Program: 1343
Project: 1343
Buggy source:
public void render(){
  glClearColor(world.getDaylightColor().x,world.getDaylightColor().y,world.getDaylightColor().z,1.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();
  player.render();
  world.render();
  Vector3f blockPosition=player.calcViewBlockPosition();
  int bpX=(int)blockPosition.x;
  int bpY=(int)blockPosition.y;
  int bpZ=(int)blockPosition.z;
  glColor3f(1.0f,0.0f,0.0f);
  glLineWidth(4.0f);
  glBegin(GL_LINES);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
  glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
  glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
  glEnd();
}

Fixed version (ground truth):
public void render(){
  glClearColor(world.getDaylightColor().x,world.getDaylightColor().y,world.getDaylightColor().z,1.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();
  player.render();
  world.render();
  Vector3f blockPosition=player.calcViewBlockPosition();
  if (blockPosition != null) {
    int bpX=(int)blockPosition.x;
    int bpY=(int)blockPosition.y;
    int bpZ=(int)blockPosition.z;
    glColor3f(1.0f,0.0f,0.0f);
    glLineWidth(4.0f);
    glBegin(GL_LINES);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ - 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ - 0.5f);
    glVertex3f(bpX - 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX - 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY - 0.5f,bpZ + 0.5f);
    glVertex3f(bpX + 0.5f,bpY + 0.5f,bpZ + 0.5f);
    glEnd();
  }
}