Hey guys, I was looking into a simple flash game, and have a few enemies patrolling the area. I made each of them have a view angle of about 35 degrees, and a distance of 150 px. The problem is that they can see through walls. How would I check to see if a wall was in between the guard's view of the player?
I thought of ray tracing, but don't know a way to implement it. I also thought of maybe drawing a rectangle between the player and the guard, and collision check it against the walls, but again don't know how to implement it..
Any ideas?
Thanks,
Max
Just a thought.
Keep your code just as it is, but do a second test.
If it finds a target with your current code run another test to see if there is a wall between them with a ray type test.
This would keep your working code as it is and minimize the field for ray testingto the width of the target.
I think that you are not that far off.
Since your walls will probably be sprites or some other display object, you know their positions ect.
Then you could draw an opaque sprite with alpha 0 that embodies your enemy viewing range and then do a collision test on all walls and all viewing ranges.
This will also enable you to do a collision detection between the player and all enemy viewing ranges.
After a quick search this might be what you need
Cheers
Related
AS3 - Detect WHERE a collision occurred and ROTATE everything AFTER the collision point of the object by 90 degrees
DISCLAIMER
The following explanation probably makes no sense, so have a look at http://raphaelhennessy.com/misc/Explanation.png for more information
Essentially, I'm making a game where a lazer shines onto the screen and you have a mirror somewhere on the screen you can drag around. There is also a globe somewhere on the screen. The aim of the game is to direct the light, using the mirror, into the globe. Then, an animation plays of the globe filling with light and you progress to the next level.
After time, the levels get somewhat harder and new obstacles and challenges are introduced.
My problem is this; I got the lazer, mirror & globe all on the stage working fine except that I can't figure out how to programmatically make the lazer 'bounce' off the mirror.
Thanks in advance,
-Raph
I figured out how to do this. If you are interested you can find the code at raphaelhennessy.com/misc/LightStage.zip
I'm making a game similar to 'Run' (http://www.albinoblacksheep.com/games/run) but I can't quite figure out the floor part. I'm not wanting the sides and a ceiling like in 'Run', just the main floor.
I'm new to Flash game development (AS3) but I know the basics. I realise the character isn't moving and is just turning (the level itself moves). How do a make a continuous floor, do I have to make a very long .fla file, or do I have to do this with code?
All ideas and help appreciated, Thanks. =)
You should use Tiles. Basically, a tile game consists of a lot of squared tiles, which are inserted when appear in screen and removed when goes out.
In your case, maybe you could use a big tile, with screen's size.
You can visualize a good example here, also a very good resource for gamedev on Flash.
You need to generate sprites of the edge of the screen and either recycle them when their x < some value or dispose and create new ones.
I think you can just use Bitmap.draw() to draw different pixels on a Bitmap that you've applied a 3D transformation to. You can see the basic concept illustrated here.
Or that's what I think, at least.
I just began with AS3 and I'm trying to do a little game where one ball moves on its own and the other one is handled by the player. So far, so good. That works.
What isn't working is hitTestObject(); it just returns true when it's like 2 cm from the other object. Here's a picture so you can see: http://dl.dropbox.com/u/37057843/coll2.jpg
I've read that hitTestObject just creats a rectangle around the objects and then tests for collisions on those rectangles, is it because of that?
If you need any piece of code I'll deliver. I know there are some other opensource libraries/engines like Box2D to solve this in a better way, but I don't want to jump to engines directly.
Thanks for reading!
Yes, hitTestObject will use the clips bounding box.
Check out this link, it has a lot of great information as well as a class that will do what you're looking for
http://sierakowski.eu/list-of-tips/39-collision-detection-methods-hittest-and-hittestobject-alternatives.html
Direct link to the package
http://code.google.com/p/collisiondetectionkit/
I have an array of points that I will use to generate a closed polygonal fence on the outside of a game stage (2D). I wish to have collision detection between this fence and a bouncing ball-like object on the inside.
Additionally, I would like to be able to arbitrarily add/remove/redraw the fence in realtime and have the collision detection still operate realistically.
I have considered drawing a Sprite/Shape from the points and doing a HitTest at each frame to check whether to bounce or not.
My question: is this the best/correct way to accomplish this goal? Consider something like JezzBall with diagonal lines of any angle a simulation of what I'm trying to do.
Check the corners of your bouncing ball with four hitTestPoints. If it succeeds, then do hitTestPoints from the fence with shapeflag set to true.
There may be better solutions as I do not know the performance impact of shapeflag, but combined with the corners optimization I think it will be good, but I'm also interested if there is a better way.
Math will be your friend here. Do a quick search for circle-line, or point-line collision (here's one: Circle line-segment collision detection algorithm?).
What you do is run through your array of points, creating lines. So line 1 will be points[0] and points[1], and line 2 will be points[1] and points[2]. After that you check each line against your ball (if you want proper collision that will work no matter the frame rate, then you create a ball line, which is the line that the ball has travelled along between the last frame and this one). Do your collision detection against the ball line and each line made from your points (there's tons of line-line collision detection algos on the web). What you'll get out of an algorithm like that is the time the collision takes place in the current time step, as well as the normal of the colliding line, which will give you the reflection angle.
If you don't know Vector math, then learn it, it'll make your life a ton easier. Again, there are tons of implementations of a Vector2 class on the net.
You can arbitrarily remove parts of the wall as needed by just ignoring those points in your check.
Another lazy solution would be to use a physics engine like Box2D http://box2dflash.sourceforge.net/ or Nape: http://code.google.com/p/nape/ - it might be overkill for what you want for your game, but hey, it's easy.
For bonus points, another technique which might be easier for you is the Separating Axis Theorem, which is used in the flash game N: http://www.metanetsoftware.com/technique.html
I'm trying to create a multi-level dungeon adventure in Flash CS4. The layout is an instance created of a symbol called Level, within the symbol are multiple wall subsymbols (wall), instances of Wall. There is a collision routine to stop the player walking through the walls, called from Wall.As.
Level is drawn about the centre point (0,0).
When I create an instance on the stage of Level (level), the collision tester is using the xy coordinates for the walls drawn about 0,0, not the "real" xy where it's appearing on the stage.
So what I need to know, is how to "update" the xy for each wall subsymbol with the live stage information, overriding the XYs drawn in the parent. It has to be updated unfortunately (I can't keep it static), as the levels are big so have to scroll.
Thanks for your advice.
With all due respect forget your approach, you're reinventing the wheel for nothing and probably to end up getting worse performance. What you need is pixel-perfect collision detection and probably including basic physics so already we're talking a huge amount of work. If you want to build levels in a design way for a game, use this, it'll blow your mind how awesome/easy/cool this is:
http://www.gotoandlearn.com/play.php?id=135
Its always a guess when trying to answer questions like this, as there are a lot of unknowns. That being said, in programming, there are always more than a few ways to solve a problem. Examine your collision detection routine - if you worked with hitTestPoint, and the point that was being tested (mouseX,Y or your main actor) with localToGlobal, you likely wouldn't need to test for the x,y variables of your collision objects. Read up on those two subjects and this question might be rendered moot.
At any rate, you could update relative coordinates in your Wall.as instance by leveraging globlaToLocal:
public function get curLoc():Point
{
return globalToLocal(new Point(this.x, this.y));
}
and retrieve them from your parent class as a point you can then test against:
trace(_wall.curLoc);
Hope that helps
I suppose you could accomplish what you're trying to do by manipulating the transform property of the wall symbols, but honestly I would concur with Ascension Systems and just abandon your collision testing routine for something different.
You may not need to go all out with a physics engine for your game, in which case just use hitTestObject to do the collision detection.