create a rotation camera in processing

float camx = width / 2.0;
float camy = height / 2.0;
float camz = (height / 2.0) / tan(PI * 30.0 / 180.0);
float camangle = 0;

void setup() {
  size(640, 360, P3D);
}

void draw() {
  background(0);
  float camangle = map(mouseX, 0, width, 0, PI * 2);
  float camy = map(mouseY, 0, height, 200, 100);
  camera(camx, camy, camz, camx + cos(camangle), camy, camz + sin(camangle), 0, 1, 0);

  // Draw the box
  noStroke();
  fill(255);
  box(50);
}