XNA Simple Tile Map collisions - c#

I'm new at this and I'm making a very simple 2D platformer with a level is loaded from a text file. I'm having trouble to try how to figure out how I can have my character sprite collide with the tiles.
This is an example of a .txt that my game will run:
1,1,1,1,1,1,1,1,
1,1,1,0,0,0,0,1,
1,1,0,0,0,1,0,1,
1,0,0,0,0,1,1,1,
1,0,0,0,0,0,0,1,
1,0,0,0,1,0,0,1,
1,S,0,1,1,0,F,1,
1,1,1,1,1,1,1,1,
I've managed to figure out how to successfully draw them onto the page, but cannot progress further.
My current model has my character colliding with the edge of the screen by having a boolean for Collision equal to true when the edge of the sprite touches the edge of the screen and setting its velocity to 0, but I'm not sure how to do that to block that are generated from a .txt
My current model of drawing a level looks like this:
if (currentState == GameState.Playing)
{
for (y = 0; y <= 7; y++)
{
string[] mapchars = maplines[y].Split(','); //where maplines is each row of characters and mapchars is each individual character//
for (x = 0; x <= 7; x++)
{
if (mapchars[x] == "1")
{
spriteBatch.Begin();
spriteBatch.Draw(block, new Vector2((200 + (50 * x)), ((50 * y))), Color.White);
spriteBatch.End();
}
if (mapchars[x] == "F")
{
spriteBatch.Begin();
spriteBatch.Draw(block, new Vector2((200 + (50 * x)), ((50 * y))), Color.Yellow);
spriteBatch.End();
}
if (mapchars[x] == "S")
{
spriteBatch.Begin();
spriteBatch.Draw(sprite, new Rectangle((200 + (50 * x)), ((50 * y)), 40, 40), Color.White*0.5f);
spriteBatch.End();
}
if (x > 7)
{
break;
}
}
if (y > 7)
{
break;
}
}
}
Where maplines[] is each line of the .txt and where mapchars[] is for each individual character on each line.
If anyone knows a solution to this problem, it would be a great help :)
Thanks.

Don't do that like this ! You are wasting a lot of speed with a game coded like this. I have an issue for you.
First, get all your .txt map into a string[] wich is line is an string. Do that with the method File.ReadAllLines(string yourtxtfilepath).
Once you have done this, create an new 2 dimensional array of Block (Block[,]). You have to create an general abstract class Block wich all your types of blocks (rock, air, grass ...) inherits from its.
Create a for loop who checks all chars in all the string of the array of string you got. In that loop check if the character is an '1' or an 'F' or something else by a case statement. For example, if it was an 'F' add a new GrassBlock to your Block 2 dimensional array.
Finally, after the loop you get your map in your 2 dimensional Block array, wich is perfect to get access to all your blocks in the map.
Just put a foreach loop in the Draw() method to draw each block to your screen by incrementing their positions by the width and the heights of your tiles.
If you don't understand what I said, just do some Google searches to get the necessary knowledge so you will understand. Start by acknowledge what I try to explain you and after, you can concentrate yourself on collisions, wich is more advanced.

Related

Object spawn on procedural terrain spawns on unspecified area

I've managed to put together a procedural terrain with defined regions and I am looking to procedurally place objects within the world within these regions. The regions are defined by their height and I am trying to utilise this to correctly place certain objects in certain regions however my result seems to come out slightly odd where objects are able to spawn outside the defined region height. I am using an AnimationCurve as a mesh height curve to prevent water areas from becoming terrain like. I am unsure if this is causing the issue behind in the correct placement. Would appreciate any insight into where I might be going wrong
Defined regions:
The Rock region is defined with a height of 0.7 and I try to spawn trees on the map only at a Rock location
Spawning object (Spawn 10) at rock location
int amount = 0;
for (int y = 0; y < mapHeight; y++)
{
if(amount < 10)
{
for (int x = 0; x < mapWidth; x++)
{
float currentHeight = noiseMap[x, y];
if(currentHeight.ToString("f1") == (0.7f).ToString())
{
Debug.Log(currentHeight.ToString("f1"));
Vector3 spawnPosition = new Vector3(Random.Range((x), (mapWidth / 2)), currentHeight, Random.Range(y, (mapHeight / 2)));
var block = Instantiate(AssetsToSpawn[0].AssetPrefab, spawnPosition, Quaternion.identity);
block.transform.SetParent(this.transform);
amount++;
break;
}
}
} else
{
return;
}
Result
Some seem to spawn in the right location albeit looking slightly weird but the one on the far left is finding itself on flat land, with water and sand; an area not defined as 0.7 or Rock type.
I think the issue lies in the line
Vector3 spawnPosition = new Vector3(Random.Range((x), (mapWidth / 2)), currentHeight, Random.Range(y, (mapHeight / 2)));
you seem to already iterate your map grid using x and y so why pick random positions on your map that might be anywhere between this current position and the center of the map?
I think you would rather want a random position within the current field and do e.g.
Vector3 spawnPosition = new Vector3(x + Random.Range(-0.5f, 0.5f), currentHeight, y + Random.Range(-0.5f, 0.5f));
Besides that why go through strings in
if(currentHeight.ToString("f1") == (0.7f).ToString())
I see that it's probably for the rounding but I would still prefer to rather do e.g.
if(Mathf.Abs(currentHeight - 0.7f) <= 0.05f)
which would have about the same effect but the threshold is better to control.
However, sounds to me like rock rather would be anything between 0.49 and 0.7 actually so actually it should be
if(currentHeight > 0.49f && currentHeight <= 0.7f)
Finally, unless you store somewhere which map position you already populated with a tree your outer for loop will always over and over enter at the exact same grid position, the first one that is encountered to fulfill your inner loop's condition!
So far you where always using the exact se position for all 10 trees, only the random position caused that it didn't seem so.

Unity chess game problem with friendly piece collision

Hi im building a chess game in Unity and my issue is that the queen can move above a friendly piece.
When a piece is selected, an array of legal moves on the board is generated
legalMoves = piece.Move();
I chose to work with vectors here so any move within the list is a 2d Vector.
Then in a loop, I check if any of the moves are within the boundaries of the board and if the move would place the piece on another friendly piece. If it does, then discard that move but my problem is that it should discard all the moves within that direction.
For example: if the queen is on (3,3) and there is a pawn on (3,5), then all the moves (3,6), (3,7) ... should be discarded but not (3,4).
Similarly, if the black queen is on (7,7) and a pawn is on (7,5) then all moves (7,4), (7,3), (7,2) .. should be discarded but not (7,6).
My intuition here was that when a vector has a friendly piece on it, check the direction and the length of all my legal moves against it:
if (dir.normalized.Equals(temp[j].normalized) && dir.SqrMagnitude() < temp[j].SqrMagnitude())
The idea was to remove all the vectors from the legalmoves with the same direction but with greater length, however this doesn't really seem to work because the normalized vectors will not be equal.
Here is the relevant code
foreach (var dir in legalMoves)
{
if (0 <= dir.x && dir.x <= 7 && 0 <= dir.y && dir.y <= 7)
{
//TODO shrink this to 1d array search
if (board[(int) dir.x, (int) dir.y].getPiece() == null)
{
Instantiate(trail, dir, Quaternion.identity);
}
else
{
List<Vector2> temp = legalMoves.ToList();
GameObject[] trails = GameObject.FindGameObjectsWithTag("bullet");
for (int j = 0; j< temp.Count; j++)
{
if ( dir.normalized.Equals(temp[j].normalized) && dir.SqrMagnitude() < temp[j].SqrMagnitude())
{
foreach(var t in trails)
{
// remove trail
if (t.transform.position.Equals(temp[j])) Destroy(t);
}
// remove the move with the same direction
temp.Remove(temp[j]);
}
}
temp.Remove(dir);
legalMoves = temp.ToArray();
}
}
}
here is my problem visualized chess collision issue
Ok, maybe there could be a better solution, however, the way I managed to do it is the following:
Our queen = q is at (3,0) , obstructed piece = k is at (3,6),
If we calculate the offset from k to q we always get an axis which is 0 (either x or y ) in this case it is x.
Since we know an axis is 0 we can check which one is 0 using a boolean, in this case it is x, and simply discard all the legal moves which are on x and above 6 or below 6 for black pieces.
I haven't thought about how to do it if a piece obstructs horizontally, however I'm sure its just a matter of adding/ substracting the right coordinates as above.

C# - Per Pixel Collision Detection

Here's my situation I'm making a 2D maze game(XNA 4.0). I have figured out that the best way to do collision detection is by using per-pixel detection. While searching it up on the internet I have found people explaining or showing code for two things colliding(i.e. mouse & player, player & player, two shapes). What I would like to do is have this collision detect whether the player collides with a wall or not(the background is black but the maze walls are white). Could someone explain how to do this or to give some sort of starting point with the code. Much Appreciated.
P.S. A link to a website or anything relating to my question would also be helpful
The best way to go about this CPU-intensive operation is checking for hitbox collision first, then the per-pixel collision.
Most of this code can be found in this helpful video.
static bool IntersectsPixel(Rectangle hitbox1, Texture2D texture1, Rectangle hitbox2, Texture2D texture2)
{
Color[] colorData1 = new Color[texture1.Width * texture1.Height];
texture1.GetData(colorData1);
Color[] colorData2 = new Color[texture2.Width * texture2.Height];
texture2.GetData(colorData2);
int top = Math.Max(hitbox1.Top, hitbox2.Top);
int bottom = Math.Min(hitbox1.Bottom, hitbox2.Bottom);
int right = Math.Max(hitbox1.Right, hitbox2.Right);
int left = Math.Min(hitbox1.Left, hitbox2.Left);
for(y = top; y< bottom; y++)
{
for(x = left; x < right; x++)
{
Color color1 = colorData1[(x - hitbox1.Left) + (y - hitbox1.Top) * hitbox1.Width]
Color color2 = colorData2[(x - hitbox2.Left) + (y - hitbox2.Top) * hitbox2.Width]
if (color1.A != 0 && color2.A != 0)
return true;
}
}
return false;
}
You can call this method like so:
if (IntersectsPixel(player.hitbox, player.texture, obstacle.hitbox, obstacle.texture))
{
// Action that happens upon collision goes here
}
Hope I could help you out,
- GHC
Create a matrix of bools representing your sprite and a matrix of bools representing your maze (the matrix representing your sprite needs to have the same dimensions as your maze).
then you can do something simple like iterate over all x-y coordinates and check whether or not they're both true
// as an optimization, store a bounding box to minimize the
// coordinates of what you need to check
for(int i = 0; i < width, i++) {
for(int j = 0; j < height, j++) {
if(sprite[i][j] && maze[i][j]) {
collision = true
//you might want to store the coordinates
}
}
}
If you want to be very fancy you can flatten your maze matrix and use bit operations

How to find a path from source to target with obstacle avoidance

Actually my robot wants to move from source to target with obstacle avoidance. I find out the obstacle(rectangle shape) and Target(circle shape) in pixels. But i don't know how to find the path from source to target... Please help me.
Here is the code for finding obstacle and target.
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
AForge.Point center;
float radius;
// is circle ?
if (shapeChecker.IsCircle(edgePoints, out center, out radius))
{
g.DrawEllipse(whitePen, (float)(center.X - radius), (float)(center.Y - radius),
(float)(radius * 2), (float)(radius * 2));
target.Add(center.ToString());
}
else
{
List<IntPoint> corners;
// is triangle or quadrilateral
if (shapeChecker.IsConvexPolygon(edgePoints, out corners))
{
// get sub-type
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Unknown)
{
pen = (corners.Count == 4) ? redPen : bluePen;
}
else
{
pen = (corners.Count == 4) ? greenPen : brownPen;
}
g.DrawPolygon(pen, ToPointsArray(corners));
}
}
}
This above coding will detect obstacle and target position pixel values and store it in a seperate array. But from these pixel values how to calculate the path? Waiting for ur suggestions.....
Trying looking up the A* search algorithm.
I have not looked into your code but it is a classic path finding problem. One suggestion could be to map the entire area the robot moves onto a grid. The grid can have discrete cells. And then you can use any graph search algorithm to find a path from start cell to goal cell.
You can use few of the algorithms, like Dijkistra, Best-first and A-Star search algorithms. It turns out that A-Star is efficient and easy to implement. Check this, contains a nice explanation about A-Star.

Simpler way to check for collision?

I'm working on an assignment for uni where I have to create a Breakout game in Visual Studio 2010 using C# Win Forms. At the moment, I am concentrating on there being only one brick to be destroyed so I have the mechanics down before expanding on it.
To clarify about my current program: I am using a picture box as a Graphics object and a timer to create the animation effect. The ball can skip, at each frame, between 1 and 10 pixels — this is part of creating a random starting vector for the ball.
This works fine until it comes to checking if the ball has 'hit' the brick I have drawn. What I have is an if statement that checks if the ball is at any of the coordinates on the picture box that corresponds to the outline of the brick. I know that the logic is fine because it works some of the time. However, because of the variation in the 'jumping' of the ball's position, I need to add a buffer area of +/- 5 pixels to my if statement.
This is where the problem arises, because my if statement (two, really) is really complicated as it is:
// Checks if ball hits left side or top of brick
if (((x >= brickX) && (x <= (brickX + 50)) && (y == brickY)) ||
((y >= brickY) && (y <= (brickY + 20)) && (x == brickX)))
{
brickHit = true;
}
// Check if ball hits right side or bottom of brick
else if ((((x >= brickX) && (x <= brickX + 50)) && (y == (brickY + 20))) ||
(((y >= brickY) && (y <= brickY + 20)) && (x == brickX + 50)))
{
brickHit = true;
}
For clarification: x and y are the coordinates of the ball and brickX and brickY are the coordinates of the top-left corner of the rectangle brick (which is 50 pixels wide, 10 pixels high).
Is there any way to simplify the above if statements? If I can make them simpler, I know it'll be much easier to add in the 'buffer' (which only needs to be 5 pixels either side of the brick's outline' to allow for the ball's change in position).
If further clarification is needed, please ask — I'm writing this question at 5:12am so I know I might be a little unclear.
One way you could possible simplify this (and I may be misunderstanding your spec), but you can make a Rectangle out of the bounds of the brick and check the Contains for your x,y point.
Rectangle rec = new Rectangle(brickX, brickY, 50, 20);
rec.Offset(-5, -5);
rec.Inflate(10, 10);
if (rec.Contains(new Point(x,y))
{
brickHit = true;
}
brickHit = new Rectangle(brickX,brickY,50,20).Contains(x,y);
Adding a buffer:
int buffer = 5;
brickHit = new Rectangle(brickX,brickY,50,20).Inflate(buffer,buffer).Contains(x,y);
The Rectagle class can come in handy sometimes.
This worked for me:
var rect1 = new System.Drawing.Rectangle(pictureBox1.Location,
pictureBox1.Size);
var rect2 = new System.Drawing.Rectangle(pictureBox2.Location,
pictureBox2.Size);
if (rect1.IntersectsWith(rect2))
{
//code when collided
}

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