house.c

The art and science of c_source code!

/*
 * File: house.c
 * -------------
 * This program draws a simple frame house.
 */

#include <stdio.h>

#include "genlib.h"
#include "graphics.h"

/*
 * Constants
 * ---------
 * The following constants control the sizes of the
 * various elements in the display.
 */

#define HouseHeight         2.0
#define HouseWidth          3.0
#define AtticHeight         0.7

#define DoorWidth           0.4
#define DoorHeight          0.7
#define DoorknobRadius      0.03
#define DoorknobInset       0.07

#define PaneHeight          0.25
#define PaneWidth           0.2

#define FirstFloorWindows   0.3
#define SecondFloorWindows  1.25

/* Function prototypes */

void DrawHouse(double x, double y);
void DrawOutline(double x, double y);
void DrawWindows(double x, double y);
void DrawDoor(double x, double y);
void DrawBox(double x, double y, double width, double height);
void DrawTriangle(double x, double y, double base, double height);
void DrawCenteredCircle(double x, double y, double r);
void DrawGrid(double x, double y, double width, double height,
              int columns, int rows);

/* Main program */

main()
{
    double cx, cy;

    InitGraphics();
    cx = GetWindowWidth() / 2;
    cy = GetWindowHeight() / 2;
    DrawHouse(cx - HouseWidth / 2,
              cy - (HouseHeight + AtticHeight) / 2);
}

/*
 * Function: DrawHouse
 * Usage: DrawHouse(x, y);
 * -----------------------
 * This function draws a house diagram with the lower left corner
 * at (x, y).  This level of the function merely divides up
 * the work.
 */

void DrawHouse(double x, double y)
{
    DrawOutline(x, y);
    DrawDoor(x + (HouseWidth - DoorWidth) / 2, y);
    DrawWindows(x, y);
}

/*
 * Function: DrawOutline
 * Usage: DrawOutline(x, y);
 * -------------------------
 * This function draws the outline for the house, using (x, y)
 * as the origin.  The outline consists of a box with a triangle
 * on top.
 */

void DrawOutline(double x, double y)
{
    DrawBox(x, y, HouseWidth, HouseHeight);
    DrawTriangle(x, y + HouseHeight, HouseWidth, AtticHeight);
}

/*
 * Function: DrawDoor
 * Usage: DrawDoor(x, y);
 * ----------------------
 * This function draws a door, with its doorknob.  As usual,
 * (x, y) specifies the lower left corner of the door.
 */

void DrawDoor(double x, double y)
{
    DrawBox(x, y, DoorWidth, DoorHeight);
    DrawCenteredCircle(x + DoorWidth - DoorknobInset,
                       y + DoorHeight / 2, DoorknobRadius);
}

/*
 * Function: DrawWindows
 * Usage: DrawWindows(x, y);
 * -------------------------
 * This function draws all the windows for the house,
 * taking advantage of the fact that the windows are all
 * arranged in two-dimensional grids of equal-sized panes.
 * By calling the function DrawGrid, this implementation
 * can create all of the window structures using a single
 * tool.
 */

void DrawWindows(double x, double y)
{
    double xleft, xright;

    xleft = x + HouseWidth * 0.25;
    xright = x + HouseWidth * 0.75;
    DrawGrid(xleft - PaneWidth * 1.5, y + FirstFloorWindows,
             PaneWidth, PaneHeight, 3, 2);
    DrawGrid(xright - PaneWidth * 1.5, y + FirstFloorWindows,
             PaneWidth, PaneHeight, 3, 2);
    DrawGrid(xleft - PaneWidth, y + SecondFloorWindows,
             PaneWidth, PaneHeight, 2, 2);
    DrawGrid(xright - PaneWidth, y + SecondFloorWindows,
             PaneWidth, PaneHeight, 2, 2);
}

/*
 * Function: DrawBox
 * Usage: DrawBox(x, y, width, height)
 * -----------------------------------
 * This function draws a rectangle of the given width and
 * height with its lower left corner at (x, y).
 */

void DrawBox(double x, double y, double width, double height)
{
    MovePen(x, y);
    DrawLine(0, height);
    DrawLine(width, 0);
    DrawLine(0, -height);
    DrawLine(-width, 0);
}

/*
 * Function: DrawTriangle
 * Usage: DrawTriangle(x, y, base, height)
 * ---------------------------------------
 * This function draws an isosceles triangle (i.e., one with
 * two equal sides) with a horizontal base.  The coordinate of
 * the left endpoint of the base is (x, y), and the triangle
 * has the indicated base length and height.  If height is
 * positive, the triangle points upward.  If height is negative,
 * the triangle points downward.
 */

void DrawTriangle(double x, double y, double base, double height)
{
    MovePen(x, y);
    DrawLine(base, 0);
    DrawLine(-base / 2, height);
    DrawLine(-base / 2, -height);
}

/*
 * Function: DrawCenteredCircle
 * Usage: DrawCenteredCircle(x, y, r);
 * -----------------------------------
 * This function draws a circle of radius r with its
 * center at (x, y).
 */

void DrawCenteredCircle(double x, double y, double r)
{
    MovePen(x + r, y);
    DrawArc(r, 0, 360);
}

/*
 * Function: DrawGrid
 * Usage: DrawGrid(x, y, width, height, columns, rows);
 * ----------------------------------------------------
 * DrawGrid draws rectangles arranged in a two-dimensional
 * grid.  As always, (x, y) specifies the lower left corner
 * of the figure.
 */

void DrawGrid(double x, double y, double width, double height,
              int columns, int rows)
{
    int i, j;

    for (i = 0; i < columns; i++) {
        for (j = 0; j < rows; j++) {
            DrawBox(x + i * width, y + j * height,
                    width, height);
        }
    }
}