// File: ztest.cxx
// This is a simple test program for the zbuffer class
#include <iostream>
#include <winbgim.h>
#include "zbuffer.h"
using namespace std;

const int WIDTH=300;
const int HEIGHT=400;
const int EYE_DISTANCE=400;

void draw_design(ZBuffer& zb, double angle);
// This function draws a little design on the currently active page
// using the ZBuffer zb to control which pixels are seen.  The
// Design consists of a yellow rectangle with a red line going
// through its center.  The angle parameter determines the angle
// of the line in the x-z plane.  The ends of the line have
// cyan and green spheres.

void swap_screens( );
// This function swaps the active and visual pages, which must be
// pages number 1 and 2.

int main( )
{
    double angle=0;
    ZBuffer zb(WIDTH, HEIGHT, EYE_DISTANCE);
    
    initwindow(WIDTH, HEIGHT);
    setactivepage(1);
    setvisualpage(2);
    
    while (!kbhit( ))
    {
	clearviewport( ); // Clear the screen
	zb.clear( );      // And clear the zbuffer
	draw_design(zb, angle);
	swap_screens( );
	angle += 0.0314159;
    }
    
    getch( );

    return 0;
}

void draw_design(ZBuffer& zb, double angle)
{
    int i, j;
    double x1, z1, x2, y2, z2;

    // Compute x and z coordinates of a line:
    x2 = WIDTH/2*cos(angle);
    z1 = WIDTH/2*sin(2*angle);
    x1 = WIDTH/2*cos(angle+3.14159);
    y2 = HEIGHT/2*cos(angle);
    z2 = WIDTH/2*sin(2*angle+3.14159);

    // Draw a YELLOW rectangle, a RED line and a GREEN sphere:
    for (i = -30; i < 30; i++)
	for (j = 0; j < 30; j++)
	    zb.point(i, j, 0, YELLOW);
    zb.line(x1, 15, z1, x2, y2, z2, RED);
    zb.sphere(x1, 15, z1, 20, CYAN);
    zb.sphere(x2, y2, z2, 20, GREEN);
    zb.line(0, -100, 0, 0, 100, 0, WHITE);
}

void swap_screens( )
{
    if (getactivepage() == 1)
    {
	setactivepage(2);
	setvisualpage(1);
    }
    else
    {
	setactivepage(1);
	setvisualpage(2);
    }
}