I am making small/mid RTS game, I have the following need:
I want Enemy Players to Attack allies and vice versa when they are in each attack range.
My question is: what would be a better approach finding if enemy units are in attack range of allied or vice versa of course ?
What have I tried:
For now I tried to add SKNodes with SKPhysicsBodies for each unit Node.
I can see that FPS are going down when the contact happens... I guess it wasn't the best way to know detect whether enemies are in range.
I guess my alternative is to run some Nested Loop within Update method and check if there are enemy units within the Radius.
I am not sure if it is the best approach, however with this approach I may play with some parameters and maybe optimize the routine for my own needs.
I would like to know if there is some better alternatives.
Look into GamePlayKit,
It may have some things you want.
Otherwise I would just use the Euclidiean Distance Formula https://math.stackexchange.com/questions/139600/euclidean-manhattan-distance without the square root, and use this value based on squads, not individual troops. (So if a group of 4 soldiers is attacking an enemy of 5 soldiers, only 1 distance check is done).
The reason why you do not square root, is because you should know the squared allowable distance. If an enemy 10 pixels away attracts soldiers, then use 100.
The best way to treat your soldiers like squads, add them all to an SKNode (sub class to add better functionality), then you just need to compare those squad SKNodes
If you want to reduce the number of checks you make, consider turning your play area into a grid (Like a chess board). Since you know the size of your tiles, you could easily check to see if the units are close enough to warrant a distance check. E.G. You have a unit at a1, and an enemy at i9, then you know just by tile distance that the units are too far apart to attack each other
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I am working on an AI mode for a SpriteKit game I am making in Xcode. I have dynamic physics bodies which can be launched towards the AI. I want to make it so that when one of these bodies is within a certain radius of the AI, the AI tries to dodge it. I have started working through different routes and got decent results.
1st method (pseudocode): Check AI.position.x and AI.position.y and compare to incomingSprite.position.x and incomingSprite.position.y. Break this comparison into quadrants if both x and y are within radius. (i.e. incomingSprite is bottom left relative to AI, bottom right, etc). Based on this info move the AI's position to move away from it.
cons:
-lots of code and calculations in update function to account for multiple incoming sprites
-depending on dx and dy of incoming sprite, the AI often make illogical decision
2nd method (pseudocode): Calculate distance from AI to incomingSprite. Then check dx and dy of incomingSprite and set dx and dy to go in reverse direction of incomingSprite. This seems logical. I am a little rusty on reversing vectors to do this. I feel like this might be possibly a good idea though.
Is there a better method to accomplish this? Perhaps a force field on the magnet I could use to repel the AI at a certain strength so that if the incomingSprite is fast enough it will override and still collide anyway? Im concerned about memory as most of the AI logic is in the update function, which can cause big problems if I'm not careful.
Edit: I decided to use the electric field and gave the incoming sprites a positive charge so that they are repelled by the AI. This makes things accurate/lightweight and more interesting. If the incoming sprites are fast enough, they will break through the electric field and still collide with AI. This also gives room as an additional difficulty parameter in my game (the stronger the field, the harder it is to get the incoming sprites to collide with the AI).
I'm trying to build an array of all player pawns that are in the players FoV cone. I'd prefer to not have to loop through GetAllActorsofClass for obvious performance reasons. This will be done every tick.
GetAllActorsOfClass iterates over a hash table of things of that class. Even with 100 players it is unlikely to be very costly. I would imagine that a "get actors in frustum" would just do that under the hood.
If you are okay with using it, from there you would use ConvertWorldLocationToScreenLocation and compare that to the screen bounds coordinates with GetViewportSize.
The only method the wouldn't use GetAllActorsOfClass I can think of offhand is to calculate the size of the rectangle at the "end" of the frustum, using a giant multi box trace, and filtering based on the dot product. Traces are cheap, dot product is cheap. Whether or not it's cheaper than GetAllActorsOfClass is going to be specific to your game.
If performance is really a problem the best solution is to use code. Depending on your implementation you might be able to use Blueprint nativization to get an extra boost without digging into code.
Use MultiSphereTrace from your player to his FOV direction and loop through hit results.
Make sure you set the collision layer correctly so the trace only interact with target player.
I do this on my mobile game with around 10-20 actors per frame, and it works fine.
I,m creating a dungeon generator in unity3d. I have a pile of prefabs(rooms, corridors, junctions). Randomly a piece is chosen for starting piece and then depending on the connecting rules next pieces are chosen. Also the dungeon can be multi layered. Like 1 room above the other etc. Problem is room collisions. On the same layer 2 rooms can be placed on top of each other and this is a problem.
My first idea was to use arrays to model the layers and then find best suiting locations for stairs up and down. But the problem with this is that not all angles are 90degrees. I have a 3 way intersection in the shape of Y. So everything that comes after this is angled. And its not easily represented on array.
Second idea was the use of collisions and backtracing. I place the tile and then if no collision I can move forward. But if collides I try to find a better suiting piece or remove the previous piece and but something new there. But I can't figure out a good method to do this.
Anyone have any suggestions or ideas on how to generate multilayered dungeons with non 90 degree angles?
I'm new to using xna and I want to make my player collide with with multipe walls from the same class. So I looked around and I understood that the best way for doing that is to create a list of variables containing the walls id's and make a loop that circles them all and then returns the variable of the objects that collide.
My question is if there is a faster more efficient way for doing that? I mean if I have like 10000 objects that loop can cause a lot of memory use.
Thx in advance
Option 1) If these 10000 object are walls of a level, then you should probably use some sort of grid (like this very old example: https://en.wikipedia.org/wiki/The_Legend_of_Zelda#mediaviewer/File:Legend_of_Zelda_NES.PNG)
With a grid you only have to check collision with adjacent objects, or only with objects that are nearby.
Option 2) If these 10000 objects are enemies or bullets that move more freely, then you could also calculate the distance first and only check for collision if the objects are nearby.
But may I ask why you are using XNA? I used to work with XNA 4.x but in my understanding it is pretty much dead (http://www.computerandvideogames.com/389018/microsoft-email-confirms-plan-to-cease-xna-support). If you're new to XNA, I would advice to use other software to make games (like Unity3D). In Unity3D the hard part of collision detection is done for you (is has standard functions for collision detection) and Unity3D also works with C# (like XNA)
You always want to do the least amount of processing to get the job done. For a tiled 2D game you usually have a 2 dimensional grid. When the player want to walk on a certain tile you can check that tile if it is allowed to walk there. In this case you just have to check a single tile. If you have a lot of NPC's you could divide your map into sections and keep track of in what sections the NPC's are. Now you just have to do collision detection on the enemies within your section.
When you need expensive collision, pixel perfect or polygon collision you should first check if an object is even close with a simple radius float or BoundingSphere only then you go on with more expensive collision detection.
Same goes for pretty much anything, if you have a 100x100 tilemap but only need to draw 20x10 for the screen then you should just render that portion by calculations. In unreal, mappers create invisible boxes, when inside these boxes it only draws a certain part of the map and only checks collision within these boxes. GameDev is all about tricks to make things work smoothly.
I think it would be fun to model a top view of a train following a track, traversing switches and so on, using a physics library like Box2D. What joints and motors would I need to make this work?
I'm curious about how to implement the forces needed to make the car follow a spline track so it can bump into other train cars, pedestrians, DeLoreans etc. Just saying "the car is now at spline(t)" for each time step would create excessive forces in the physics engine. If I understand correctly, you have to stick the car onto the track with one force, constrain its angle to tend towards parallel with the track with another (or stick the front and back of the car to the track with two forces), and create another force to propel the train forward. I'm looking for some details on how to accomplish these things.
I believe it would be easier without "real" physics, like the ball movement of games such as Luxor or Tumble Bugs. Meaning: let the train follow a spline which is defined by the tracks.
Using phyiscs is probably overkill to make a train follow a track and could lead to all kinds of undesired side-effects, including jerky motion, train derailing, train getting stuck on junctions, etc.
You could still join the individual wagons together using physic joints, however. Just make sure that only the locomotive gets acceleration forces, the rest of the train just follows or is pushed but stays on the spline.
Why are you worried about keeping it "on the tracks"? Where is it going to go? Gravity should keep it down, object intersection should keep it up, and so the only directions you need to worry about are forward and backwards. That's where a motor comes in, and you're done. The rest is decorations.
In response to edit of problem:
Siderails. And have the train long enough / rigid enough compared to its width that you can navigate crossings (make them closer to right angles to minimize the crossing problems.
A top-down view (i.e. seeing the train from the sky) doesn't really require a 2d physics engine - if I understand you correctly. In fact, it seems like it wouldn't really help with the problem (if you want a train simulation), but then maybe you just wanna try it out for fun. :)
However, what about putting something like a slider joint on the train and the cars, and a motor on the locomotive. The slider joint might need some special implementation; you probably want to run the train along a spline and not a segment of straight lines, right?
Some sort of ball joint would connect the cars together.
The implementation is not so toughand I was able to prototype something in a few hours that does the basic job. It will require a lot of work to make it run smoothly, but it's essentially just "siderails."
Being top-down you obviously first must turn off gravity in Box2D. Second, build a train. Treat train wheels like car wheels and it'll suddenly get a lot more simple. For tracks you have a few choices:
Create your own game object (not in the box2D world) that is a simple line the train will then "follow" (you can use motors on train wheels to "steer" towards the line). Then just overlay the line with some nice wide "rail" graphics and you have a nicely faked system. Tell the wheels to turn off if it strays too far from the line and presto, you have a derailment.
Create actual physical rails - outside rails (like siderails) that the trains "wheels" will bump into. They will have to have gentle curves in this instance, which could be very difficult given the limited resources you have (simulating a nice slow curve out of boxes in Box2D is rough on the processor)
Then just let your train go!