GameMaker Zooming out problems

[TulioHenry]

I've started a project of a local multiplayer shooter, where the cameras will work like this:
- 1 player : the camera will only focus the player , without zoom
- 2 player: the camera will calculate a zoom and it will add to the camera size

but i have a problem, when the camera add the zoom out the sprites start adding pixel and stretching, losing the aspect ratio

#macros
GAMEWIDTH = 640;
GAMEHEIGHT = 360;


heres the code:

Game object -> i use to control the game in general
//create

windowscale = 2;

window_set_size(GAMEWIDTH*windowscale,GAMEHEIGHT*windowscale);
display_set_gui_size(GAMEWIDTH*windowscale,GAMEHEIGHT*windowscale);
alarm[0] = 1;

surface_resize(application_surface,GAMEWIDTH*windowscale,GAMEHEIGHT*windowscale);

oCAMERA object -> the actual camera code
//Create

following = oparPlayer;
zoom = 2;
spd = 0.1; //the speed of interpolation

//Step

gameW = GAMEWIDTH / 2 * zoom;
gameH = GAMEHEIGHT / 2 * zoom;

camera_set_view_size(CAM, gameW, gameH);

var player_num = instance_number(oparPlayer);
var players = ds_grid_create(1,1);
ds_grid_resize(players,1,player_num);

var i = 0;
with(oparPlayer){
    players[# 0,i] = id;
    i++
}

switch(player_num){
   case 1 : //single player
        if(instance_exists(following)){
            var xx = clamp(following.x - gameW/2, 0, room_width - gameW);
            var yy = clamp(following.y - gameH/2, 0, room_height - gameH);

            var cx = camera_get_view_x(CAM);
            var cy = camera_get_view_y(CAM);    

            camera_set_view_pos(CAM,
                             lerp(cx,xx,spd),
                             lerp(cy,yy,spd) );
                     

        }
 
    break;

    case 2: //2 players

       var multi_xx = mean(players[# 0,0].x,players[# 0,1].x);
       var multi_yy = mean(players[# 0,0].y,players[# 0,1].y);


       var xx1 = clamp(multi_xx - gameW/2, 0, room_width - gameW);
       var yy1 = clamp(multi_yy - gameH/2, 0, room_height - gameH);

       var distance_x = abs(players[# 0,0].x - players[# 0,1].x);
       var distance_y = abs(players[# 0,0].y - players[# 0,1].y);

       zoom = clamp(lerp(zoom, sqrt(sqr(distance_x) + sqr(distance_y) ) / 100, spd- 0.05), 3, 4)


        var cx = camera_get_view_x(CAM);
        var cy = camera_get_view_y(CAM);


        camera_set_view_pos(CAM,
                            lerp(cx,xx1,spd),
                            lerp(cy,yy1,spd) );

    break;

    }

My inspiration to the camera code was the camera of the duck game.


here is when the zoom is 1:


and when zoom is 4:


im just showing this zoom level, but almost any zoom it starts to add more pixels

 

[TsukaYuriko]

Please post screenshots of the game at default resolution and when zoomed - this may help us identify what's going on and/or what's wrong.

 

[Anders__oo__]

How do you implement the zoom?