So, I've been working on a game for awhile, and I've run into a snag. I have no idea how to go about this. Here's my problem:
I have ship, with forward-facing railguns and two missiles. The railguns can only fire in a straight line in front of the ship, but the missiles can fire if a ship is anywhere in a cone in front of the ship. The problem, is that the ship is rotating and moving about the screen. For the railguns, I need to check if there's a ship anywhere in front of the ship on the screen. For the missiles, I need to check if there's a ship within 250px in front of the ship, but no more than 45 degrees to either side.
Any help you guys could give would be appreciated. Thank you!
For the railguns you could do somthing like this:
public delegate void inRange();
public event inRange shipInRange;
public void checkRange() {
if(enemyShip.position.x < ship.position.x + 250 ||
enemyShip.position.x > ship.position.x + 250)
shipInRange();
}
Although I haven't tested it yet, you should check if enemyship is 250 units behind or ahead of ship. This assumes that you are only moving your boats on the x axis. Although it would be easy to add the y axis, I also recommend a check for which direction you are facing, then put a event for each direction and listen to the one you are facing. That would probably be the easiest way.
Then all you have to do is to listen for that event, and do what you need to do when it happens. Same thing for the missile, but check the angle as well.
Also if you had some example code, I might be able to provide you with a better example.
Related
What I am trying to achieve at this point, is the following:
Let's say that we have a Cube game object and a SteamVR player.
The Cube object is on position y = 100 and the SteamVR player is on position y = 0.
I want to make it possible that the player can zoom in on the game object by doing the following:
-> Pressing both triggers and bringing the controllers close to each other will zoom in.
-> Pressing both triggers and bringing the controllers away from each other will zoom out.
I think u understand the effect that I want to create.
For my project I am using the SteamVR Unity plugin.
Could someone say me if this is possible and give me some insight on how to do this?
Thanks in forward.
Have an if statement checking for two inputs and move the camera position in the forward direction close and closer to the target. If you want to save the original camera position before zooming just store the Camera.main.forward before incrementing it.
pseudocode
public SteamVR_Input_Sources LeftInputSource = SteamVR_Input_Sources.LeftHand;
public SteamVR_Input_Sources RightInputSource = SteamVR_Input_Sources.RightHand;
public Vector3 currentZoom;
public Vector3 zoomAmount;
void update(){
if( SteamVR_Actions._default.Squeeze.GetAxis(LeftInputSource) && SteamVR_Actions._default.Squeeze.GetAxis(RightInputSource)){
currentZoom.forward += zoomAmount.forward; //increment zoom by whatever amount while
triggers are held
Camera.main.transform.forward = currentZoom;
}
}
I have not tested this, hence why I labeled it pseudocode, however, I hope this helps!
I am testing out some ideas in Unity where a player can walk around a circle while staying on it (so the circle has its own gravity) and also being oriented properly. This game is currently being done in 2D, so all objects are sprites.
I do hope I can explain myself properly. Please ask if you need any further clarification...
It appeared that I succeeded with my idea until I noticed something odd.
So as expected, the player moves around the circle without falling off (custom gravity worked just fine) and its Z rotation is affected as it aligns itself with a direction:
// Align code:
// We reverse the direction so the object is standing up the right way.
private void Update()
{
transform.up = -(planet.position - transform.position);
}
It works... mostly. However, when the player object's rotation Z naturally reaches 180, it appears to flip horizontally (like a mirror effect) and then it returns to normal as rotation Z leaves 180. The visual flip happens because for some reason the object's Y becomes 180 at the same time too. At no other point does X or Y change in regards to rotation. Only Z. So the moment Z hits 180, Y is affected and the moment we leave Z 180, Y returns to 0.
I'm happy to provide a quick video of it happening in-game if anybody needs some visual understanding of what's going on.
The visibility of this bug tends to rely on how fast you're moving around the circle. If you're moving fast enough, you can probably skip over 180 and not see it happen at all, however if you move slow enough there's no denying it's there. It's also problematic for the fact that I simply make the camera a child of the player so when the player flips, so does the camera causing the entire scene to flip which can look extremely glitchy for a player to see.
I really have no idea how to tackle this issue as I have no clue why it would do such a thing. At every other rotation value it behaves just fine. It's only at Z = 180 (so the object is exactly upside down) does it decide to rotate in the wrong ways.
EDIT: Changed tag to Unity3D
It's probably because of converting quaternions (which is what's actually used internally for rotations) to euler angles for display. Can you try to use Quaternion.Slerp to rotate?
I have a problem with AABB collision resolution.
I resolve AABB intersection by resolving the X axis first, then the Y axis.
This is done to prevent this bug: http://i.stack.imgur.com/NLg4j.png
The current method works fine when an object moves into the player and the player has to be pushed horizontally. As you can see in the .gif, the horizontal spikes push the player correctly.
When the vertical spikes move into the player, however, the X axis is still resolved first. This makes "using the spikes as a lift" impossible.
When the player moves into the vertical spikes (affected by gravity, falls into them), he's pushed on the Y axis, because there was no overlap on the X axis to begin with.
Something I tried was the method described in the first answer of this link.
However the spikes and moving objects move by having their position changed, not velocity, and I don't calculate their next predicted position until their Update() method is called.
Needless to say this solution didn't work either. :(
I need to solve AABB collision in a way that both of the cases described above work as intended.
This is my current collision source code: http://pastebin.com/MiCi3nA1
I'd be really grateful if someone could look into this, since this bug has been present in the engine all the way back from the beginning, and I've been struggling to find a good solution, without any success. This is seriously making me spend nights looking at the collision code and preventing me from getting to the "fun part" and coding the game logic :(
I tried implementing the same collision system as in the XNA AppHub platformer demo (by copy-pasting most of the stuff). However the "jumping" bug occurs in my game, while it doesn't occur in the AppHub demo.
[ jumping bug: http://i.stack.imgur.com/NLg4j.png ]
To jump I check if the player is "onGround", then add -5 to Velocity.Y.
Since the player's Velocity.X is higher than Velocity.Y (refer to the fourth panel in the diagram), onGround is set to true when it shouldn't be, and thus lets the player jump in mid-air.
I believe this doesn't happen in the AppHub demo because the player's Velocity.X will never be higher than Velocity.Y, but I may be mistaken.
I solved this before by resolving on the X axis first, then on the Y axis. But that screws up the collision with the spikes as I stated above.
Why not resolve on the Y-axis first for vertical spikes, and on the X-axis first for horizontal spikes?
Nice graphic, by the way.
As I understand it, you're handling movement and collision something like this:
Move all objects.
For each object O, test for intersection between the player and O, and if necessary, eject the player horizontally or vertically so that it is no longer intersecting with O.
If the player is still intersecting with some object, then (something).
This means that when you come to step (2), you have forgotten which way the object O was moving, so you can't tell if it is trying to push the player upwards or sideways.
Solution: in step (1), store for each object the direction it is moving. When you find the player intersecting with an object, you can look to see whether the object is moving up, down, left or right, and that will tell you which way to perform the ejection.
As Gareth Rees already said, the issue is after a collision is detected, you need more information (both current location and either direction came from or last position) to perform the collision response.
It gets quite complicated if both objects are moving. Instead, choose one object to be the frame of reference and subtract its velocity from everything else.
A straight forward solution might be to create line segments for the movement/delta of the non-frame-of-reference object. Then intersect those segments with the 4 AABB edges. This gives the time of intersection and the normal at the point of intersection. Then you can apply the same response you have now.
One possible solution I found is sorting the objects before resolving based on the velocity of the player.
I have the ball in the very right bottom side. When I click somewhere, I want to be able to figure out the direction I clicked and once the user starts to drag, I will calculate the distance. Once the user lets go of the mouse, I want to give the ball some velocity and have it move towards the direction it was first clicked.
I don't know the formulas to compute these things. Any help with explanation is greatly appreciated.
Thanks.
You can check the first mouse down Mouse.GetState() (I think) and save it to a variable. Then check, if the mousedown-state is still given (do this in the Update() function), if not, this will be your destination point. Now you have a starting point and destination point, so you can move your ball in the update-method through the destination point. I hope, the explanation is clear :)
I am writting a collision detection engine for my game and I have some problems.
Indeed, since I have several fixed rectangle and one moving (the player), I need to know which side of the fixed one was collided at first by the player, to replace him correctly.
The fixed rectangle are NOT in a grid so they can be placed anywhere on the map and they can have diffents size. They are not rotated.
The player class stores it's direction vector.
Any idea?
KiTe
In a nutshell:
You'll compare the Y and X components of the bounding rectangles to eachother to check for a collision. If the top(Y) of the player is less than the bottom of an enemy then you don't need to check anymore because it's not possible that they're colliding. If the right(X) side of the player is less than the left side of the enemy then they can't be colliding. It would help to define top, right, bottom, left of each object you intend to check inside the class. This will allow you to know which side is hit also. This should be enough to get you thinking and experimenting.
Have fun!
The name is "Axis-Aligned Bounding Box" collision detection.
Now you know the name, you can Google for the rest.
thanks to both of you for your help.
I've heard about AABB, but at first sight it didnt seem to fit to my needs (since I didn't understand it well).
But after writing down everything on papper, the solution I found appeared to be exactly the same as AABB !