I am working on project where i need to find a path to the nearest (of many) goal node in 2D grid (8 connections in any node: N,S,W,E,NW,NE,SW,SE). There can be walls blocking path on the way. There is no problem when it comes to find path to one goal node, but how could i find in reasonable time which goal is nearest? I don't think running A* for every goal node and getting length of every path found to compare is reasonable way, how else can it be done?
Is A* somehow capable of finding path to nearest node, or the nearest goal must be found other way and then passed to A* as only goal?
Legend:
White - walkable
Grey - walls
Blue - myself
Green - goals
Red - enemy (i am planing to keep distance from enemy at X SQM)
Yes, just set EstimatedDistanceToEnd (aka. h(x)) to the minimum estimate over all end-nodes. Then just stop the search when you hit an end-node.
A* is for informed searches where we have some data other than just goal state... According to your question it seems like there is no relevant data and we just know what our goal state is. If that is the case then you can simply apply BFS.
Related
I am using influxdb together with grafana to track temperatures in my house. I am also tracking some switches. One of the switches is connected to a heater, I want to see how the temperature outside relates to how often/long the heater is running. The heater just publishes a value of 0/1 for on/off so it is a little difficult to see the relationship in one graph.
I want to know if there is a way to have a filled-in background behind the temperature graph whenever the heater switch is on. Something similar to the time region feature of grafana, only with values from another source not time. A workaround (which I want to avoid), to better illustrate what I want, would be to have the value of 1 replaced by 200 and limit the graph to only display up to a more sane number. The result would be that the higher number of 200 is "off the charts" and I would see the fill of that graph.
Here is an image of the time region graph which is similar to how I picture what I am looking to do.
You can achieve the effect of background color by assigning the heater switch value to right y axis in the Visualization tab, setting axis limits to 0 and 1 and filling the area below the line with a solid color.
I am trying to make a new tool for the tabletop simulator community based on my "pack up bag". The Packup Bag is a tool that remembers world position and rotation of objects you place inside it, so you can then place them back in the same positions and rotations they came from when "unpacking the bag".
I have been trying to modify this so it spits things out in a relative position and rotation to the bag, instead of using hardcoded world coordinates. The idea here is that players can sit at any location at the table, pick the faction bag they wish to play.. drop it on a known spot marked for them and press the place and it will populate contents of the bag relative to its location.
Now I have gotten some of this worked out... I am able to get the bag to place relative in some ways .. but I am finding it beyond my maths skills to work out the modifications of the transforms.
Basically I have this part working..
The mod understands relative position to the bag
The mod understands relative rotation to the bag
BUT.. the mod dose not understand relative position AND rotation at the same time.... I need someway to modify the position data relative to the rotational data... but can not work out how.
See this video....
https://screencast-o-matic.com/watch/cFiOeYFsyi
As you can see as I move the bag around the object is placed relative to it.... but if I rotate the bag, the object has the correct rotation but I need math to work out the correct position IF it is rotated. You can see it is just getting placed in the same position it was as if there was no rotation... as I haven't worked out how to code it to do this.
Now I have heard of something called "matrix math" but I couldn't understand it. I'm a self taught programmer of only a few months after I started modding TTS.
You can kinda understand what I mean I hope.. In the video example, when I rotate the bag, the object should be placed with the correct rotation but the world position needs to be changed.
See this Example to see relative rotation ....
https://screencast-o-matic.com/watch/cFiOeZFsyq
My code dose this by remembering the self.getPostion() of the bag and the obj.Position() of the object getting packed up.. it then dose a self - obj and stores that value for the X and Y position. It also remembers if it is negative or position and then when placing it uses the self.postion() and adds or subtracts the adjustment value. Same for rotation.
Still I do not know what ot go from here.. I have been kinda hurting my head on this and thought maybe some of you math guys might have a better idea on how to do this.
: TL;DR :
So I have
bag.getPosition() and obj.getRotation()
bag.getRotation(0 and obj.getRotation()
These return (x,y,z}
What math can I use to find the relative position and rotation of the objects to the bag so if I rotate the bag. The objects come out of it in a relative way...
Preferably in LUA.. thank you!
I'd hope you've found the answer by now, but for anyone else finding this page:
The problem is much simpler than what you're suggesting - it's basic right triangle trigonometry.
Refer to this diagram. You have a right triangle with points A, B, and C, where C is the right angle. (For brevity, I'll use abbreviations opp, adj, and hyp.) The bag is at point A, you want the object at point B. You have the angle and distance (angle A and the length of the hyp, respectively), but you need the x,y coordinates of point B relative to point A.
The x coord is the length of adj, and y coord is the length of opp. As shown, the formulas to calculate these are:
cos(angle A) = adj/hyp
sin(angle A) = opp/hyp
solving for the unknowns:
adj = hyp * cos(angle A)
opp = hyp * sin(angle A)
For your specific use, and taking into account the shift in coordinate system x,y,z => x,z,y:
obj_x_offset = distance * math.cos(bag.getRotation().y)
obj_z_offset = distance * math.sin(bag.getRotation().y)
obj_x_position = bag.getPosition().x + obj_x_offset
obj_z_position = bag.getPosition().z + obj_z_offset
Diagram source:
https://www.khanacademy.org/math/geometry/hs-geo-trig/hs-geo-modeling-with-right-triangles/a/right-triangle-trigonometry-review
I have some experience with Metal and quite a bit with Unity and am familiar with setting up meshes, buffers, and the backing data for drawing; but not so much the math/shader side. What I'm struggling with is how to get an endless scrolling world. So if I pan far to the right side I can see the left side and keep going.
The application of this would be a seamless terrain that a player could scroll in any direction forever and have it just wrap.
I don't want to duplicate everything on draw and offset it, that seems horrendously inefficient. I am hoping for a way to either use some magic matrix math or some sort of shader to get things wrapping/drawing where they should when panning the map. I've searched all over for some sort of guide or explanation of how to get this working but haven't come up with anything.
I know a lot of old (dos) games did this somehow, is it still possible? Is there a reason why it seems the industry has migrated away from this type of scrolling (bounding to edges vs wrapping)?
I have created a simple example demonstrating what you're looking for (I think).
The basic idea of it is that you draw the map in a repeating grid, using the drawPrimitives(type:vertexStart:vertexCount:instanceCount:) method on MTLRenderCommandEncoder. As the instance count you want to pass in the number of identical maps you want to draw, extending it as far as needed to not see where it ends. In my example I used a simple 5x5 grid.
To not have the user see the edge of the map, we're gonna calculate their position modulo 1 (or whatever size your map is):
func didDrag(dx: CGFloat, dy: CGFloat) {
// Move user position on drag, adding 1 to not get below 0
x += Float(dx) * draggingSpeed + 1
z += Float(dy) * draggingSpeed + 1
x.formTruncatingRemainder(dividingBy: 1)
z.formTruncatingRemainder(dividingBy: 1)
}
This is how it looks:
Just a follow up on what I have actually implemented. First I essentially have an array of x,y points with altitude, terrain type and all that jazz. Using some simple % and additions/subtractions it is trivial to get the nodes around a point to generate triangles
On a draw I calculate the first showing point and the last showing point and calculate the groups of triangles shown between those points. The first/last point take into account wrapping, it is then pretty trivial to have an endless wrapping world. For each group a translation offset is passed via a uniform matrix for that group which will position that section where it should belong.
I set it via renderEncoder.setVertexBytes(&uniform, length:..., offset:...)
Has anyone been able to do spatial operations with #ApacheSpark? e.g. intersection of two sets that contain line segments?
I would like to intersect two sets of lines.
Here is a 1-dimensional example:
The two sets are:
A = {(1,4), (5,9), (10,17),(18,20)}
B = {(2,5), (6,9), (10,15),(16,20)}
The result intersection would be:
intersection(A,B) = {(1,1), (2,4), (5,5), (6,9), (10,15), (16,17), (18,20)}
A few more details:
- sets have ~3 million items
- the lines in a set cover the entire range
Thanks.
One approach to parallelize this would be to create a grid of some size, and group line segments by the grids they belong to.
So for a grid with sizes n, you could flatMap pairs of coordinates (segments of line segments), to create (gridId, ( (x,y), (x,y) )) key-value pairs.
The segment (1,3), (5,9) would be mapped to ( (1,1), ((1,3),(5,9) ) for a grid size 10 - that line segment only exists in grid "slot" 1,1 (the grid from 0-10,0-10). If you chose a smaller grid size, the line segment would be flatmapped to multiple key-value pairs, one for each grid-slot it belongs to.
Having done that, you can groupByKey, and for each group, calculation intersections as normal.
It wouldn't exactly be the most efficient way of doing things, especially if you've got long line segments spanning multiple grid "slots", but it's a simple way of splitting the problem into subproblems that'll fit in memory.
You could solve this with a full cartesian join of the two RDDs, but this would become incredibly slow at large scale. If your problem is smallish, sure, this is an easy and cheap approach. Just emit the overlap, if any, between every pair in the join.
To do better, I imagine that you can solve this by sorting the sets by start point, and then walking through both at the same time, matching one's current interval versus another and emitting overlaps. Details left to the reader.
You can almost solve this by first mapping each tuple (x,y) in A to something like ((x,y),'A') or something, and the same for B, and then taking the union and sortBy the x values. Then you can mapPartitions to encounter a stream of labeled segments and implement your algorithm.
This doesn't quite work though since you would miss overlaps between values at the ends of partitions. I can't think of a good simple way to take care of that off the top of my head.
I have a little logical problem over here.
As the title says, I try to build a boardgame as a computer-program (maybe with internet-support, but thats another story)
As for now, I have a map, which has some crossroads in it, hence I cannot simply define the fields as '1, 2, 3, 4, ...' because if there is a crossroad at field 10, I would have more than one field which has to be labeled 11 (Because then there is a field left and right of field 10, for example.)
So the problem is, if I cannot define the Board in numbers then I cannot simply get the possible positions a player can take when he rolls 2d6-dices with calculating 'Field-Nr. + RandomRange(1,6) + RandomRange(1,6)'
Does anybody have an idea, how to define a Map like this on another way, where I still can calculate the possible new-fields for Player X with a 2d6-dice-roll?
Thanks in advance.
If i understand well... (i don't thing so) this might help you. Just use dynamic arrays for your boardgame field and change your actions after the dimensions x,y .... Look at this "type Name = array of {array of ...} Base type; // Dynamic array"
It sounds like you have a graph of connected vertices. When a player is at a particular vertex of N edges, assuming N < 12, the new Field will be reached from traversing edge number N % ( rand(6) + rand(6) ).
You could also just do rand(12), but that would have an even distribution, unlike 2d6.
Instead of dynamic arrays, I would recommend using a linked-list of records to describe the surrounding cells, and traverse the player's location and possible moves using that linked-list.
First, define a record that describes each cell in your board's playable grid (the cells on the grid can be four-sided like a chessboard, or hexagonal like in Civilization V) ... each cell record should contain info such as coordinates, which players are also in that cell, any rewards/hazards/etc that would affect gameplay, etc. (you get the idea).
Finally, the linked-list joins all of these cells, effectively pointing to any connected cells. That way, all you'd need is the cell location of Player X and calculate possible moves over n amount of cells (determined by the dice roll), traversing the adjoining cells (that don't have hazards, for example).
If all you want is to track the possible roads, you can also use this approach to identify possible paths (instead of cells) Player X can travel on.