/// <summary>
/// Places the player randomly on the battlefield.
/// If the player is inside the terrain, it is moved up until it is clear.
/// If no clear spot can be found, try a new random spot
/// </summary>
/// <param name="p">The player.</param>
public void PlacePlayer(Player p)
{
p.Velocity = Vector2.Zero;
p.Acceleration = Vector2.Zero;
Vector2 pos = new Vector2(rand.Next(Terrain.Width), rand.Next(Terrain.Height));
if (Terrain.IsPositionClear(pos + p.Origin))
{
p.Position = pos;
p.IsStandingOn = GroundTypes.Air;
}
else
{
int counter = 0;
do
{
pos.Y = (pos.Y - 1) % Terrain.Height;
counter++;
if (counter >= Terrain.Height)
{
pos = new Vector2(rand.Next(Terrain.Width), rand.Next(Terrain.Height));
counter = 0;
}
} while (!Terrain.IsPositionClear(pos + p.Origin));
p.Position = pos;
p.IsStandingOn = GroundTypes.Ground;
}
}
public static bool IntersectPixels(Matrix transformA, int widthA, int heightA, Color[] dataA, Terrain terrain, out Vector2 collisionPoint)
{
// Calculate a matrix which transforms from A's local space into
// world space and then into B's local space
// When a point moves in A's local space, it moves in B's local space with a
// fixed direction and distance proportional to the movement in A.
// This algorithm steps through A one pixel at a time along A's X and Y axes
// Calculate the analogous steps in B:
Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, transformA);
Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, transformA);
// Calculate the top left corner of A in B's local space
// This variable will be reused to keep track of the start of each row
Vector2 yPosInB = Vector2.Transform(Vector2.Zero, transformA);
// For each row of pixels in A
for (int yA = 0; yA < heightA; yA++)
{
// Start at the beginning of the row
Vector2 posInB = yPosInB;
// For each pixel in this row
for (int xA = 0; xA < widthA; xA++)
{
// Round to the nearest pixel
int xB = (int)Math.Round(posInB.X);
int yB = (int)Math.Round(posInB.Y);
// If the pixel lies within the bounds of B
if (0 <= xB && xB < terrain.Width &&
0 <= yB && yB < terrain.Height)
{
// Get the colors of the overlapping pixels
Color colorA = dataA[xA + yA * widthA];
// If both pixels are not completely transparent,
if (colorA.A != 0 && !terrain.IsPositionClear(new Vector2(xB, yB)))
{
// then an intersection has been found
collisionPoint = Vector2.Transform(new Vector2(xA, yA), transformA);
return(true);
}
}
// Move to the next pixel in the row
posInB += stepX;
}
// Move to the next row
yPosInB += stepY;
}
// No intersection found
collisionPoint = new Vector2(-1, -1);
return(false);
}
