Keep both players in shot

OpenGL Development
#1

If I want to keep both player in the screen at all times no matter how far apart, how can I do this with GLOrtho?

I am trying to calculate the distance between them +the player width but im not sure how to tell the camera to display that width and center (distance between players /2)

#2 

double minX = Math.min(player1.x, player2.x) - 10;
double minY = Math.min(player1.y, player2.y) - 10;
double maxX = Math.max(player1.x, player2.x) + 10;
double maxY = Math.max(player1.y, player2.y) + 10;

double dx = maxX-minX;
double dy = maxY-minY;


double aspectRatio = dx / dy;

double WANTED_ASPECT_RATIO = (double)screenWidth/screenHeight;

if(aspectRatio < WANTED_ASPECT_RATIO){
    double centerY = minY + dy*0.5;
    double correction = dx*0.5 * WANTED_ASPECT_RATIO;
    minY = centerY - correction;
    maxY = centerY + correction;
}else{
    double centerX = minX + dx*0.5;
    double correction = dy*0.5 / WANTED_ASPECT_RATIO;
    minX = centerX - correction;
    maxX = centerX + correction;
}


glOrtho(minX, maxX, maxY, minY, -1, 1);

COMPLETELY UNTESTED. IF IT WORKS, I’LL BE SURPRISED.

#3

VERY quick and detailed reply! but this zooms the camera in about 1000% and puts the camera in the top right LEFT. I will fiddle with it and get back to you :smiley:

Thanks

#4

Geh! I knew it! =S

To describe what I was trying to do:

  1. calculate a bounding box around the units (first 4 lines)
  2. fix the aspect ratio
  3. glOtho…
#5

Ahhh! you little genius!

How would you focus on one player, aka, zoom in 300% and offset the cam over the player. Dont have to code if you dont want too, Im just trying to get my head round it so that I can learn and not just follow blindly

…as I am typing I can see that my glOrtho is in my init method…so not being updated by player movement…shit.

#6

Hmm. It should be easier to just setup glOrtho with the screen resolution and then translate and scale to the right place.

Just glTranslate to the players coordinates. You might want to center the screen on him too by subtracting half the screen width/height from the translation coordinates. It should be easier to center on the point in between the players (the average of the two players’ positions), and then scale based on how far away they are from each other…

#7

Damm, didnt know I could use scale and translate, I should be able to use the same as I have used in a slick2D game:

g.scale(1.5f, 1.5f);
g.translate(-x + windowWidth / 2 - 120, -y + windowHeight / 2 - 120);

…Im a numpty, thanks for your help, maby all this will make as much scene as it does to you.