Opengl add a new object in each click?

Question

void onClick(int button, int state, int x, int y) {
  if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
    drawHouse(x,y);
}

I have a problem about opengl onclick function. I drawed an object(primitive house) and i want to display it when i click on the mouse. How can i do this?

My teacher gave this command: "Add a new object, defined in the first part, after the user presses mouse left button. Each click adds a new object at the position of click. Maximum 10 objects can be created on the screen. Then, after each click a new object should replace the first object."

Answer 1

One possible soultion would be to store the mouse positions in an array with length of 10. Each click adds a new entry to the array. If the array is full, the entries get overwritten:

#define MAX_OBJ 10

int pos_x[MAX_OBJ], pos_y[MAX_OBJ];
int count  = 0;
int next_i = 0;

void onClick(int button, int state, int x, int y)
{
    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
    {
       pos_x[next_i] = x;
       pos_y[next_i] = y;
       next_i ++;
       if ( next_i == MAX_OBJ ) next_i = 0;
       if ( count < MAX_OBJ )   count ++;
    }
}

In the main loop you can draw the objects to the known positions:

for( int i = 0; i < MAX_OBJ; ++ i )
    drawHouse( pos_x[i], pos_y[i] );