e chosen to dive into Grasshopper. I’m about 6 months in. If some of my comments are completely off, please take that to mean that a feature is too inaccessible to a newish user rather that it’s just missing, as I may have stated.
One of my primary pain points is this. Things that can be done in other programs are invariably easier in other programs. This is a big enough issue that I doubt there’s an easy solution that an armchair qb like myself can offer up.
The interface:
I’ve used a lot of 3D programs. I’ve never encountered one as difficult as grasshopper. 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. Yet PTC (Parametric Technology Corp.) has been doing parametric design software since 1985 and has a far cleaner and more intuitive interface. So does SolidWorks, Inventor, CATIA, NX, and a bunch of others.
In the early 2000's, when parametric design software was all the rage, McNeel stated quite strongly the Rhino would remain a direct modeler and would not become a parametric modeler. Trends come. Trends go. And the industry has been swinging back to direct modeling. So McNeel’s decision was probably ok. But I have to wonder if part of McNeel’s reluctance to incorporate some of the tried and proven ideas of other parametric packages doesn't have roots in their earlier declaration to not incorporate parametrics.
A Visual Programming Language:
I read a lot about the awesomeness and flexibility of Grasshopper being a visual programming language. Let’s be clear, this is DOS era speak. I believe GH should continue to have the ability to be extended and massaged with code, as most design programs do. But as long as this is front and center, GH will remain out of reach to the average designer.
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.
Sliders:
I hate sliders. I understand them, but I hate ‘em. I think they should be optional. Ya, I know I can r-click on the N of a component and set the integer. It’s a pain, and it gives no feedback. The “N” should turn into the number if set. AAAnd, sliders should be context sensitive. I like that the name of a slider changes when I plug it into something. But if I plug it into something that'll only accept a 1, a 2, or a 3, that slider should self set accordingly. I shouldn't be able to plug in a “50” and have everything after turn red.
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.
And this item I’m guessing on. I’m not yet good enough at GH to know if this may have adverse effects. Reverse, Flatten, Graft, etc.; could these be context sensitive? Could some of these items disappear if they are contextually inappropriate or gray out if they're unlikely?
Tighter integration with Rhino:
I'm not entirely certain what this would look like. Currently my work flow entails baking, making a few Rhino edits, and reinserting into GH. I question the whole baking thing, btw. Why isn't it just live geometry? That’s how other parametric apps work. Maybe add more Rhino functionality to GH. GH has no 3D offset. I have to bake, offsetserf, and reinsert the geometry. I’m currently looking at the “Geometry Cache” and “Geometry Pipeline” components to see if they help. But I haven't been able to figure it out. Which leads me to:
Update all of the documentation:
I'm guessing this is an in process thing and you're working toward rolling GH from 0.9.00075 to 1.0. GH was being updated nearly weekly earlier this year. Then it suddenly stopped. If we're talking weeks before a full release, so be it. But if we're looking at something longer, a documentation update would help a lot. Geometry Cache and Geometry Pipeline’s help still read “This is the autogenerated help topic for this object. Developers: override the HtmlHelp_Source() function in the base class to provide custom help.” This does not help. And the Grasshopper Primer 2nd Ed. was written for GH 0.60007.
Grasshopper is fundamentally a 2D program:
I know you'll disagree completely, but I'm sticking to this. How else could an omission like offsetsurf happen? Pretty much every 3D program in existence has this. I’m sure I can probably figure out how to deconstruct the breps, join the curves, loft, trim, and so forth. But does writing an algorithm to do what all other 3D programs do with a dialog box seem reasonable? I'm sure if you go command by command you'll find a ton on such things.
If you look at the vast majority of things done in GH, you'll note that they're mostly either flat or a fundamentally 2D pattern on a warped surface.
I've been working on a part that is a 3D voronoi trimmed to a 3D model. I've been trying to turn the trimmed voronoi into legitimate geometry for over a month without success.
http://www.grasshopper3d.com/profiles/blogs/question-voronoi-3d-continued
I’ve researched it enough to have found many others have had the exact same problem and have not solved it. It’s really not that conceptually difficult. But GH lacks the tools.
Make screen organization easier:
I have a touch of OCD, and I like my GH layout to flow neatly. Allow input/output nodes to be re-ordered. This will allow a reduction in crossed wires. Make the wire positions a bit more editable. I sometimes use a geometry component as a wire anchor to clean things up. Being able to grab a wire and pull it out of the way would be kinda nice.
I think GH has some awesome abilities. I also think accessing those abilities could be significantly easier.
~p…
me of the dimensions that changed ( become Diagonal after they were Vertical or Horizontal)
I sometime use Record History in rhino for saving time, but when I change some points of curves or trim curves , I have problems with dimensions (see the two pictures below).
Problem 2 :
After trimming , only two dimensions should be changed depending on their place in changed curves . But what happens is that all the dimensions become crazy!!!!!!
I always use Aligned dimension in rhino. Now I know that dimensionsdo not exist in grasshopper. So I ask you if we have expertise in BV , C#, can we create a script for dimensions or is it impossible ??
If we can , I only need Aligned dimension.
I hope that I find or create a script that can define all points: start and end of curve ribs and create dimensions from grasshopper to rhino directly with or without the ability to change automatically .
Thank you
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mesh by an infinite plane
Namespace: Rhino.GeometryAssembly: RhinoCommon (in RhinoCommon.dll) Version: 5.0.15006.0 (5.0.20693.0)
Syntax
C#
public Mesh[] Split( Plane plane )
Visual Basic
Public Function Split ( _ plane As Plane _ ) As Mesh()
Parameters
plane
Type: Rhino.Geometry..::..Plane[Missing <param name="plane"/> documentation for "M:Rhino.Geometry.Mesh.Split(Rhino.Geometry.Plane)"]
Return Value
[Missing <returns> documentation for "M:Rhino.Geometry.Mesh.Split(Rhino.Geometry.Plane)"]
See Also
Mesh Class
Rhino.Geometry Namespace
Last updated 3 June 2011 - Robert McNeel and Associates
Send comments on this topic to steve@mcneel.com
Report wishes and bugs: https://github.com/mcneel/rhinocommon/issues
Is this the function?
I have a VB component with this:
a = rhino.Geometry.Mesh.CreateBooleanSplit(x, y)
but this is a boolean split, so I have only one mesh, with the intersection. I would like to have several splitted meshes.
Thank you in advance again.
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,with OpenfoamV1612+ in Windows 10 64bit.The blockmesh worked good.And the snappyhexmesh crashed in the process.My computer memory is not enough? Or some settings wrong?Could you help me solve this question?/---------------------------------------------------------------------------| ========= | || \ / F ield | OpenFOAM: The Open Source CFD Toolbox || \ / O peration | Version: v1612+ || \ / A nd | Web: www.OpenFOAM.com || \/ M anipulation | |*---------------------------------------------------------------------------*/Build : v1612+Exec : snappyHexMeshDate : Aug 27 2017Time : 09:39:54Host : "default"PID : 13443Case : /home/ofuser/workingDir/butterfly/outdoor_airflownProcs : 1sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)allowSystemOperations : Allowing user-supplied system call operations
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //Create time
Create mesh for time = 0
Read mesh in = 2.14 s
Overall mesh bounding box : (-241.5472 -241.4418 0) (496.4376 536.2438 144.8633)Relative tolerance : 1e-06Absolute matching distance : 0.001081851
Reading refinement surfaces.Read refinement surfaces in = 0.01 s
Reading refinement shells.Refinement level 3 for all cells inside around_buildings_area.stlRead refinement shells in = 0 s
Setting refinement level of surface to be consistent with shells.For geometry outdoor_airflow.stl detected 0 uncached triangles out of 120Checked shell refinement in = 0 s
Reading features.Read features in = 0 s
Determining initial surface intersections
Edge intersection testing:Number of edges : 1684728Number of edges to retest : 1684728Number of intersected edges : 5583Calculated surface intersections in = 1.68 s
Initial mesh : cells:554112 faces:1684728 points:576779Cells per refinement level:0 554112
Adding patches for surface regions
Patch Type Region
outdoor_airflow:
6 wall buildings
Added patches in = 0.03 s
Edge intersection testing:Number of edges : 1684728Number of edges to retest : 0Number of intersected edges : 5583Selecting decompositionMethod none
Refinement phase
Found point (127.4452 147.401 72.43167) in cell 402042 on processor 0
Surface refinement iteration 0
Marked for refinement due to surface intersection : 8820 cells.Determined cells to refine in = 3.87 sSelected for refinement : 8820 cells (out of 554112)Edge intersection testing:Number of edges : 1883850Number of edges to retest : 250376Number of intersected edges : 21198Refined mesh in = 1.77 sAfter refinement surface refinement iteration 0 : cells:615852 faces:1883850 points:652499Cells per refinement level:0 5452921 70560
Surface refinement iteration 1
Marked for refinement due to surface intersection : 38502 cells.Determined cells to refine in = 0.04 sSelected for refinement : 40392 cells (out of 615852)Edge intersection testing:Number of edges : 2787132Number of edges to retest : 1118049Number of intersected edges : 85655Refined mesh in = 3.17 sAfter refinement surface refinement iteration 1 : cells:898596 faces:2787132 points:990317Cells per refinement level:0 5432351 486812 306680
Surface refinement iteration 2
Marked for refinement due to surface intersection : 159213 cells.Determined cells to refine in = 0.1 sSelected for refinement : 168471 cells (out of 898596)Edge intersection testing:Number of edges : 6576117Number of edges to retest : 4737635Rhino Model and GH files is in t'he zip file.Please help me solve this question!~~…
rtitions." (http://wias-berlin.de/software/index.jsp?id=TetGen&lang=1)
To continue with my wrapping career, TetRhino (or Tetrino) is a .NET wrapper for the well-known and pretty amazing TetGen mesh tetrahedralization program. It provides one new GH component for discretizing or remeshing objects using TetGen. Basic tetrahedralization functionality is exposed with a few different output types that can be controlled. At the moment, the only control for tetrahedra sizes is the minimum ratio, which is controlled by a slider. This is hardcoded to always be above 1.0-1.1, as it is very easy to generate a LOT of data (and crash)...
The libs are divided again into different modules to allow flexibility and fun with or without Rhino and GH, so have fun. All 4 libs should be placed in a folder (maybe called 'tetgen') in your GH libraries folder. Remember to unblock.
Once again, the libs are provided as-is, with no guarantee of support for now, as I use them internally and do not intend to develop this into a shiny, polished plug-in. If there is enough interest, I can tidy up the code-base and upload it somewhere if someone more savvy than me wants to play.
TetgenGH.gha - Grasshopper assembly which adds the 'Tetrahedralize' component to Mesh -> Triangulation.
TetgenRC.dll - RhinoCommon interface to the Tetgen wrapper.
TetgenSharp.dll - dotNET wrapper for Tetgen.
TetgenWrapper.dll - Actual wrapper for Tetgen.
Obviously, credit where credit is due for this excellent and tiny piece of software:
"The development of TetGen is executed at the Weierstrass Institute for Applied Analysis and Stochastics in the research group of Numerical Mathematics and Scientific Computing." See http://wias-berlin.de/software/index.jsp?id=TetGen&lang=1 for more details about TetGen.
To wrap up, some notes about the inputs:
These are the possible integer Flags (F) values and resultant outputs for the GH component:
0 - Output M yields a closed boundary mesh. Useful for simply remeshing your input mesh.
1 - Output M yields a list of tetra meshes.
2 - Output I yields a DataTree of tetra indices, grouped in lists of 4. Output P yields a list of points to which the tetra indices correspond.
3 - Output I yields a DataTree of edge indices, grouped in lists of 2. Output P yields a list of points to which the edge indices correspond. Useful for lots of things, very easy to create lines from this to plug into K2 or something for some ropey FEA (or not so ropey!) ;)
As this component can potentially create a LOT of data, especially with dense meshes, care should be taken with the MinRatio (R) input. This will try to constrain the tetra to be more or less elongated, which also means that the lower this value gets, the more tetra need to be added to satisfy this constraint. Start with very high values and lower them until satisfactory.
Hopefully shouldn't be an issue, but it's possible that you need the 2015 Microsoft C++ Redistributable.
Happy tetrahedralizing...
UPDATE: The tetgen.zip has been updated with some fixes.
UPDATE2: This is now available on Food4Rhino: http://www.food4rhino.com/app/tetrino
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Added by Tom Svilans at 1:27am on October 24, 2017
Karamba.
I am using your plug-in for normal forces evaluation in the transvere wires and spreaders of a sailboat. Mast is solved in another way, so I am not taking forces from Karamba in that case.
Basing on the forces value an adequate wire size (diameter) is choosen. Then masses of wires are being calculated. Loads (forces) on longitudinal wires are calculated without Karamba. The problem is when choosing transverse wires’ mass minimization as a criteria, the Octopus doesn’t get any results - is changing the sliders (genes) too fast for Karamba to calculate the forces (so Octopus gets only nulls):
When minimization of a e.g. longitudinal wires’ mass (calculated without Karamba) is taken as a criteria Octopus works fine.
Which suggests that the problem is in interaction of two plug-ins.
Any ideas how to avoid that problem?
Thanks,
M.
Below some screenshots of definition part with Karamba:
1675×807 200 K
image.png1680×789 398 KB
Despite the ‘orange warning’ the values are correct (double checked with other software).However I don't know why does it say that there is a part that can move freely without deformation,as the model looks like this:
image.png1239×343 55.5 KB
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ndard length elements without any cutting, and using only simple connections, such as cable ties or scaffold swivel couplers.
To summarize the approach I present here:
Design an initial shape
Remesh this form so that the edges are all roughly the length of the tubes we will use to build the structure
Rotate and extend the edges of this mesh to create the crossings
Apply a relaxation to optimize the positions of the tubes for tangency
demo_reciprocal_structures.gh
Initial form
In this example I show how to apply this system to a simple sphere. You can replace this with any arbitrary shape. It can be open or closed, and have any topology.
Remeshing
The new ReMesher component takes an input mesh, and a target edge length, and iteratively flips/splits/collapses edges in order to achieve a triangulated mesh of roughly equal edge lengths.
Press the Reset button to initialize, then hold down the F5 key on your keyboard to run several iterations until it has stabilized. (F5 just recomputes the solution, and this can be a quick alternative to using a timer)
Once the remeshing is complete, bake the result into Rhino and reference it into the next part of the definition (I recommend doing this rather than connecting it directly, so that you don't accidentally alter the mesh and recompute everything downstream later).
Alternatively you can create your mesh manually, or using other techniques.
Rotate and Extend
We generate the crossings using an approach similar to that described by Tomohiro Tachi for tensegrity structures here:
http://www.tsg.ne.jp/TT/cg/FreeformTensegrityTachiAAG2012.pdf
Using the 'Reciprocal' component found in the Kangaroo mesh tab, each edge is rotated about an axis through its midpoint and normal to the surface, then extended slightly so that they cross over.
By changing the angle you can change whether the fans are triangular or hexagonal, and clockwise or counter-clockwise.
Choose values for the angle and scaling so that the lines extend beyond where they cross, but not so far that they clash with the other edges.
Note that each rod has 4 crossings with its surrounding rods.
There are multiple possibilities for the over/under pattern at each 'fan', and which one is used affects the curvature:
A nice effect of creating the pre-optimization geometry by rotating and extending mesh edges in this way is that the correct over/under pattern for each fan gets generated automatically.
Optimization for tangency
We now have an approximate reciprocal structure, where the lines are the centrelines of our rods, but the distances between them where they cross vary, so we would not actually be able to easily connect the rods in this configuration.
To attach the rods to form a structure, we want them to be tangent to one another. A pair of cylinders is tangent if the shortest line between their centrelines is equal to the sum of their radii:
Achieving tangency between all crossed rods in the structure is a tricky problem - if we move any one pair of rods to be tangent, we usually break the tangency between other pairs, and because there are many closed loops, we cannot simply start with one and solve them in order.
Therefore we use a dynamic relaxation approach, where forces are used to solve all the tangency constraints simultaneously, and over a number of iterations it converges to a solution where they are all met. The latest Kangaroo includes a line-line force, which can be used to pull and push pairs of lines so that they are a certain distance apart. Each rod is treated as a rigid body, so forces applied along its length will cause it to move and rotate.
The reciprocal component uses Plankton to find the indices of which lines in the list cross, which are then fed into the force for Kangaroo. We also use springs to keep each line the same length.
If the input is good, when we run the relaxation (by double clicking Kangaroo and pressing play), the rods should move only a little. We can see whether tangency has been achieved by looking at the shortest distance between the centerlines of the crossing rods. When this is twice the rod radius, they are tangent. Wait for it to solve to the desired degree of accuracy (there's no need to wait for 1000ths of a millimeter), and then press pause on the Kangaroo controller and bake the result.
The radius you choose for the pipes, curvature of the form and length of the edges all affect the result, and at this stage you may need to tweak these input values to get a final result you are happy with. If you find the rods are not reaching a stable solution but are sliding completely off each other, you might want to try adding weak AnchorSprings to the endpoints of the lines, to keep them from drifting too far from their original positions.
For previewing the geometry during relaxation I have used the handy Mesh Pipe component from Mateusz Zwierzycki, as it is much faster than using actual surface pipes.
To actually build this, you then need to extract the distances along each rod at which the crossings occur, and whether it crosses over or under, mark the rods accordingly, and assemble (If there is interest I will also clean up and post the definition for extracting this information). While this technique doesn't require much equipment, it does need good coordination and numbering!
There is also a ReciprocalStructure user object component that can be found in the Kangaroo utilities tab, which attempts to apply steps 3 and 4 automatically. However, by using the full definition you have more control and possibility to troubleshoot if any part isn't working.
The approach described here was first tested and refined at the 2013 Salerno Structural Geometry workshop, lead by Gennaro Senatore and myself, where we built a small pavilion using this technique with PVC tubes and cable ties. Big thanks to all the participants!
Finally - this is all very experimental work, and there are still many unanswered questions, and a lot of scope for further development of such structures. I think in particular - which of the relative degrees of freedom between pairs of rods are constrained by the connection (sliding along their length, bending, and twisting) and how this affects the structural behaviour would be interesting to examine further.
Steps 3 and 4 of the approach presented above would also work with quad meshes, which would have different stability characteristics.
There is also the issue of deformation of the rods - as the procedure described here solves only the geometric question of how to make perfectly rigid straight cylinders tangent. The approach could potentially be extended to adjust for, or make use of the flexibility of the rods.
I hope this is useful to somebody. Please let me know if you do have a go at building something using this.
Any further discussion on these topics is welcome!
Further reading on reciprocal structures:
http://vbn.aau.dk/files/65339229/Three_dimensional_Reciprocal_Structures_Morphology_Concepts_Generative_Rules.pdf
http://www3.ntu.edu.sg/home/cwfu/papers/recipframe/
http://albertopugnale.wordpress.com/2013/04/05/form-finding-of-reciprocal-structures-with-grasshopper-and-galapagos/
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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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can toggle these modes from either the Canvas Toolbar, the Remote Control Panel or via shortcuts Ctrl+1,2 or 3
These are pretty self explanatory so I will keep it brief:
No Preview will completely switch off the preview of the Grasshopper Objects in the Rhino Viewports.
Wireframe Preview similar to Disable Meshing will disable any render meshes but keep any curves or Edges visible.
Shaded Preview will shade the preview...
There are two more Icons in this section of the Display Menu:
Selected Only Preview
Preview Settings
Also available on the Canvas Toolbar.
Selected Only Preview is a useful feature for following what your definition is doing at stages along the process without having to switch all previews off and manually turning individual ones back on as you go.
Without Selected Only Preview Toggled
With Selected Only Preview Toggled:
Preview Settings is the area within Grasshopper where you can modify the colours - including transparency - Grasshopper uses to display objects in the Rhino Viewport.
The first thing you should do before altering any settings is to Drag the Default Colours onto the green plus sign to add them to the Presets. This will enable you to restore them easily.
For future reference the default settings are:
Normal = Hue: 0º, Sat: 100, Val: 59, A:100
Selected = Hue: 120º, Sat: 100, Val: 59, A:100
Apart from accounting for taste this feature is particularly useful for anyone that is colour blind[2]:
The way to restore a colour from the preset list is to drag it from the right hand panel to either the Normal or Selected option on the Left
[2] There is a very interesting discourse topic on the McNeel Forums about Red/Green Colour Blindness.
work carried out by Jørgen Holo
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