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Hello!
A lot of math here: I have 4 points and I want to have a "soft-curved" function approximating them best, without going too far from the track. I used a polynom like a*x^3 + b*x^2 + .... and used CAS to calculate algebraic solutions for values of a,b,c,d from the point coordinates.
It works, but the curve I get, while going through the points, takes long curves away, here an example:
Anyone knows a better solution?
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How about B splines?
edit: ok bad idea, that wouldn't go through the points
edit2: simple cubic splines perhaps?
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B-Splines seem to be the right keyword. As i see in wiki, they should go exactly through knots, which would be what i need. I'll checkout soon. Do you maybe have a ready-to-use implementation in VB.NET?
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I don't, but it probably exists. However, B-splines don't normally go through the knots..
Cubic Hermite splines[^] however, do. But they miss the outer points, so you'd have to extrapolate 2 extra points.
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Yeah, that's the easy way to do it.
I'm using Catmull-Rom splines (very similar to Hermite) in a little app I'm writing just now. I simply add 2 "invisible" points, one at either end of the curve, and move them with the visible end points as the user edits the curve shape.
Works a treat 
There are three kinds of people in the world - those who can count and those who can't...
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Reduce the order of the polynomial and use least squares?
You measure democracy by the freedom it gives its dissidents, not the freedom it gives its assimilated conformists.I'm a proud denizen of the Real Soapbox[ ^] ACCEPT NO SUBSTITUTES!!!
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Is anyone aware of any existing work to find the centerline of a font boundary?
How about a suggested method?
For example the letter V would actually just be 2 lines instead of 7.
I have tried exploding the glyph boundary into lines and then creating perpendicular lines from the mid points. Then I trim to near intersect points. Results are not great.
Thanks,
Jason
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I've sometimes wondered this very thing myself, and done some experiments, but unfortunately the shape I suspect you're after isn't really well defined.
One approach I used to generate a bitmap of the "skeleton" was to draw text repeatedly using increasing stroke widths, adding to the skeleton any island of pixels which disappeared from one iteration to the next. This was slow, but it somewhat worked; the results were used to generate an HPGL file for an engraving machine (the goal was to engrave the entire interiors of letters, but I wanted the engraver to follow the contours of the letters so the tooling marks would look good).
One slight caveat is that for decent results it's necessary to draw the fonts using miter joins, but some fonts have acute angles which look very bad (the joins either stick out way too far, or else they're converted to bevel joins which are way too short). This can be fixed somewhat by adding a very short extra stroke to acute joins, perpendicular to the bisector of the two lines being joined. This will generate a bevel whose distance from the intersection will be half the stroke width.
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Hey all,
I have written a designer (similar to class designer) in WPF and am looking to build a diagram layout algorithm such as orthogonal routing algorithm. However I was wondering if there is an open implementation available that one can use. In any ways are there any obvious algorithms that you guys can think of (I can imagine a variation of dijkstra's shortest path algorithm).
Thanks in advance,
Ashish
Ashish Kaila
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I don't understand why Dijkstra's alogorith is restricted only to positive costs . It does seem to do a good job no matter what .. Can anyone tell me why do we have that restriction or give me an example that fails with negative costs ?
Thank you !
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Well… I visit your website first time and found this site very useful and interesting! Well… you guys doing nice work and I just want to say that keep rocking and keep it up!!!!
Mark Alter
interview questions
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..pay for it, you must. I voted for a "remove"
I are troll
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Well, this might sound as a weird algorithm discussion, it's a theoretical one, although I wouldn't mind seeing the abstract implementation. Here it is.
In a 2D game, you have a player and enemies in 2D space. A player has ranged attack as PlayerRange and enemies have their own range(s), but let's say they all have the same range of EnemyRange. What I'm interested in is how to separate a cloud of enemies into groups and circle them to death. here is my solution:
First, acquire range between enemies that will be considered as min-max range to be between each other in a group, and separate cloud of enemies into sub-clouds. Once this is done, create convex hull for each of sub-groups and determine closest sub-group player is to. If player is inside any of those, find closest line of the convex hull and follow in direction of normal to it until player is outside the sub-group.
While outside, construct expanded convex hull using PlayerRange and follow it from point to point until convex hull is no more (i.e. has only 2 enemies left). Once it is so, use simple sphere as path to follow around them until they are destroyed.
Now, all this assumes that sub-group and convex hull calculations are done on a per-frame basis, because enemies do move on their own and may merge from one sub-group to another. This raises a question as to which next point to go to. I think a good solution for this would be to choose next counter- or clockwise point around convex hull and go towards it.
What do you think, is this a good way of doing "circling to death" or are there others?
"Do not try. Do"
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Your question isn't very clear, but it appears you want some way to group enemies into clouds to surround them.
One approach is Cluster Analysis. Start with a list of all enemies and a table of the distances among them. Group the two closest enemies into a cluster. The cluster becomes a new "enemy" with a centroid (average X and Y coordinates). Continue grouping enemies until the closest are above some threshold. The clusters of enemies remaining are your compact clouds.
If you have many enemies to group, a KD-tree (http://en.wikipedia.org/wiki/Kd-tree[^]) is efficient for finding nearest neighbors.
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IN: vector<POINT>--the complex area Point
OUT:vector<vector<POINT>>--the boundarey of the area,including the out boundary and inside boundary.
bool ConvertInnerToBorder(vector<vector<POINT>>;vector<POINT>)
{
}
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how to scan or know a file was copied to HDD after scaning files over that path file in HDD? i saw this Algorithms in some viruse protection program. how do they do? what Algorithms do they use ?
modified on Friday, May 29, 2009 7:00 AM
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They're not using .NET - seems that Avast! has hooked the FindFiles function. I found the process reading files whenever I opened a virtual DOKAN drive.
What you need is someone who is very familiar with the WinAPI
I are troll
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can u give some link page for about what u said ?
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And people supplying the news through Twitter and mobile phones is going to help make it better how? That's too bad. I would like to know what they're talking about though.
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