this later
Projected-force - adjusts its strength so the component of the force in a given direction stays constant.
New mesh tools:
WarpWeft - sorts the edges of a quad mesh into warp and weft directions. This can be used to assign them different stiffness in fabric form-finding.
Checkerboard - sort the faces of a mesh into 2 lists so that 2 faces of the same colour are never adjacent.
MeshDirection - sorts the vertices of a quad mesh to give it a sort of u-v directionality
Refine Strips - subdivision in one direction only - can be used to generate developable strips
Stripper - separates out the strips of quads from a larger mesh
Unroller - unfolds a quad strip to flat without stretching
MeshMap - maps points from one mesh to another (can be used together with circle-packing to generate conformal mappings)
Reciprocal structure - generates starting geometry for a reciprocal structure from any input mesh (using the Plankton mesh library *Note* If you already have the Plankton components installed, you will need to update to version 0.3.0, which is available from here)
ReMesher - adjusts the connectivity of a mesh by flipping, splitting and collapsing edges to make all edge lengths closer to a target value
Diagonalize - creates a new face for every edge of the original mesh. Can be used on quad meshes to easily convert to a diagrid.
Refine - simple non-smoothing subdivision, splitting quads into 4 quads, and triangles into 4 triangles
QuadDivide - subdivide quads by any number squared, not just powers of 4
Corners - finds the corner vertices of a quad mesh
ByParent - simple quad subdivision, keeping the output grouped by parent face.
User objects:
The download comes with an increased collection of user objects to simplify setting up common simulation types - Including a simple to use origami simulator, a reciprocal structure generator, and a tool to generate compact circle packings from a CP mesh.
General:
Geometry input now accepts polylines and straight curves.
Hinges can now be fold completely flat in both directions.
Various other minor bug fixes and speed improvements (including much faster removeDuplicatePoints/Lines components)
*****
I've not yet updated all the documentation and example files to reflect this new version, but over time I will keep posting here with new demos and explanation of all these new features. I'll try and add a few new examples each week. Vote in the comments below if there is a feature mentioned above that you're particularly keen to hear more about soon.
No doubt there are still some bugs to be discovered. If something isn't working the way you expect or want it to, please post in this forum (ideally with a description or sketch of what you think should be happening, and a clear description of what happens instead and any error messages).
There are also some more new features that weren't quite ready to make it into this release, but are on the way shortly...
Kangaroo remains completely free, for personal, academic, and commercial use. I'm always interested to hear about projects done using it, and suggestions for improvements or additions.
Daniel
…
ger work.
Be aware, this release breaks file-forwards compatibility. You will not be able to open gh and ghx files saved with 0.8.0050 on previous versions, though of course you should be able to open old files without problems. If this is not the case, please yell loudly.
If you're having trouble loading Grasshopper, note that you must have the latest Microsoft C++ Runtimes installed on your machine. They can be downloaded from the microsoft website.
The new release can be downloaded from the usual location.
Here's a list of changes, additions and fixes since 0.8.0013:
File format forwards compatibility has been broken. You will not be able to open files saved with 0.8.0050 on earlier versions.
This release contains many breaking changes and GHA libraries compiled for older version may not work anymore.
Grasshopper Binary files (*.gh) are now saved as compressed data.
Grasshopper Binary files (*.gh) are now the default format.
Support for ancient versions of the Text Panel (still called Post-It from back then) has been removed.
Support for ancient versions of the Path Mapper (still called Path Lexer from back then) has been removed.
Placeholders for ancient versions of the Graph Mapper have been removed.
Gradient input parameters now show state tag icons (Reversed, Flatten etc.).
Geometry Cache name changes are now updated on every key press.
Geometry Cache name changes can now be cancelled with Escape.
Geometry Cache name changes can now be undone.
Mesh|Mesh intersection component now uses a different algorithm. The old behaviour is still available from the component menu.
Warning and Error balloons are now drawn as part of a Canvas Widget and will no longer show up in the Hi-Res image export.
Galapagos now accepts multiple fitness values. The true fitness will be the average of the collection.
Galapagos wires are drawn much fainter when the Galapagos object is unselected.
Medium fast redraw mode in Galapagos now immediately redraws instead of at the end of each generation.
Redesigned all Grasshopper file format icons and added larger size icons for high-dpi explorer views.
Redesigned the Most Recently Used files menu, it should now display much quicker.
Compass widget has been rewritten in an attempt to increase display performance.
Added preferences section for Compass widget.
Added preferences section for Align widget.
Added preferences section for Default Preview colours.
Added preferences section for Document Preview colours.
Added preferences section for the Most Recently Used files menu.
The Area component now accepts Breps, Meshes and Planar Closed Curves.
The Area Centroid component now accepts Breps, Meshes and Planar Closed Curves.
The Volume component now accepts Breps and Meshes.
The Volume Centroid component now accepts Breps and Meshes.
Added Merge Faces component (Surface.Util panel).
Added a Mesh Smooth component (Mesh.Util panel).
Added a Curve Seam component (Curve.Util panel).
Added Interpolate Curve With Tangents component (Curve.Spline dropdown).
Added GrasshopperFolders command to open Settings, Components and UserObject folders without loading the core plugin.
The window that reports on certain Loading Errors now has a Copy button.
Added Simplify post-process filter to parameters (in addition to Reverse, Flatten and Graft).
Parameter post processes (Reverse, Flatten, Graft & Simplify) can now also be assigned to output parameters.
Version History window now has formatting (not happy with this, I'm working on something better).
The Process Info window is gone.
Main menu has been redesigned.
Canvas toolbar has been redesigned.
Canvas context menu has been replaced by a Radial Menu.
Canvas now has a radial menu which will pop up on Middle Mouse Button clicks.
It's possible to switch between Radial and Legacy menus in the Preferences (Interface.Canvas section).
'Save As Copy' feature has been replaced by 'Save Backup' which is a GUI-less save including date+time stamp.
Added a 'Show in Folder' item to the File menu.
AutoSave settings are no longer available from the File menu, you now need to use the Preferences.
Selection shifts now also modify the view so you can use Ctrl+Left and Ctrl+Right to navigate up and downstream.
Mesh Edge display can now be toggled with Ctrl+M.
Preview modes now have shortcuts (Ctrl+1 = no preview, Ctrl+2 = wireframe, Ctrl+3 = shaded).
Solution States now have a default name.
Data Viewer window now responds to all required events.
Data Viewer window can now handle input and output parameters as well.
Canvas Navigation pane can now be dragged using the icon in the upper left corner.
The Persistent Data Editor has been redesigned.
It's now possible to select multiple items in the Persistent Data Editor list and edit their properties.
It's now possible to drag multiple items at the same time in the Persistent Data Editor list.
Item addition to the Persistent Data Editor is much improved.
The Persistent Data Editor is now non-modal.
The Canvas would remain black upon maximizing the Rhino window, this is fixed.
Sliders would cause multiple updates under certain conditions, this is fixed.
Digit Scrollers would cause multiple updates under certain conditions, this is fixed.
Pipes were inside out. This is fixed.
The curve component would not adjust invalid nurbs degrees, this is fixed.
Curves referencing Brep edges failed to load, this is fixed.
Points referencing Brep edges failed to load, this is fixed.
Referenced dlls in the VB/C# components sometimes resulted in invalid imports statements, this is fixed.
Pasting geometry in Rhino would cause a recompute of the Grasshopper solution, this is fixed.
Importing a file into the Rhino document would cause a recompute of the Grasshopper solution, this is fixed.
Galapagos would trigger superfluous solutions, this is fixed.
Mesh Solid Difference had a wrong name and description, this is fixed.
Several menu items were not greyed out despite not being usable, this is fixed.
The position and size of the Grasshopper window failed to get stored on Rhino shutdown, this is fixed.
The Persistent Data Editor would crash on parameters that did not support data proxies, this is fixed.
I'll add some additional information regarding some of the new UI features in subsequent posts.
--
David Rutten
david@mcneel.com
Poprad, Slovakia…
rmation?" I know that this can already be accomplished using the brilliant Kangaroo plugin, but I wanted a simpler and faster (yet still accurate) single component that could replicate this unique curve using a variety of inputs: the length of the rod/wire, the width/distance between the endpoints, the height of the bend, and the tangent angle at the start. I also wanted make the unknowns (such as height if only length and width are known) easily accessible for plugging into additional components.
The resulting script, being an all-in-one solution, is somewhat unwieldy, but it could easily be broken down into smaller components (custom .gha's which I don't have the ability to code). If someone wants to tackle this, please do! I'm not an expert coder by any means, and as this was only my second time diving into Grasshopper scripting, if the script seems somewhat strange, that's probably why. I did try to comment the code pretty well though. Here's the full description:
--------------------------------------------------
DESCRIPTION: This beast creates the so-called 'elastica curve', the shape a long, thin rod or wire makes when it is bent elastically (i.e. not permanently). In this case, force is assumed to only be applied horizontally (which would be in line with the rod at rest) and both ends are assumed to be pinned or hinged meaning they are free to rotate (as opposed to clamped, when the end tangent angle is fixed, usually horizontally). An interesting finding is that it doesn't matter what the material or cross-sectional area is, as long as they're uniform along the entire length. Everything makes the same shape when bent as long as it doesn't cross the threshold from elastic to plastic (permanent) deformation (I don't bother to find that limit here, but can be found if the yield stress for a material is known).
Key to the formulas used in this script are elliptic integrals, specifically K(m), the complete elliptic integral of the first kind, and E(m), the complete elliptic integral of the second kind. There was a lot of confusion over the 'm' and 'k' parameters for these functions, as some people use them interchangeably, but they are not the same. m = k^2 (thus k = Sqrt(m)). I try to use the 'm' parameter exclusively to avoid this confusion. Note that there is a unique 'm' parameter for every configuration/shape of the elastica curve.
This script tries to find that unique 'm' parameter based on the inputs. The algorithm starts with a test version of m, evaluates an expression, say 2*E(m)/K(m)-1, then compares the result to what it should be (in this case, a known width/length ratio). Iterate until the correct m is found. Once we have m, we can then calculate all of the other unknowns, then find points that lie on that curve, then interpolate those points for the actual curve. You can also use Wolfram|Alpha as I did to find the m parameter based on the equations in this script (example here: http://tiny.cc/t4tpbx for when say width=45.2 and length=67.1).
Other notes:
* This script works with negative values for width, which will creat a self-intersecting curve (as it should). The curvature of the elastica starts to break down around m=0.95 (~154°), but this script will continue to work until M_MAX, m=0.993 (~169°). If you wish to ignore self-intersecting curves, set ignoreSelfIntersecting to True
* When the only known values are length and height, it is actually possible for certain ratios of height to length to have two valid m values (thus 2 possible widths and angles). This script will return them both.
* Only the first two valid parameters (of the required ones) will be used, meaning if all four are connected (length, width or a PtB, height, and angle), this script will only use length and width (or a PtB).
* Depending on the magnitude of your inputs (say if they're really small, like if length < 10), you might have to increase the constant ROUNDTO at the bottom
REFERENCES: {1} "The elastic rod" by M.E. Pacheco Q. & E. Pina, http://www.scielo.org.mx/pdf/rmfe/v53n2/v53n2a8.pdf {2} "An experiment in nonlinear beam theory" by A. Valiente, http://www.deepdyve.com/lp/doc/I3lwnxdfGz {3} "Snap buckling, writhing and Loop formation In twisted rods" by V.G.A. GOSS, http://myweb.lsbu.ac.uk/~gossga/thesisFinal.pdf {4} "Theory of Elastic Stability" by Stephen Timoshenko, http://www.scribd.com/doc/50402462/Timoshenko-Theory-of-Elastic-Stability (start on p. 76)
INPUT: PtA - First anchor point (required) PtB - Second anchor point (optional, though 2 out of the 4--length, width, height, angle--need to be specified) [note that PtB can be the same as PtA (meaning width would be zero)] [also note that if a different width is additionally specified that's not equal to the distance between PtA and PtB, then the end point will not equal PtB anymore] Pln - Plane of the bent rod/wire, which bends up in the +y direction. The line between PtA and PtB (if specified) must be parallel to the x-axis of this plane
** 2 of the following 4 need to be specified ** Len - Length of the rod/wire, which needs to be > 0 Wid - Width between the endpoints of the curve [note: if PtB is specified in addition, and distance between PtA and PtB <> width, the end point will be relocated Ht - Height of the bent rod/wire (when negative, curve will bend downward, relative to the input plane, instead) Ang - Inner departure angle or tangent angle (in radians) at the ends of the bent rod/wire. Set up so as width approaches length (thus height approaches zero), angle approaches zero
* Following variables only needed for optional calculating of bending force, not for shape of curve. E - Young's modulus (modulus of elasticity) in GPa (=N/m^2) (material-specific. for example, 7075 aluminum is roughly 71.7 GPa) I - Second moment of area (or area moment of inertia) in m^4 (cross-section-specific. for example, a hollow rod would have I = pi * (outer_diameter^4 - inner_diameter^4) / 32 Note: E*I is also known as flexural rigidity or bending stiffness
OUTPUT: out - only for debugging messages Pts - the list of points that approximate the shape of the elastica Crv - the 3rd-degree curve interpolated from those points (with accurate start & end tangents) L - the length of the rod/wire W - the distance (width) between the endpoints of the rod/wire H - the height of the bent rod/wire A - the tangent angle at the (start) end of the rod/wire F - the force needed to hold the rod/wire in a specific shape (based on the material properties & cross-section) **be sure your units for 'I' match your units for the rest of your inputs (length, width, etc.). Also note that the critical buckling load (force) that makes the rod/wire start to bend can be found at height=0
THANKS TO: Mårten Nettelbladt (thegeometryofbending.blogspot.com) Daniel Piker (Kangaroo plugin) David Rutten (Grasshopper guru) Euler & Bernoulli (the O.G.'s)
--------------------------------------------------
Edit: More on the math behind this here.
Cheers,
Will
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Added by Will McElwain at 4:08pm on February 26, 2014
lly it should not make much of a difference - random number generation is not affected, mutation also is not. crossover is a bit more tricky, I use Simulated Binary Crossover (SBX-20) which was introduced already in 1194:
Deb K., Agrawal R. B.: Simulated Binary Crossover for Continuous Search Space, inIITK/ME/SMD-94027, Convenor, Technical Reports, Indian Institue of Technology, Kanpur, India,November 1994
Abst ract. The success of binary-coded gene t ic algorithms (GA s) inproblems having discrete sear ch sp ace largely depends on the codingused to represent the prob lem variables and on the crossover ope ratorthat propagates buildin g blocks from pare nt strings to childrenst rings . In solving optimization problems having continuous searchspace, binary-co ded GAs discr et ize the search space by using a codingof the problem var iables in binary st rings. However , t he coding of realvaluedvari ables in finit e-length st rings causes a number of difficulties:inability to achieve arbit rary pr ecision in the obtained solution , fixedmapping of problem var iab les, inh eren t Hamming cliff problem associatedwit h binary coding, and processing of Holland 's schemata incont inuous search space. Although a number of real-coded GAs aredevelop ed to solve optimization problems having a cont inuous searchspace, the search powers of these crossover operators are not adequate .In t his paper , t he search power of a crossover operator is defined int erms of the probability of creating an arbitrary child solut ion froma given pair of parent solutions . Motivated by t he success of binarycodedGAs in discret e search space problems , we develop a real-codedcrossover (which we call the simulated binar y crossover , or SBX) operatorwhose search power is similar to that of the single-point crossoverused in binary-coded GAs . Simulation results on a number of realvaluedt est problems of varying difficulty and dimensionality suggestt hat the real-cod ed GAs with t he SBX operator ar e ab le to perform asgood or bet t er than binary-cod ed GAs wit h t he single-po int crossover.SBX is found to be particularly useful in problems having mult ip le optimalsolutions with a narrow global basin an d in prob lems where thelower and upper bo unds of the global optimum are not known a priori.Further , a simulation on a two-var iable blocked function showsthat the real-coded GA with SBX work s as suggested by Goldberg
and in most cases t he performance of real-coded GA with SBX is similarto that of binary GAs with a single-point crossover. Based onth ese encouraging results, this paper suggests a number of extensionsto the present study.
7. ConclusionsIn this paper, a real-coded crossover operator has been develop ed bas ed ont he search characte rist ics of a single-point crossover used in binary -codedGAs. In ord er to define the search power of a crossover operator, a spreadfactor has been introduced as the ratio of the absolute differences of thechildren points to that of the parent points. Thereaft er , the probabilityof creat ing a child point for two given parent points has been derived forthe single-point crossover. Motivat ed by the success of binary-coded GAsin problems wit h discrete sear ch space, a simul ated bin ary crossover (SBX)operator has been develop ed to solve problems having cont inuous searchspace. The SBX operator has search power similar to that of the single-po intcrossover.On a number of t est fun ctions, including De Jong's five te st fun ct ions, ithas been found that real-coded GAs with the SBX operator can overcome anumb er of difficult ies inherent with binary-coded GAs in solving cont inuoussearch space problems-Hamming cliff problem, arbitrary pr ecision problem,and fixed mapped coding problem. In the comparison of real-coded GAs wit ha SBX operator and binary-coded GAs with a single-point crossover ope rat or ,it has been observed that the performance of the former is better than thelatt er on continuous functions and the performance of the former is similarto the lat ter in solving discret e and difficult functions. In comparison withanother real-coded crossover operator (i.e. , BLX-0 .5) suggested elsewhere ,SBX performs better in difficult test functions. It has also been observedthat SBX is particularly useful in problems where the bounds of the optimum
point is not known a priori and wher e there are multi ple optima, of whichone is global.Real-coded GAs wit h t he SBX op erator have also been tried in solvinga two-variab le blocked function (the concept of blocked fun ctions was introducedin [10]). Blocked fun ct ions are difficult for real-coded GAs , becauselocal optimal points block t he progress of search to continue towards t heglobal optimal point . The simulat ion results on t he two-var iable blockedfunction have shown that in most occasions , the sea rch proceeds the way aspr edicted in [10]. Most importantly, it has been observed that the real-codedGAs wit h SBX work similar to that of t he binary-coded GAs wit h single-pointcrossover in overcoming t he barrier of the local peaks and converging to t heglobal bas in. However , it is premature to conclude whether real-coded GAswit h SBX op erator can overcome t he local barriers in higher-dimensionalblocked fun ct ions.These results are encour aging and suggest avenues for further research.Because the SBX ope rat or uses a probability distribut ion for choosing a childpo int , the real-coded GAs wit h SBX are one st ep ahead of the binary-codedGAs in te rms of ach ieving a convergence proof for GAs. With a direct probabilist ic relationship between children and parent points used in t his paper,cues from t he clas sical stochast ic optimization methods can be borrowed toachieve a convergence proof of GAs , or a much closer tie between the classicaloptimization methods and GAs is on t he horizon.
In short, according to the authors my SBX operator using real gene values is as good as older ones specially designed for discrete searches, and better in continuous searches. SBX as far as i know meanwhile is a standard general crossover operator.
But:
- there might be better ones out there i just havent seen yet. please tell me.
- besides tournament selection and mutation, crossover is just one part of the breeding pipeline. also there is the elite management for MOEA which is AT LEAST as important as the breeding itself.
- depending on the problem, there are almost always better specific ways of how to code the mutation and the crossover operators. but octopus is meant to keep it general for the moment - maybe there's a way for an interface to code those things yourself..!?
2) elite size = SPEA-2 archive size, yes. the rate depends on your convergence behaviour i would say. i usually start off with at least half the size of the population, but mostly the same size (as it is hard-coded in the new version, i just realize) is big enough.
4) the non-dominated front is always put into the archive first. if the archive size is exceeded, the least important individual (the significant strategy in SPEA-2) are truncated one by one until the size is reached. if it is smaller, the fittest dominated individuals are put into the elite. the latter happens in the beginning of the run, when the front wasn't discovered well yet.
3) yes it is. this is a custom implementation i figured out myself. however i'm close to have the HypE algorithm working in the new version, which natively has got the possibility to articulate perference relations on sets of solutions.
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re are major changes and enhancements.
HONEYBEE
More Flexible Workflow - Many small modifications were made to support a more flexible workflow, such as the ability to separate a zone created with masses2Zones into editable HBSrfs that can be recombined. For the energy components, it is now possible to plug custom constructions directly into the components that set the zone constructions without writing them first into the library. For the daylighting components it is now possible to change all of the materials of specific surface types at once.
Support for Complex Geometry - Many small bugs for complex geometry have been fixed including the ability to import energy results correctly for curved NURBS surfaces as well as unconventional window configurations. Also, the intersectMasses component now almost always succeeds in splitting all of the surfaces of adjacent zones, no matter how complex the intersection is.
Automatic Download Issues Fixed - Many users who faced issues with not having “gendaymtx.exe” or who had trouble syncing with our github know that we faced an issue with automatic background downloads.
Air Walls - Honeybee EnergyPlus models now officially support air walls (or virtual partitions) in a basic implementation. Now, any time that you use the air wall construction or set a surface type to “air wall,” the air between adjacent zones will be automatically mixed. At present, this mixing is just a constant flow based on the surface area between zones connected by air walls multiplied by an adjustable “flow factor.” It is important to stress that this basic air mixing is not with the EnergyPlus Airflow Network, although the groundwork laid in this release will eventually allow for the implementation of the Airflow Network in future releases. As such, this present air mixing is only suitable for multi-zone conditions where there is not significant buoyancy-driven flow between zones.
Natural Ventilation - To go along with the new potential introduced by air walls, there has been a basic implementation of EnergyPlus’s natural ventilation objects in a new component called “Set EP Airflow”. The current setup allows for three possible types of natural ventilation: 1) natural ventilation through windows (with auto-calculated flow based on window area, outdoor wind speed/direction, and stack effects), 2) custom wind and stack objects that can be used to model things such as chimneys off of single zones, and 3) constant, fan-driven natural ventilation.
Additional Thermal Mass - The capability to add additional thermal mass to zones has been added. This is useful for factoring in the mass of indoor furniture or heavy interior objects such as chimneys.
New Utility Components - Abraham has added a couple of useful components to help calculate lighting loads based on bulb types and target lighting levels as well as a converter from ACH to the m3/s-m2 that the other HB components accept. Along this vein, there is also a component for adding in the resistance of Air Films to HB constructions.
Improved and Editable Ideal Air Loads System - The EnergyPlus Ideal Air System now goes through an automatic sizing period at the start of the simulation based on the extreme weeks of the weather file. Furthermore, the ability to adjust many of the parameters of the ideal air loads system have been added with a new “Set Ideal Air Loads Parameters” component. The component allows you to add in heat recovery, air side economizers and demand-controlled ventilation.
OpenStudio Export Update - The OpenStudio workflow is still largely under development but this release includes a version with a working VAV and PTHP system template for those curious with experimenting. Note that not all of the new features available for the basic “Run Energy Simulation” component are available for the OpenStudio component (such as air walls, natural ventilation, or additional thermal mass).
Microclimate/Indoor Comfort Maps - Blossoming from initial experiments with the radiant temperature map, a workflow for looking into sub-zone microclimate and indoor comfort has been initiated. All components for this are presently under the Honeybee WIP tab but, over the next month, they will be completing their development phase and moving into the rest of the tabs. If you are interested in testing when they are ready, please let Chris know. For a teaser video of the intended capabilities, see this video: (https://www.youtube.com/watch?v=fNylb42FPIc&list=UUc6HWbF4UtdKdjbZ2tvwiCQ)
LADYBUG
Monthly Bar Chart - After much demand from multiple parties, a new component to create monthly bar and line charts has been added. The component is particularly useful for plotting the outputs of the “Average Data” component like monthly EPW data or averaged monthly-per hour data. It also supports daily data and any type of Energy simulation results.
Wind Profile - To go along with the new capabilities of natural ventilation in Honeybee, Ladybug now has a fully fleshed-out Wind Profile component that allows you to visualize how wind speed changes with height in relation to your building geometry. The component is geared to understanding the conditions of prevailing wind and will be useful in the future for setting up CFD models. Credit goes to Djordje Spasic for adding in all of the new capabilities. In a similar vein, the appearance of the wind rose has also been improved thanks to suggestions from Alejandra Menchaca.
Faster Solar Adjusted Temperature - Thanks to the SolarCal method from the Center for the Built Environment at UC Berkeley (http://escholarship.org/uc/item/89m1h2dg), the solar adjusted temperature component now includes an option for a much faster calculation that produces results that are very close to those originally obtained with the genCumSky component. Instead of using the cumulative sky, the component can now accept the direct and diffuse radiation from the ImportEPW component. Over a whole year, this essentially takes a calculation that used to be a half-hour and shrinks it down to 10 seconds. Thanks again to those at UC Berkeley for keeping their work open source!
Instructions - Last but not the least, [It took me almost two years to understand this but finally] we have a text file that describes the installation step by step and is way easier to modify than a video. You can find it in the zip file. Credit goes to Chris!
We also want to welcome Anton, Patrick and Sandeep to the team. Anton has kicked off his development by working on a component to import and visualize epw ground temperature data and he will be continuing to develop components to bring in reliable precipitation data to Ladybug. With this basis, he will continue to implement Honeybee components for ground heat storage, earth tubes, rain collection and hot water systems. Patrick and Sandeep are working on integration of Honeybee to Energy Performance Calculator.
As always let us know your comments and suggestions.
Enjoy!…