well, very similar input data must result in wildly different hashes. For example, imagine we have an algorithm which computes hashes of text, and the hashes it computes are all numbers between 0 and 999. We then apply this algorithm to a piece of text:
"When Spring comes back with rustling shade" = 385
So far so good. Now imagine we change the text slightly, for example by removing a single "l":
"When Spring comes back with rusting shade" = 973
Minor change -> very different hash. There are of course way more unique texts than there are numbers between 0 and 999. This must therefore mean that a lot of text will result in the same hash. For example "When Spring brings back blue days and fair." may also result in a hash of 385. Because of the pigeonhole principle, there is nothing to be done about this.
Now for the tricky bit. Hashes are often used to validate executable code. Say your friend James at MI6 sends you a small program that will allow you to eavesdrop on Angela Merkel, and -over the phone- he tells you the hashcode for that application. You can then hash the application yourself, verify that it indeed results in the same hashcode and then you know you can trust the executable.
But now Jack from the FBI intercepts the email and adds a few sneaky lines of code to the original application allowing him to determine from your internet search history with up to 95% accuracy whether you like extra cheese on your pizza. The application has now been tampered with, it can no longer be trusted and you should be able to figure this out as it will no longer result in the same hash code.
But wait! Some hashing algorithms are more secure than others. MD5 is now officially considered to be 'hacked' and it is no longer recommended for doing naughty spying. Specifically, Jack will be able to inject his own code in such a way that it does not result in a different hash. Instead, the SHA family of hashers are to be used, as it is not yet known how to trick these hashers.
This is where the problem comes in, because apparently the US government has forcefully disabled the use of MD5 for all purposes. This is a shame because I use it to quickly compare bitmap icons for identicalness so I only have to store an icon in memory once. There is no security hole due to this, because I'm not hashing secure data. MD5 is somewhat faster than SHA, and since I have to hash several hundred icons on Grasshopper start, I opted for the faster one.
(Very) long story short; you're hosed. Grasshopper uses MD5; USgov does not like; Grasshopper does not run on USgov computers.
I'll do some testing to see if I can switch to SHA and then we can see whether or not that solves the problem. This however will take a while as I'm going on a business trip next week and have yet to prepare my presentations.
--
David Rutten
david@mcneel.com…
Added by David Rutten at 12:06pm on March 31, 2014
ed file and code below:
Color ColorAt(Mesh mesh, int faceIndex, double t0, double t1, double t2, double t3) { // int rc = -1; var color = Rhino.Display.Color4f.Black;
if( mesh.VertexColors.Count != 0) { // test to see if face exists if( faceIndex >= 0 && faceIndex < mesh.Faces.Count ) { /// Barycentric quad coordinates for the point on the mesh /// face mesh.Faces[FaceIndex].
/// If the face is a triangle /// disregard T[3] (it should be set to 0.0).
/// If the face is /// a quad and is split between vertexes 0 and 2, then T[3] /// will be 0.0 when point is on the triangle defined by vi[0], /// vi[1], vi[2]
/// T[1] will be 0.0 when point is on the /// triangle defined by vi[0], vi[2], vi[3].
/// If the face is a /// quad and is split between vertexes 1 and 3, then T[2] will /// be -1 when point is on the triangle defined by vi[0], /// vi[1], vi[3]
/// and m_t[0] will be -1 when point is on the /// triangle defined by vi[1], vi[2], vi[3].
MeshFace face = mesh.Faces[faceIndex];
// Collect data for barycentric evaluation. Color p0, p1, p2;
if(face.IsTriangle) { p0 = mesh.VertexColors[face.A]; p1 = mesh.VertexColors[face.B]; p2 = mesh.VertexColors[face.C]; } else { if( t3 == 0 ) { // point is on subtriangle {0,1,2} p0 = mesh.VertexColors[face.A]; p1 = mesh.VertexColors[face.B]; p2 = mesh.VertexColors[face.C]; } else if( t1 == 0 ) { // point is on subtriangle {0,2,3} p0 = mesh.VertexColors[face.A]; p1 = mesh.VertexColors[face.C]; p2 = mesh.VertexColors[face.D]; //t0 = t0; t1 = t2; t2 = t3; } else if( t2 == -1 ) { // point is on subtriangle {0,1,3} p0 = mesh.VertexColors[face.A]; p1 = mesh.VertexColors[face.B]; p2 = mesh.VertexColors[face.D]; //t0 = t0; //t1 = t1; t2 = t3; } else { // point must be on remaining subtriangle {1,2,3} p0 = mesh.VertexColors[face.B]; p1 = mesh.VertexColors[face.C]; p2 = mesh.VertexColors[face.D]; t0 = t1; t1 = t2; t2 = t3; } }
/** double r = t0 * p0.FractionRed() + t1 * p1.FractionRed() + t2 * p2.FractionRed(); double g = t0 * p0.FractionGreen() + t1 * p1.FractionGreen() + t2 * p2.FractionGreen(); double b = t0 * p0.FractionBlue() + t1 * p1.FractionBlue() + t2 * p2.FractionBlue();
ON_Color color; color.SetFractionalRGB(r, g, b);
unsigned int abgr = (unsigned int)color; rc = (int) ABGR_to_ARGB(abgr); **/ var c0 = new Rhino.Display.Color4f(p0); var c1 = new Rhino.Display.Color4f(p1); var c2 = new Rhino.Display.Color4f(p2); float s0 = (float) t0; float s1 = (float) t1; float s2 = (float) t2;
float R = s0 * c0.R + s1 * c1.R + s2 * c2.R; float G = s0 * c0.G + s1 * c1.G + s2 * c2.G; float B = s0 * c0.B + s1 * c1.B + s2 * c2.B; color = new Rhino.Display.Color4f(R, G, B, 1); } } return color.AsSystemColor(); }
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ort and export from the images below and also from the HELP file of DB in attachments (Page 71: Importing Geometric Data; Page 78-80: Import 3 - D CAD Data). In their HELP file, they mention about "import geometric data".
However, regarding the input of schedules, loads, constructions and etc., DB normally uses "Component " and "Template" (Page 29: Templates And Components; Page 591: Templates; Page 533: Components). "Templates" are databases of typical generic data, including Activity templates, Construction templates, Glazing templates, Facade templates, HVAC templates, Location Templates, and etc. "Component " are databases of individual data items (e.g. a construction type, material, window pane).
Both "Component " and "Template" are allowed to be imported and exported by using "Import / Export library data" command (.ddf format - DB Database File; Page 734: Import Components/Templates, Export Components/Templates). DB also allows us to build up our own libraries of templates and components (Page 731: Library Management; Page 733: Template Library Management).
In order to import both geometric information and other information related to schedules, loads, constructions and etc. from GH to BD, we supposed the following two ways:
1. GH(HB+GB) --> gbXML (both geometric and "Component " and "Template" information) --> DB
This is the way we most prefer. We did see information related to schedules, loads, constructions encoded in the gbXML file generated by GB, but still do not know the reason why DB did not take this information (I also mentioned this in Q6 within the gh file). We assume this might because the gbXML file we create encodes the schedules based on a different template / schema than the one DB expects. We also post this question to the DB forum for help.
(http://www.designbuilder.co.uk/component/option,com_forum/Itemid,25/page,viewtopic/p,13755/#13755)
2. GH(HB+GB) --> gbXML (geometric information only) + .ddf ("Component " and "Template" information only) --> DB
If the first way doesn't work and DB only takes geometric information from the gbXML, then we might think of the other way - generating the .ddf files from GH(HB+GB) to pass the schedule, load and construction information to DB.
I was wondering if it is feasible for HB and GB to have this function? And what is your suggestion to achieve this?
In addition, we notice that DB can export XML files (not gbXML), so we are trying to figure out if DB also accepts / reads the XML file. If so, we might be able to convert the gbXML (with both geometric and schedule information) to XML. What do you think about that?
Thank you again for all your help!
Best,
Ding
DB import
DB export
Template libraries
Component libraries
…
y using the Honeybee_Update Honeybee component.
The video below (best viewed in full-screen mode) provides an idea of what these components are capable of being used for:
The video below shows how these components can be used in an existing Honeybee project (for additional links please open this video in youtube):
I have uploaded two examples as Hydra files that show how these components can be used for grid-point and image-based simulations:
Example1 : Grid Point Calculations
Example2: Image based simulation
Finally, a more esoteric application is demonstrated in this video:
These components are still in the beta-testing stage. Some of the limitations of the components are:
1. Only Type C photometry IES files are supported at present.
2. Rhino is likely to get sluggish if there are too many luminaires (i.e. light fixtures) present in a scene.
3. Due to the spectral limitations of the ray-tracing software (RADIANCE), simulations involving color mixing might not be physically realizable.
Additional details about photometric and spectral calculations are probably an overkill for this forum. However, I'd be glad to answer any related questions. Please report any bugs or request new features either on this forum or on Github.
Mostapha, Leland Curtis, Reinhardt Swart and Dr. Richard Mistrick provided valuable inputs during the development of these components.
Thanks,
Sarith
Update 16th January 2017:
An example with some new components and bug fixes since the initial release announcement can be found here
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te some cut sheets, but not to optmize material, rather define some cut lines. Everything that I am cutting is made of planar wood elements, but there are very specific geometries (mostly straight lines) and I have to put tolerances and radiasas at the corners in order to cut on the cnc mill. Spending time to figure out how to automate is necessary, but I am stuck!
One thing the definition is doing is taking my brep modeled components in rhino and makking them into 2d close curves and laying them side by side. It works...not ideal as its not layed out in a sheet, but that is not the most important part.
Another particular problem is that you will see some notches in the curves, which other pieces will slip into, so different slots need different specific offsets (making them larger) as a toelrance to allow for material play. This I don't even know how to set up so maybe it will just have to wait.
THE MAIN QUESTION, and super important would be, LIFESAVER:
At all 'inward' corners...which I think will always mean concave corners (most are 90 degrees, but are within to sides, instead of a corner sticking out). I'm sure its obviousy, but the reason being the outward corners a circular dril bit can cut, but inward ones need an arc profile extended beyond where the corner of the other piece will fit into. The drill bit i am using is 6mm, so 6mm diamters arcs is what i'm working with.
I have managed to put such an arc at every vertices of each cut piece. The problem being some stick outward isntead of cutting into the piece. So each one needs to be orieneted correctly. Ideally they would also only draw into inward corners, but I can always delete them out. I think maybe I am missing a more logical mathematical way of defining?
For these geometries it is not very important which side the half circle arc in on in the inward corners, but I also have some geometries that I will have to control where the circles face according to the rest of the cut piece.
The cutouts in the middle of the pieces that are curves do not need such corners obviously.
The picture is an example drawn
I hope this isn't too specific and long. in general though automating fabrication, and controling pracitcal math and orientation problems like this is itnersting to me!
THANKS…
perienced with grasshopper, but so far I've managed to combine the following:
Giulio Piacentino's "Catenary arch from height" script
Pirouz Nourian's "Mobius" script (Obtained from a friend)
End Result:
Here's where I'm stuck: I want the mobius twist to revolve around the midpoint of the arch, but the script uses the input values to determine the endpoints, resulting in a weird sinuous shape when viewed from above. Also, the secondary end points (generated by the mobius script, determining the width of the surface) are generated by default along the z axis, resulting in an arch that only touches the "ground" at two points. I attempted to work around this issue by trying to force the zHeight parameter to correspond with the y axis (thus rotating the arch 90 degrees so it would lay "flat"), but the script interprets the third point as a value and not as an actual point to bisect. I thought this might be an issue with the C# component that I obtained from Giulio Piacentino's script, so I attempted to tinker around with the source code. Unfortunately, I'm not fluent in C# so I only managed to mess everything up (I've since recovered the code from the cache). Anybody got some ideas? -BC …
onsidered period.
Even if the end of July for the mediterranean climate is not the best period to perform an adaptive comfort analysis (it's just a pretest to define a LB model) I want to refine the Adaptive comfort Chart (AC) by changing the external air temperature data imported from the .epw file with that of monitored data as reported here below:
Where the monitored ext air temperature are in this form (green panel below):
I have used the comfortPar component to set the following parameters:
Adaptive chart as defined by EN 15251
90% of occupants comfortable
the prevailing outdoor temperature from a weighted running mean of the last week
fully conditioned space (even if it is not properly in line with AC as already discussed)
The question is this: the AC component could correctly apply the code below if there is only a list of external temperature data for a restricted period (without indication about the limits of this period) and not for an entire year?
else: #Calculate a running mean temperature. alpha = 0.8 divisor = 1 + alpha + math.pow(alpha,2) + math.pow(alpha,3) + math.pow(alpha,4) + math.pow(alpha,5) dividend = (sum(_prevailingOutdoorTemp[-24:-1] + [_prevailingOutdoorTemp[-1]])/24) + (alpha*(sum(_prevailingOutdoorTemp[-48:-24])/24)) + (math.pow(alpha,2)*(sum(_prevailingOutdoorTemp[-72:-48])/24)) + (math.pow(alpha,3)*(sum(_prevailingOutdoorTemp[-96:-72])/24)) + (math.pow(alpha,4)*(sum(_prevailingOutdoorTemp[-120:-96])/24)) + (math.pow(alpha,5)*(sum(_prevailingOutdoorTemp[-144:-120])/24)) startingTemp = dividend/divisor if startingTemp < 10: coldTimes.append(0) outdoorTemp = _prevailingOutdoorTemp[7:] startingMean = sum(outdoorTemp[:24])/24 dailyRunMeans = [startingTemp] dailyMeans = [startingMean] prevailTemp.extend(duplicateData([startingTemp], 24)) startHour = 24
…
ting at multiple geometries in the same location. I simply sorted the list of values and used the Delete Consecutive component. This potentially rearranges the order of values but I don't think that matters in your case. I also threw in an Int component which actually seems to make a difference (try sidestepping it and you will see!).
2-I flattened the output of the mesh component before sending it to union. This ensures that the original mesh is booleaned once with all the components rather than individually with each of the 86 components.
Is this what the result should look like?
One suggestion for future postings: when referencing geometry in rhino, it often helps if you attach your rhino file as well so people don't have to guess where you are starting from.
If you have further questions, just ask ;-)
cbass…