I have a graph with vertices and edges (orthogonalEdgeStyle) and want to create new edges. After the creation the routing most times crosses existing vertices. Is there any possibility to route the new edges in a way that they not cross any vertex?
The best solution would be that other edges are also not crossed, but I think this is even more complex.
Any help is appreciated, if there is no build-in functionality (I found nothing), perhaps anybody has an idea where to start (overwrite function, algorithm)?
I'm also searching for a possibility to automatically create "bridges" if two edges are crossing.
Related
Theres 2 parts to my problem and they are related. I have a weird shape on my interface illustrated below, I am trying to randomly spawn MovieClips within its' boundaries but I am having some trouble finding a good way to do it.
Question 1: I can run an If condition to check with bitMapData.hitTest to see if the MovieClip has randomly spawn within this shape, if it doesn't simply retry with a new set of random coordinates. However, is there a better way? Like a way to only take into account coordinates within the shape? There will be plenty of MC spawned at one go so I am hoping to lessen the load, or at least find an efficient way to do this calculation.
Question 2: The MovieClips spawned within this shape will eventually have collision detection mechanics that will repel itself when interacted with. Is there a way to contain them within this shape via some kind of boundary detection?
If it was a square, we could easily have contained them with a quick check on all 4 edges, but not with this shape. Currently I am thinking of using bitMapData.hitTest again to detect for out-of-bounds after being repelled, but how do I know which Point() is the nearest 'edge' of this shape to return the MC to?
For question 1: I'm going to go on an assumption that you have some geometry data about the shape.
One method you can use to check if a point is within a shape is to take that point, then draw a line from that point to infinity (the edge of the screen) in one direction. Then count how many times that line intersects an edge of the shape. If it's odd, the point is within the shape (or on the edge) and if it's even, than that point is outside of the shape.
First link in google: https://www.geeksforgeeks.org/how-to-check-if-a-given-point-lies-inside-a-polygon/
Or can also try a more simple method (at the cost of doing more work): if the above shape is generated with all squares and rectangles and you know the point and size of all of those: can just do a check for the point vs all the squares and rectangles that make up the shape.
For question 2: As Organis mentioned, I'd go with a library like Box2D to do this. You'll most likely spend tons of time (that you may not want to) if you try to implement this alone.
The big issue is how much cpu or gpu the code uses. You're trying to avoid using any collision detection. Collision detection is having code do calculations to determine the edges of an object. It should be the last option.
Most of the time you know there's no need for collision detection. You know where everything is and how big it is. Everything has a centerpoint and comparing simple number coordinates is the lightweight way to check if there's a need to check further.
When things get near each other, you only need to do a collision detection on the immediate area around an object. See how your shape fits in a box that is easy to check for collisions? That box should get a collision check before the actual jagged shape inside it.
Yes that collision detection box has to be drawn or mapped but it's done when the object is defined, not when the game is playing. If you are using sprite sheets, keep an xml of the boxes or circles around the shapes.
I have read several of the posts concerning Polygonal Search, but they are all about fixing or updating the programs. I am just wondering how it works. If there is a way I can get something like pseudo code of it or an explanation of how a shape captures the data points.
To further specify my goal, I am trying to make a constant square that will be held over a map (such as google maps), but the map can move around behind the square, however, the square will continue to report whatever cities lie within its bounds. [I will eventually proceed to building it, I just need some guidance]
Thank you.
There is an open-source library which has a function to check if two shapes overlap. You can check source code:
http://turfjs.org/static/docs/module-turf_inside.html
If you look for theory behind it check Hyperplane separation theorem
Hi I have a box2d compound body which is intended to be a vehicle seen in profile. when it goes backwards i'd like it to face the other way ie flip/reflect on the x axis. is there an easy way to so this? I find nothing in google though much false hits due to other uses of word reflection.
I could recreate the body but I'd have to do the whole out-of-time delete/add thing? and it seems a bit cumbersome. i tried body.getFixtureList and setting the vertices but tyhe method is flagged don't change the list. does that mean don't add remove? or don't edit? Anyways nothing changes on screen. Off to double-check my code...
Am I missing something?
Changing the vertices won't work. Only possibility to do that is to recreate the body as you said. And don't think that it will be slow just because you will have to delete it and then create it again. Box2d could probably create 100 of your vehicles in one frame without having too much of a struggle.
And for the whole flipping process you would scale your vertices x component by -1. And if your vertices origin wasn't in center of shape you would have to adjust the x coordinate of the whole vehicle (or just have the origin properly placed in the first place).
Also when recreating the body you would probably want to save the linear and angular velocity of your original body. And then once you create the new one apply those velocities to the new body. If you don't do that you would make your vehicle freeze once you do the flip.
Ok, so I'll try to be as descriptive as possible.
I'm working on a project for a client that requires a jibjab-style masking feature of an uploaded image.
I would like to be able to generate a database-storable object that contains anchor/control positions of a bezier shape, so I can pull it out later and re-mask the object. This all is pretty easy to do, except for one catch : I need to create the bezier object from a user-drawn outline.
So far, here's how I imagine the process going:
on mouse down, create a new sprite, beginFill, and moveTo mouse position.
on mouse move, lineTo an XY coordinate.
on mouse up, endFill.
This all works just great. I could just store the info here, but I would be looking at a GIGANTIC object full of tons of pretty useless x/y coordinates, and no way to really make fine-tuning changes outside of putting handles on every pixel. (I may as well give the end user a pencil tool...)
Here's what I'm thinking as far as bezier curve calculation goes :
1: Figure out when I need to start a new curve, and track the xy of the pixel on this interval. I'm imagining this being just a pixel count, maybe just increment a count variable per mouse move and make a new one every x pixels. The issue here is some curves would be inaccurate, and others unnecessary, but I really just need a general area, not an exact representation, so it could work. I'd be happier with something a little smarter though.
2: take each new x/y, store it as an anchor, and figure out where a control would go to make the line curve between this and the last anchor. this is where I get really hung up. I'm sure someone has done this in flash, but no amount of googling can seem to help me out with the way to get this done. I've done a lot of sketching and what little math I can wrap my brain around, but can't seem to figure out a way of converting pixels to beziers.
Is this possible? All I really need is something that will get close to the same shape. I'm thinking about maybe only placing anchors when the angle of the next pixel is beyond 180 degrees in relation to the current line or something, and just grabbing the edge of the arc between these changes, but no matter how hard I try, I can't seem to figure out how to get this working!
Thanks for your help, I'll be sure to post my progress here as I go, I think this could be really useful in many applications, as long as it's actually feasible...
Jesse
It sounds like a lot of work to turn pixels into Bezier curves. You could try using something like the Linear least squares algorithm. http://en.wikipedia.org/wiki/Linear_least_squares
A different tact, could you have your users draw vector graphics instead? That way you can just store the shapes in the database.
Another cool method of converting raster to vector would be something like this iterative program: http://rogeralsing.com/2008/12/07/genetic-programming-evolution-of-mona-lisa/
Good luck
In my answer to this question I discuss using autotrace to convert bitmaps to beziers. I recommend passing your user drawing through this program on the server. Autotrace does a fantastic job of tracing and simplifying so there is no need to try and reinvent the wheel here.
Thanks for the answers, although I guess I probably should be more specific about the application, I'm really only needing an outline for a mask, so converting images to vectors or polygons, despite how cool that is, doesn't really fix my issue. The linear least squares algorithm is mega cool, I think this might be closer to what I'm looking for.
I have a basic workaround going right now, I'm just counting mouse moves, then every X (playing with it to get most desirable curve) moves, I grab the xy position. then, I take every other stored xy, and turn it into an anchor, the remaining xys are turned into controls. This is producing somewhat desirable results, but has some minor issues, in that the speed at which the mask is drawn effects the number of handles, and it's really just getting a general area, not a precise fit.
Interestingly, users seem to draw slower for more precise shapes, so this solution works a lot better than I had imagined, but it's not as nice as it could be. This will work for the client, so although there's no reason to pursue it further, I like learning new things, and will spend some off the clock time looking into linear least equations and seeing if I can drum up a class that will do these computations for me. If anyone runs across some AS3 code for this type of thing, or would like some of mine, let me know, this is an interesting puzzle.
I have a similar problem to this post. I need to display up to 1000 polygons on an embedded Google map. The polygons are in a SQL database, and I can render each one as a single KML file on the fly using a custom HttpHandler (in ASP.NET), like this http://alpha.foresttransparency.org/concession.1.kml .
Even on my (very fast) development machine, it takes a while to load up even a couple dozen shapes. So two questions, really:
What would be a good strategy for rendering these as markers instead of overlays once I'm beyond a certain zoom level?
Is there a publicly available algorithm for simplifying a polygon (reducing the number of points) so that I'm not showing more points than make sense at a certain zoom level?
For your second question: you need the Douglas-Peucker Generalization Algorithm
For your first question, could you calculate the area of a particular polygon, and relate each zoom level to a particular minimum area, so as you zoom in or out polygon's disappear and markers appear depending on the zoom level.
For the second question, I'd use Mark Bessey's suggestion.
I don't know much aobut KML, but I think the usual solution to question #2 involves iterating over the points, and deleting any line segments under a certain size. This will cause some "unfortunate" effects in some cases, but it's relatively fast and easy to do.
I would recommend 2 things:
- Calculate and combine polygons that are touching. This involves a LOT of processing and hard math, but I've done it so I know it's possible.
- Create your own overlay instead of using KML in PNG format, while you combine them in the previous suggestion. You'll have to create a LOT of PNGs but it is blazing fast on the client.
Good luck :)
I needed a solution to your #2 question a little bit ago and after looking at a few of the available line-simplification algorithms, I created my own.
The process is simple and it seems to work well, though it can be a bit slow if you don't implement it correctly:
P[0..n] is your array of points
Let T[n] be defined as the triangle formed by points P[n-1], P[n], P[n+1]
Max is the number of points you are trying to reduce this line to.
Calculate the area of every possible triangle T[1..n-1] in the set.
Choose the triangle T[i] with the smallest area
Remove the point P[i] to essentially flatten the triangle
Recalculate the area of the affected triangles T[n-1], T[n+1]
Go To Step #2 if the number of points > Max