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Andy474

[XNA] Problem with 2D Pixel Collisions

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Andy474    694
Hey guys, quick overview of what im attempting. I have a Player sprite draw on the screen, this is rotated to follow the mouse.

I also have a collision map, which is constructed by passing an int[,] to genreate a texture using a render target. So I end up with a collision Texture.

I am trying to detect a collion with this Collision texture and seem to be going wrong. I have followed the tutorial here App hub

public bool CanMove(Player player, Camera camera, Vector2 moveDir)
{
/* Todo:
* Calulate the Rectangle of the Player
* Move this rectangle by MoveDirection to get the Rectangle on the Collision Map we want to get
* Check these two Rectangles for pixel Collisions
*/


// Calulate the Rectangle of the Player
Matrix rotationmatrix = Matrix.CreateRotationZ(player.Rotation);
Rectangle boundingPlayer = player.GetCollisonRect();

// Move this rectangle by MoveDirection to get the Rectangle on the Collision Map we want to get
Rectangle collisionRect = new Rectangle(
boundingPlayer.X + (int)moveDir.X,
boundingPlayer.Y + (int)moveDir.Y,
boundingPlayer.Width,
boundingPlayer.Height);

//Get the Color Data for each of these Rectangles
Color[] playerData = new Color[player._tPlayerTexture.Width * player._tPlayerTexture.Height];
player.GetTextureData(playerData);
Color[] CollisionData = new Color[_collisionTexture.Width * _collisionTexture.Height];
CollisionData = GetPixelData(collisionRect);

//Rotate both these Rectangles
//boundingPlayer = CalculateBoundingRectangle(boundingPlayer, rotationmatrix);
//collisionRect = CalculateBoundingRectangle(collisionRect, rotationmatrix);


// Check these two Rectangles for pixel Collisions
//Check them to see if they intersect to avoid useless calcs
if (boundingPlayer.Intersects(collisionRect))
if (IntersectPixels(boundingPlayer, playerData, collisionRect, CollisionData))
return false;

//We say we always can move, unless we already broke out
return true;
}


The full Code File

This function supposed to decide if the Player can mvoe, however there are a few problem I am stuggling to get my head around.

1/ When I DONT rotate the Collision Rectangle

//boundingPlayer = CalculateBoundingRectangle(boundingPlayer, rotationmatrix);
//collisionRect = CalculateBoundingRectangle(collisionRect, rotationmatrix);

My player can move, but not close to the Collision wall at all and then he gets stuck and cant move

2/ If I uncomment the lines and move the rectangle (i get an array out of bounds excecption in the Intersect Pixels function

I am pretty sure i am just not approching it properly or doing simthing stupid, can anyone help me out? its been buggin me for hrs now hehe

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