カメラ座標系とスクリーン座標系の関係 Processing

int x,y,z;

void setup(){

size(640,480,P3D);

camera(width/2.0, height/2.0, (height/2.0) / tan(PI*60.0 / 360.0), width/2.0, height/2.0, 0, 0, 1, 0);

noFill();

}

void draw(){

background(255,255,255);

translate(x,y,z);

box(10);

if(keyPressed){

switch(keyCode){

case UP:y--;break;

case DOWN:y++;break;

case LEFT:x--;break;

case RIGHT:x++;break;

case SHIFT:z--;break;

}

if(key==' ')z++;

}

println("(x,y,z)=("+x+","+y+","+z+")");

println((height/2.0) / tan(PI*60.0 / 360.0));

}