Popped

[paul_nicholls]

I know it's a very last minute thing, but I've started my entry for the compo...it's called "Popped". It's going to be a tilt the world game to guide a bubble around the world past hazards and stuff trying not to get popped.

cheers,
Paul

[Carver413]

sound's like a fun game Paul

[paul_nicholls]

Thanks
I have done bugger all so far, so we will see! haha

[paul_nicholls]

I have a collision question for in my game if anyone can help?

I want to stop the circle (bubble) when it hits a sloped tile (45 degrees) moving either up / down / left / right. I can do square tiles, but not sure how to do sloped:

|\       __
|_\      \ |
          \|
___
| /       /|
|/       /_|

Here is a screenshot (includes gravity vector when tilting world) which shows the sloped tiles as well as the square tiles:



This is my collision code for square tiles which I hope to add sloped tiles to:

var
  Corners: SpriteCorners := new SpriteCorners;

method PoppedApp.GetBubbleCorners(aOfsX,aOfsY: Single): SpriteCorners;
begin
  // calculate tile index for each object corner
  Corners.Left   := FLevel.getTileX(FBubble.pos.x - FBubble.radius + aOfsX);
  Corners.Right  := FLevel.getTileX(FBubble.pos.x + FBubble.radius - 0.001 + aOfsX);
  Corners.Up     := FLevel.getTileY(FBubble.pos.y - FBubble.radius + aOfsY);
  Corners.Down   := FLevel.getTileY(FBubble.pos.y + FBubble.radius - 0.001 + aOfsY);

  // if true then there is a wall there
  Corners.WallUL    := FLevel.wallAt(Corners.Left  ,Corners.Up);
  Corners.WallUR    := FLevel.wallAt(Corners.Right ,Corners.Up);
  Corners.WallDL    := FLevel.wallAt(Corners.Left  ,Corners.Down);
  Corners.WallDR    := FLevel.wallAt(Corners.Right ,Corners.Down);

  Result := Corners;
end;

method PoppedApp.MoveBubble(aTimeSlice: Single);
var
  cnr: SpriteCorners;
begin
  cnr := GetBubbleCorners(0,FBubble.vel.y*aTimeSlice);

  if FBubble.vel.y < 0 then
  // moving up
  begin
    if not cnr.WallUL and not cnr.WallUR then
    // not obstructed so move normally
      FBubble.pos.y := FBubble.pos.y + FBubble.vel.y * aTimeSlice
    else
    // hit tile so move to edge of tile and stop
    begin
      FBubble.vel.y := 0;
      FBubble.pos.y  := cnr.Up * cTileSize + cTileSize + FBubble.radius;
    end;
  end
  else
  if FBubble.vel.y > 0 then
  // moving down
  begin
    if not cnr.WallDL and not cnr.WallDR then
    // not obstructed so move normally
      FBubble.pos.y := FBubble.pos.y + FBubble.vel.y * aTimeSlice
    else
    // hit tile so move to edge of tile and stop
    begin
      FBubble.vel.y := 0;
      FBubble.pos.y  := cnr.Down * cTileSize - FBubble.radius;
    end;
  end;

  cnr := GetBubbleCorners(FBubble.vel.x*aTimeSlice,0);

  if FBubble.vel.x < 0 then
  // moving left
  begin
    if not cnr.WallUL and not cnr.WallDL then
    // not obstructed so move normally
      FBubble.pos.x := FBubble.pos.x + FBubble.vel.x * aTimeSlice
    else
    // hit tile so move to edge of tile and stop
    begin
      FBubble.vel.x := 0;
      FBubble.pos.x  := cnr.Left * cTileSize + cTileSize + FBubble.radius;
    end;
  end
  else
  if FBubble.vel.x > 0 then
  // moving right
  begin
    if not cnr.WallUR and not cnr.WallDR then
    // not obstructed so move normally
      FBubble.pos.x := FBubble.pos.x + FBubble.vel.x * aTimeSlice
    else
    // hit tile so move to edge of tile and stop
    begin
      FBubble.vel.x := 0;
      FBubble.pos.x  := cnr.Right * cTileSize - FBubble.radius;
    end;
  end;

  // apply gravity
  FBubble.vel.x := FBubble.vel.x + FGravityX * aTimeSlice;
  FBubble.vel.y := FBubble.vel.y + FGravityY * aTimeSlice;

  // don't allow bubble to move faster than maximum velocity
  if FBubble.vel.VecLen > cMaxVel then 
  begin
    var m   : Single := FBubble.vel.VecLen;
    FBubble.vel.SetValue(FBubble.vel.x * cMaxVel / m,FBubble.vel.y * cMaxVel / m);
  end;
end;

cheers,
Paul

[SilverWarior]

You should do line to circle colision detection for this. http://stackoverflow.com/a/1079478

[paul_nicholls]

You should do line to circle colision detection for this. http://stackoverflow.com/a/1079478

Thanks mate, I will take a look at it

cheers,
Paul