I am stuck trying to figure out how to alter my collision detection to work correctly, i got all my wall objects stacked inside a List and then when the player moves i loop thru each wall object and call the DetectCollision method, this returns true or false depending on if the object is inside the wall or not.
Wall detect collision (X- and Y-coordinate is the position of the wall)
public bool DetectCollision(float x, float y)
{
if ((x >= this.XCoordinate && x <= (this.XCoordinate + this.BlockWidth)) && (y >= this.YCoordinate && y <= (this.YCoordinate + this.BlockHeight)))
return true;
else
return false;
}
So in my player function when the player tries to move, i add the movement to a temporary X,Y coordinate and check if those Collide against the wall, if they do nothing happens, otherwise i move the player.
But i have noticed that it doesn't work as it should be, if i add a piece of wall inside of the gamefield it only checks the bottom right corner for collision detection?
Player movement method:
float x, y;
if (direction == Direction.E)
{
x = LiveObjects.player.XCoordinate - MovementSpeed;
y = LiveObjects.player.YCoordinate;
}
else if (direction == Direction.W)
{
x = LiveObjects.player.XCoordinate + MovementSpeed;
y = LiveObjects.player.YCoordinate;
}
else if (direction == Direction.N)
{
x = LiveObjects.player.XCoordinate;
y = LiveObjects.player.YCoordinate - MovementSpeed;
}
else
{
x = LiveObjects.player.XCoordinate;
y = LiveObjects.player.YCoordinate + MovementSpeed;
}
if (GameMechanics.DetectWallCollision(x, y) || GameMechanics.DetectWallCollision((x + LiveObjects.player.BlockWidth), (y + LiveObjects.player.BlockHeight))
{
OnPlayerInvalidMove(null, new PlayerEventArgs());
return;
}
and the loop for DetectWallCollision is just:
foreach (Wall wall in LiveObjects.walls)
{
if (wall.DetectCollision(x, y))
return true;
}
return false;
Any ideas?
I'm assuming there isn't anything in your world that is infinitely small (i.e. is the size of a pixel). To have true bounding box collision, you've got to consider the size of both objects, not just one.
boolean intersectsEntity(Entity e)
{
return (e.position.x <= position.x + size.x) &&
(e.position.y <= position.y + size.y) &&
(e.position.x + e.size.x >= position.x) &&
(e.position.y + e.size.y >= position.y);
}
That's of course assuming an Entity has a vector for its position and for its size. So size.x == width, and size.y == height.
There is something that disturbs me, you said that the DetectCollision method gets the position of the wall - but if I interpret your code correctly you hand to the DetectWallCollision the x and y parameter which is the position (after movement) of the player and hand that position down to the DetectCollision method...
have you debugged your code to see what coordinates are passed to the collision methods and traced the routes your if-statements are going?
if it is not possible to debug your code for whatever reason - write a trace file - I think the solution will fall into your lap ;)
Your east and west are the wrong way around. With a coordinate system of 0,0 at the top left, increasing positively as you move down or to the right, then a movement West would normally mean a movement left, which means decreasing values of X, and the reverse for East. You are doing the opposite.
Related
I'm working on replicating the game "Deepworld". I setup world gen using array maps and some special logic. I'm creating hundreds of objects in seconds. This destroys performance.
Even hitting the play button takes a while, and it's pretty hard to "exit" play mode, as it's basically 1 fps.
How should I go about culling everything not in the camera view. I don't understand any logic around the camera's view within C#.
If I knew more about how I could access the actual location and size of the camera's view, I could probably do something along these lines.
... {
for (int y = 0; y < height; y++) {
Vector3 pos = new Vector3(-width / 2 + x + 0.5f, objectHolder.transform.position.y, -height / 2 + y + 0.5f);
// Imaginary If Conditions Ahead
if (pos.x <= CameraViewMaxX && pos.x >= CameraViewMinX && pos.y <= CameraViewMaxY && pos.y >= CameraViewMinY) {
Gizmos.color = (map[x, y] == 1)? Color.white : Color.clear;
Gizmos.DrawCube(pos, Vector3.one);
if (map[x, y] == 0) {
Instantiate(block, pos, objectHolder.transform.rotation);
}
}
// Back to Normal
}
}
I don't know what direction to go in, and I don't know how to physically implement this into my game.
I know that I'm only supposed to load blocks in the view, like Terraria or Deepworld. That's the only reason those games run smoothly. It's because of the culling.
I am currently creating a brickbreaker clone (yeah, another) and have the ball-brick collision for 1 brick. I have 4 other bricks commented out, because when the ball collides with the brick I have the right code for, it just removes all bricks rather than the specific one it collided with. Also, the ball only collides with the first brick when the ball is near the top left corner of the game screen (pretty far from the actual brick). I'm really not sure what to do, I have tried spacing the bricks out a bit more but that didn't help.
int score = 0;
if ((ballY > picBrk1.Height) && (ballY < picBrk1.Height + 30) && (ballX > picBrk1.Width) && (ballX < picBrk1.Width + 71))
{
// ball rebounds off brick
yChange = -yChange;
// each brick adds 1 to score
score = score + 1;
lblScore.Text = "Score: " + score;
picBrk1.Visible = false;
}
You need to be very clear about the localisation of your bricks.
I suggest adding a UpperLeft property to your Brick class:
public class Brick
{
/* your other properties here */
public Point UpperLeft {get; set;}
}
Make sure UpperLeft value is properly set to the coordinates of the upper left corner of your brick.
My assumption is that your X and Y follow the standard computer image representation where 0,0 is the top left corner of the image and y increases when you go south (which is different from the usual mathematical standard).
Then your collision check will be:
Point ballRelativeToBrick1 = new Point(
ballX - picBrick1.UpperLeft.X,
ballY - picBrick1.UpperLeft.Y)
bool collide = 0 < ballRelativeToBrick1.X && ballRelativeToBrick1.X < picBrick1.Width
&& 0 < ballRelativeToBrick.Y && ballRelativeToBrick.Y < picBrick1.Height
I'm working on a small game, I have objects which I want to elevate up and down. Object moves to max value of Y -> Object moves to min value of Y -> Repeat. I have a rough idea of how to do this, I would put this in a timer/my update method.
if(Y >= max)
{
direction = "down";
}
if(y =< min)
{
direction = "up";
}
if(direction == "up") Y -= speed;
if(direction == "down") Y += speed;
(Could also use a bool ofcourse but, for the sake of implicity)
But it feels like I'm just re-inventing the wheel, is there by any chance a built in method/math function to do this automatically? eg. SomeFunction(min, max, increment).
I'm using the XNA framework, so functions built into that are ofcourse welcome as well.
Forget having a separate direction flag.
Just use a negative speed for "up" to simplify the code:
if ((Y >= max) || (Y <= min)) // Hit an edge?
speed = -speed; // Reverse direction.
Y += speed;
I have a bouncing ball application and I have to extend it to prevent overlapping of the balls.
When ball overlaps another, they should move away as in real life.
I have to extend the given MoveBall method:
private void MoveBall()
{
prevX = x;
prevY = y;
x += xVelocity;
y += yVelocity;
// Is there too closed ball?
foreach (Ball ball in parentForm.balls)
{
distance = Math.Sqrt(Math.Pow((double)(ball.prevX - prevX), 2) +
Math.Pow((double)(ball.prevY- prevY), 2));
overlap = ((radius + ball.radius) - distance);// +ball.radius;
if (ball.id != this.id &&
ball.id != lastID &&
overlap > 0)
{
lastID = this.id;
if (xVelocity > 0) // roading right
{
xVelocity = -xVelocity;
x -= xVelocity - ball.xVelocity;
}
else if (xVelocity <= 0) // roading left
{
xVelocity = -xVelocity;
x += xVelocity + ball.xVelocity;
}
if (yVelocity > 0)
{ // going up
yVelocity = -yVelocity;
y -= yVelocity - ball.yVelocity;
}
else if (yVelocity <= 0) // down
{
yVelocity = -yVelocity;
y += yVelocity + ball.yVelocity;
}
}
}
// ***********************************************
// ***************** END MY CODE *****************
if (x > parentForm.Width - 10 - (radius) || x < 0)
{
if (x < 0) x = 0;
if (x > parentForm.Width - 10) x = parentForm.Width - 10 - radius;
xVelocity = -xVelocity;
}
if (y > parentForm.Height - 40 - (radius) || y < 0)
{
if (y < 0) y = 0;
if (y > parentForm.Height - 40) y = parentForm.Height - 40 - (radius);
yVelocity = -yVelocity;
}
}
x,y, xVelocity, yVelocity, radius, prevX, prevY declared as int.
overlap, distance as double.
When 2 overlap, they are getting stuck. Why?
Unfortunately, I can't upload all source code because there are lot of modules.
I'm using Visual C# Express 2010.
As no Question is asked explicitly, I will assume the question "Why are the balls sticking together?"
You have only shown one loop in source code, that's not enough ;-) To check all possible collisions, you need to check n*(n-1)/2 possible collisions. That is normally done with two loops. You have to put in careful measures to avoid handling the same collision twice.
The reason that your balls get stuck is that you handle the same collision multiple times. For example two balls colliding exactly horizontal: The left one has velocity 5 and x-position of 100. The other one shall have a position of 110 and velocity of -6. When the collision happens:
x is set to 105.
Collision detected: x is set to 104 and velocity to -5.
The other Ball handles the same collision:
He moves according to his velocity to position 104.
Collision handling: His velocity becomes 6 and position becomes 105.
The balls were at 100 and 110 resp. and have been moved to 104 and 105. While the velocities are now pointing away from each other, the collision handling in the following step will invert them again. So the positions are close together and the velocities are changing sign every frame. The balls seem "stuck to each other".
I hope the answer helps you to understand your problem. For a better implementation of an elastic collision (that handles each collision exactly once) look here: Ball to Ball Collision - Detection and Handling
Having stumbled upon similar issues when I made my first attempts at collision detection algorithms, I'll try to describe what I think is the problem here.
Maybe the balls move fast enough so that, before collision is even detected by your code, they are already partially "inside" each other. When collision detection comes and notices that, it does what it's supposed to do: change the planned trajectories of the objects according to the details of the collision that just happened. The problem is that, because these objects got sort-of "merged" before collision detection caught them, they can't get unstuck because collision detection is fired again, trapping them with each other.
If this is the source of the problem, then maybe the above code would work with a small enough velocity vector. Of course, that's not a real solution, but if it does work for very small velocities, it probably confirms my hypothesis and you have some idea regarding how to proceed.
I have an array for the x co-ordinate of the bricks, an array for the y co-ordinates of the bricks and an array to show weather it is visible. My code reads like this:
if (Visible[0] == 1)
{
paper.DrawRectangle(pen, BrickX[0], BrickY[0], 50, 10);
}
and for my collision for the ball to hit the brick, the code reads:
if (Visible[0] == 1)
{
if ((x >= BrickX[0]) && (x <= BrickX[0] + 50))
{
if ((y >= picDisplayBat.Height - 190) && (y <= BrickY[0] + 10))
yChange = -yChange;
Visible[0] = 0;
This does not seem to work as when the ball comes close the brick, the brick dissapears before the collision has happened and the ball goes straight through it. any suggestions?
You're missing brackets around your second if test.
Regardless of the outcome of the test the brick gets set to invisible. Your code is effectively this:
if ((y >= picDisplayBat.Height - 190) && (y <= BrickY[0] + 10))
{
yChange = -yChange;
}
Visible[0] = 0;
You want this:
if ((y >= picDisplayBat.Height - 190) && (y <= BrickY[0] + 10))
{
yChange = -yChange;
Visible[0] = 0;
}
I won't answer your question exactly, but this might help.
It's kind of unobvious what your code does now. Why always [0]?
Just create a class called Brick and a class called Ball:
class Brick {
public double x, y;
public double size;
public bool visible;
};
class Ball {
public double x, y;
public double size;
};
Now introduce the member in the Brick called bool Intersects(Ball ball), which yields true if the ball intersects with the brick (you could simply check this by their bounding boxes).
Now your checks become extremely simple (I assume you have an array of bricks somewhere called bricks).
foreach (Brick brick in bricks) {
if (brick.visible && brick.Intersects(ball)) {
// Hide the brick
brick.visible = false;
}
}
In short, I think you are doing your steps out of order.
Your second routine is perhaps doing too much. It should only determine a collision, and return an identifier for the target of the collision. Then a consuming routine uses that information to adjust projectile trajectory (reflect it back) and finally turn-off the visibility.
By the way, collision detection is a popular venue for what is known as "double-dispatch" invocations. Consider using the visitor pattern (ala Gang of Four) as a way to code this up.