I am working on a drawing program and am trying to figure out the best way to imitate the 'magnet' behavior found in applications such as Omnigraffle. The idea is: as a line is drawn between two objects (visual objects on screen, not OOP objects), as the line from the first object approaches the second, a 'magnet' or 'node' on the second will highlight or the second object will highlight.
I was looking to keep all of the on-screen objects in an array and using notifications to send that array the position of the end of the line as it moves. This way, I could have each object do its own comparison and say "Hey, I have a node near the line, I think I'll light it up".
I was also wondering if it would be the same approach if I wanted to have two objects, say boxes for instance, that would snap together, side by side, when they came into proximity with each other. This way, it would be possible to line up the boxes on the same X or Y coordinate
I'm not concerned about the highlighting or having the line snap to the position of a node, I'm just wondering about the best way to implement the 'edge proximity detection' part of this problem.
If you are using CGRect types I'd suggest you use the two functions CGRectInset() and CGRectIntersectsRect()
Use CGRectInset() to expand one or both rects and then use CGRectIntersectsRect() to see if you have a match. You could also use (at the same time) CGRectIntersectsRect() on the original rects to see that you only have are close and not covering each other.
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I have 3d elements (triggers) that spawn content boxes when clicking on them. I am searching for an algorithm that spawns elements in an empty area close to the trigger. A 2d approach might be enough since the content boxes need to face the user.
The spawned content box should neither overlap the trigger object, nor other 3d elements / contentboxes.
Example:
If the trigger is a long vertical tube, the first contentbox might spawn to the left of it, the next one would spawn to the right since the left is already occupied with contentbox 1. The third contentbox might then spawn above/below the first contentbox or if there is other stuff in the way then to the left of the first contentbox.
This should work in realtime, it doesnt have to be the actual closest point but should aim for keeping everything closely together. I assume that this is a problem many people solved before me but somehow I couldnt find sufficient information, maybe I am lacking the correct search terms, I am happy to hear about different approaches, hints & ideas..
Thanks
friday
Try to create a grid on the existed points in the plane or space. This grid could be two perpendicular line on each existed point. After that, create a tree to search on this space. Or just create a kd-tree on these points. Youcan find more about these in computational geometry context.
Hy!
I am working with huge vertice objects, I am able to show lots of modells, because I have split them into smaller parts(Under 65K vertices). Also I am using three js cameras. I want to increase the performance by using a priority queue, and when the user moving the camera show only the top 10, then when the moving stop show the rest. This part is not that hard, but I dont want to put modells to render, when they are behind another object, maybe send out some Rays from the view of the camera(checking the bounding box hit) and according hit list i can build the prior queue.
What do you think?
Also how can I detect if I can load the next modell or not.(on the fly)
Option A: Occlusion culling, you will need to find a library for this.
Option B: Use a AABB Plane test with camera Frustum planes and object bounding box, this will tell you if an object is in cameras field of view. (not necessarily visible behind object, as such a operation is impossible, this mostly likely already done to a degree with webgl)
Implementation:
Google it, three js probably supports this
Option C: Use a max object render Limit, prioritized based on distance from camera and size of object. Eg Calculate which objects are visible(Option B), then prioritize the closest and biggest ones and disable the rest.
pseudo-code:
if(object is in frustum ){
var priority = (bounding.max - bounding.min) / distanceToCamera
}
Make sure your shaders are only doing one pass. As that will double the calculation time(roughly depending on situation)
Option D: raycast to eight corners of bounding box if they all fail don't render
the object. This is pretty accurate but by no means perfect.
Option A will be the best for sure, Using Option C is great if you don't care that small objects far away don't get rendered. Option D works well with objects that have a lot of verts, you may want to raycast more points of the object depending on the situation. Option B probably won't be useful for your scenario, but its a part of c, and other optimization methods. Over all there has never been an extremely reliable and optimal way to tell if something is behind something else.
I am making a game and i have come across a hard part to implement into code. My game is a tile-bases platformer with lots of enemies chasing you. basically, in theory, I want my enemies to be able to, every frame/second/2 seconds, find the realistic, and shortest path to my player. I originally thought of A-star as a solution, but it leads the enemies to paths that defy gravity, which is not good. Also, multiple enemies will be using it every second to get the latest path, and then walk the first few tiles of it. So they will be discarding the rest of the path every second, and just following the first few tiles of it. I know this seems like a lot, to calculate a new path every second, all at the same time, if their is more than one enemy, but I don't know any other way to achieve what i want.
This is a picture of what I want:
Explanation: The green figure is the player, the red one is an enemy. the grey tiles are regular, open, nothing there tiles, the brown tiles being ones that you can stand on. And finally the highlighted yellow tiles represents the path that i want my enemy to be able to find, in order to realistically get to the player.
SO, the question is: What realistic path-finding algorithm can i use to acquire this? While keeping it fast?
EDIT*
I updated the picture to represent the most complicated map that their could be. this map represents what the player of my game actually sees, they just use WASD and can move around and they see themselves move through this 2d plat-former view. Their will be different types of enemies, all with different speeds and jump heights. but all will have enough jump height and speed to make the jumps in this map, and maneuver through it. The maps are generated by simply reading an XML file that has the level data in it. the data is then parsed and different types of tiles are placed in the tile holding sprite, acording to what the XML says. EX( XML node: (type="reg" graphic="grass2" x="5" y="7") and so the x and y are multiplied by the constant gridSize (like 30 or something) and they are placed down accordingly. The enemies get their frame-by-frame instruction from an AI class attached to them. This class is responsible for producing this path and return the first direction to the enemy, this should only happen every second or so, so that the enemies don't follow a old, wrong path. Please let me know if you understand my concept, and you have some thought/ideas or maybe even the answer that i'm looking for.
ALSO: the physics in this game is separate from the pathfinding, they work just fine, using a AABB vs AABB concept (the player and enemies also being AABBs).
The trick with using A* here is how you link tiles together to form available paths. Take for example the first gap the red player would need to cross. The 'link' to the next platform (aka brown tile to the left) is actually a jump action, not a move action. Additionally, it's up to you to determine how the nodes connect together; I'd add a heavy penalty when moving from a gray tile over a brown tile to a gray tile with nothing underneath just for starters (without discouraging jumps that open a shortcut).
There are two routes I see personally: running a quick prediction of how far the player can jump and where they'd jump and adjusting how the algorithm determines node adjacency or accept the path and determine when parts of the path "hang" in the air (no brown tile immediately below) and animate the enemy 'jumping' to the next part of the path. The trick is handling things when the enemy may pass through brown tiles in the even the path isn't a parabola.
I am not versed in either solution; just something I've thought about.
You need to give us the most complicated case of map, player and enemy behaviour (including jumping up and across speed) that you are going to either automatically create or manually create so we can give relevant advice. The given map is so simple, put the map in an 2-dimensional array and then the initial player location as an element of that map and then first test whether lower number column on the same row is occupied by brown if not put player there and repeat until false then same row higher column and so on to move enemy.
Update: from my reading of the stage generation- its sometime you create- not semi-random.
My suggestion is the enemy creates clones of itself with its same AI but invisible and each clone starts going in different direction jump up/left/right/jump diagonal right/left and every time it succeeds it creates a new clone- basically a genetic algorithm. From the map it seems an enemy never need to evaluate one path over another just one way fails to get closer to the player's initial position and other doesn't.
I have a "complex" problem where I have a bunch of tooltips (orange) on top of elements (black) that can be randomly placed on screen. The tooltips are a big square with a triangle in the middle of one of it's 4 sides pointing though the element direction. By default, the triangle will be in the middle of the element, but can be moved as long as it stay close to it, so we can't easily understand it refer to this element and not another one.
The problem is, the tooltip must NOT overlap each other, and can't be out of screen.
Image of my tooltip problem
I thought about first placing every tooltips to their default position (triangle pointing down), and then check if they are out of screen or overlap another one, and if so, try another position. But using this technique (which is probably the simplest one), I do not guarantee the best placement since once a tooltip has been placed, I will not replace him if another one can't fit anywhere otherwise it become too complex.
Does someone have any tips/idea how to deal with this type of problem?
Thanks!!
This looks like an instance of the map labelling problem. Wikipedia has an article about it.
You could place all the tooltips using some sort of physical simulation of repulsive electrical charges, similar to what is done in some algorithms for drawing graphs. You could model each tooltip as an object attached with a soft spring to its black box, while simulating a strong repulsive force between all the tooltips and between a tooltip and the edge of the image. You calculate all the forces and move the tooltips iteratively, until all positions converge. You could play with making the force scale as inverse square, inverse cube, etc to find nice results.
This might be a bit of work to implement, but should probably give decent results for simple cases. It is probably impossible to guarantee that a good solution always exists, since if you add too many tooltips, your image will be full.
My need is to draw a basic x-axis, y-axis plot of several lines, with the lines becoming known in sequence as the user enters data. jqPlot appears to have the ability (unlike flot, at least as I understand it) to add to an existing plot. My experimentation thus far is:
$.jqplot('dpCum',[ld.fCumPairFwd[0]],{axes:{xaxis:{min:0,max:2500},yaxis:{min:0,max:200000}}});
$.jqplot('dpCum',[ld.fCumPairAft[0]],{axes:{xaxis:{min:0,max:2500},yaxis:{min:0,max:200000}}});
which produces two lines as I want them, except the background of the 2nd obscures the the 1st line. In practice, the data for the 2nd line won't be known until the user responds to the 1st line, and then they're going to want to see both at once.
I've made a couple of passes at the jqplot documentation (it's capabilities are obviously impressive) but how to keep existing lines visible as new lines are added escapes me. I'm thinking there may be some kind of z-axis opacity, but haven't been able to understand it yet.
The answer to your problem, I believe, is to use the replot() method and paint a new plot with the modified data set.
This approach is presented in the following sample. Please notice I made only the series with index 0 responsive to clicks. On click on the series' data points another is painted.
EDIT: The reason I went for replot() was that I couldn't figure out how to draw just a single series. I tried the approach presented by #Mark here with no success. He might know better though. I am rather fresh to jqPlot myself. Also taking into account that when we add a new series some points might reach outside the current scale, therefore, since redraw() doesn't rescale as mentioned here by the jqPlot author - though in my case it will work since we reinitialize the graph. Thus, I think if you also will not manage to apply single series draw you might try using the redraw() method instead, taking from the doc I think it is less expensive to call.
Maybe actually in this case you will not use replot() or redraw(), as in the sample I am making a new plot each time. Therefore, it seems to me to be more appropriate to call destroy() on the previous graph before we paint the new one. This is what currently is in the code sample.