Mandelbrot Rendering Graphics

hamster

Hi All,

I recently dug up an ancient college C programming assignment of mine. This simply drew a Mandelbrot on screen. I think this was done on FreeBSD ver? back in 1995. I'm trying to render this on my copy of RedHat. Now, I haven't touch c in awhile but the below is easy enough except for the 4 graphical operations below:

These graphical operations were provided to us students in manlib.h library file which contained the following 4 functions:
makewindow(), drawpixel(), keepwindow() and getmouse(). I never saw the internally working of these 4 functions.

#define COLORBLACK 0 /*the standard value for black*/
#define NRCOLORS 21 /*nr colors available, from 0 to NRCOLORS-1 */


/*Create a window with pixel dimensions (size * size). Its top lefthand corner is (0,0) and bottom right is (size,size).
*/
void makewindow(unsigned int size);

/*
* draw a pixel, in the window created by makewindow, at point
* (x,y) with colour given by color.
* note that color must be in range BLACK to NRCOLORS-1
*/
void drawpixel(unsigned int x, unsigned int y, int color);

/*
* Keep the window displayed until a mouse button is `clicked'
* in the window.
*/
void keepwindow ();



/*
* Get the next event from the mouse. Function returns values
* in the range 1..3 ( left, middle and right mouse button pressed).
* (x,y) gives the coordinates of the pointer when the button
* was pressed.
*/
int getmouse(unsigned int *x, unsigned int *y);





As I said, I never saw the internally working of these 4 functions but I would love to replace them with my own but I haven't a clue under c for graphics. I have redhat 9 with the gcc compiler working. How difficult would it be to replace the 4 operations above? Are there closely native operations in c that would do the above? ie
i) getting the mouse co-ordinates
ii) keeping the window. I don't understand this one. Basically a terminal-like window holds the image until it is clicked closed
iii) drawpixel... is there a draw command?
iv) oh oh... making a window... I think this involves creating initially an empty terminal-like window to hold the rendering imagine.

As you can see my experience in graphics in c was limited. Any help would be greatly appreciated.



The original code example, using "manlib.h" for those hidden graphical operations that I don't have.



/*
* mandel.c
*
* A program to i) Plot the Mandelbrot set in the Complex Plane
* ii) Allow the functionality of a scaleable Fractal
* iii) Allow user to set Interactive Zoom Rate
*
* Date: 7/12/95
*
*/

#include <stdio.h>
#include "manlib.h"

#define WINSIZE 250 /* Set window size to 250 x 250 pixels */
#define INFINITY 100 /* Set infinity to beyond 100 iterations */

double acorn,bcorn,size, /* Co-ordinates a and b, size S */
ca,cb, /* 1st and 2nd part of Complex Number */
zx,zy, /* x and y component of Complex Number */
xtemp, /* zx is computed in temporary value */
mag, /* User can change Zoom Rate */
temp=(2.5/WINSIZE), /* Conversion depending on WINSIZE */
compval_x,compval_y; /* Complex conversion of x,y co-ords */

int j,k, /* Screen co-ordinates j,k */
count, /* Number of iterations */
colorfactor; /* Colour designer */
unsigned int button=1, /* Reads a value from a mouse button */
x,y; /* Reads mouse click co-ordinates */

void print_instructions() /* Program objectives and operations */
{
printf("\n%s"," Welcome to MANDELBROT BROWSER.");
printf("\n\n%s","A program to plot the Mandelbrot set in the complex");
printf("\n%s","plane. The top-left hand corner of the plane is given");
printf("\n%s","by complex number (a+bi).");
printf("\n%s","The size of the plane is given by non-zero S.");
printf("\n\n%s","Input the real numbers a b and S");
printf("\n%s","(Try -2 -1.25 2.5 ): ");
}

void initialization() /* Set up colours, Ask user for co-ords, Zoom rate */
{
colorfactor=(INFINITY/(NRCOLORS-1)); /* Defines colour range */
scanf("%lf %lf %lf",&acorn,&bcorn,&size); /* Read in a,b and size */
printf("\n%s","Please enter interactive Zoom Factor (from 2 to 20): ");
scanf("%lf",&mag); /* Ask user for Zoom Rate */
while ((mag<2) || (mag>20)) /* If user enters a value outside range */
{
printf("\n%s","Sorry enter a Zoom rate between 2 to 20 : ");
scanf("%lf",&mag);
}
}

void draw_mandelbrot() /* The Mandelbrot designer engine */
{
for (j=1; j<=WINSIZE; j++) /* Draw (1,*)..(2,*)..etc */
{
for (k=1; k<=WINSIZE; k++) /* Draw (*,1)..(*,2)..etc */
{
count=0;
ca=acorn+((j*size)/WINSIZE); /* 1st part of Complex Number */
cb=bcorn+((k*size)/WINSIZE); /* 2nd part of Complex Number */
zx=0; /* Initialize x component */
zy=0; /* Initialize y component */

while ((count<INFINITY) && ((zx*zx)+(zy*zy)) <=4 )
{
count++; /* Next Iteration */
xtemp=(zx*zx)-(zy*zy); /* X part is computed in temp */
zy=(2*zx*zy)+cb; /* RE and IM parts are added */
zx=xtemp+ca; /* to zy and zx in that order */
}

if (count==INFINITY)
drawpixel (j,k,0); /* Draw black pixels in lake */
else /* else draw non-black pixel */
drawpixel (j,k,((count/colorfactor)+1));

} /* For K */
} /* For J */
} /* Draw_mandelbrot */

void print_options() /* User mouse options */
{
printf("\a\n%s","Finished plotting Mandelbrot set.");
printf("\n\n%s","Click middle mouse button to exit.");
printf("\n%s","Click left mouse button at a region");
printf("\n%s","to enlarge it.");
printf("\n%s","Click right mouse button at a region");
printf("\n%s\n","to zoom out from it.");
} /* print_options */

void zoom() /* Zoom in/out with new acorn and bcorn */
{
compval_x=(x*(temp)+acorn); /* Adding on old acorn */
compval_y=(y*(temp)+bcorn); /* Adding on old acorn */
acorn=compval_x-(size/2); /* New acorn, bcorn */
bcorn=compval_y-(size/2);
temp=temp*(1/mag); /* Creates a finer draw mesh */
printf("\a\n%s%lf %s %lf%s %lf\n","Plotting from (",acorn,"+",bcorn,
"i) at size",size);
draw_mandelbrot(); /* Draw new zoomed fractal */
} /* zoom */

void magnify_mandelbrot()
{
while (button!=2) /* Terminate with middle mouse button */
{
button=getmouse(&x,&y); /* Records mouse clicked */
if (button==1) /* If left mouse button is clicked */
{
size=(size/mag); /* Zoom in Fractal by a factor of mag */
zoom();
}
if (button==3) /* If right mouse button is clicked */
{
size=(size*mag); /* Zoom out Fractal by a factor of mag */
zoom();
}
}
} /* Magnify_mandelbrot */

void main()
{
print_instructions(); /* Introduction */
initialization(); /* Set up Initial parameters */
makewindow(WINSIZE); /* Draws window at WINSIZE */
draw_mandelbrot(); /* Draw initial Mandelbrot */
print_options(); /* User decides next move using mouse */
magnify_mandelbrot(); /* Zoom in/out or quit Mandelbrot */

printf("\n%s\n","Bye! Thanks for using Mandelbrot Browser.");
}

Insectman2000

Originally posted by hamster
Hi All,


/*
* mandel.c
*
* A program to i) Plot the Mandelbrot set in the Complex Plane
* ii) Allow the functionality of a scaleable Fractal
* iii) Allow user to set Interactive Zoom Rate
*
* Date: 7/12/95
*
*/

#include <stdio.h>
#include "manlib.h"

#define WINSIZE 250 /* Set window size to 250 x 250 pixels */
#define INFINITY 100 /* Set infinity to beyond 100 iterations */

double acorn,bcorn,size, /* Co-ordinates a and b, size S */
ca,cb, /* 1st and 2nd part of Complex Number */
zx,zy, /* x and y component of Complex Number */
xtemp, /* zx is computed in temporary value */
mag, /* User can change Zoom Rate */
temp=(2.5/WINSIZE), /* Conversion depending on WINSIZE */
compval_x,compval_y; /* Complex conversion of x,y co-ords */

int j,k, /* Screen co-ordinates j,k */
count, /* Number of iterations */
colorfactor; /* Colour designer */
unsigned int button=1, /* Reads a value from a mouse button */
x,y; /* Reads mouse click co-ordinates */

void print_instructions() /* Program objectives and operations */
{
printf("\n%s"," Welcome to MANDELBROT BROWSER.");
printf("\n\n%s","A program to plot the Mandelbrot set in the complex");
printf("\n%s","plane. The top-left hand corner of the plane is given");
printf("\n%s","by complex number (a+bi).");
printf("\n%s","The size of the plane is given by non-zero S.");
printf("\n\n%s","Input the real numbers a b and S");
printf("\n%s","(Try -2 -1.25 2.5 ): ");
}

void initialization() /* Set up colours, Ask user for co-ords, Zoom rate */
{
colorfactor=(INFINITY/(NRCOLORS-1)); /* Defines colour range */
scanf("%lf %lf %lf",&acorn,&bcorn,&size); /* Read in a,b and size */
printf("\n%s","Please enter interactive Zoom Factor (from 2 to 20): ");
scanf("%lf",&mag); /* Ask user for Zoom Rate */
while ((mag<2) || (mag>20)) /* If user enters a value outside range */
{
printf("\n%s","Sorry enter a Zoom rate between 2 to 20 : ");
scanf("%lf",&mag);
}
}

void draw_mandelbrot() /* The Mandelbrot designer engine */
{
for (j=1; j<=WINSIZE; j++) /* Draw (1,*)..(2,*)..etc */
{
for (k=1; k<=WINSIZE; k++) /* Draw (*,1)..(*,2)..etc */
{
count=0;
ca=acorn+((j*size)/WINSIZE); /* 1st part of Complex Number */
cb=bcorn+((k*size)/WINSIZE); /* 2nd part of Complex Number */
zx=0; /* Initialize x component */
zy=0; /* Initialize y component */

while ((count<INFINITY) && ((zx*zx)+(zy*zy)) <=4 )
{
count++; /* Next Iteration */
xtemp=(zx*zx)-(zy*zy); /* X part is computed in temp */
zy=(2*zx*zy)+cb; /* RE and IM parts are added */
zx=xtemp+ca; /* to zy and zx in that order */
}

if (count==INFINITY)
drawpixel (j,k,0); /* Draw black pixels in lake */
else /* else draw non-black pixel */
drawpixel (j,k,((count/colorfactor)+1));

} /* For K */
} /* For J */
} /* Draw_mandelbrot */

void print_options() /* User mouse options */
{
printf("\a\n%s","Finished plotting Mandelbrot set.");
printf("\n\n%s","Click middle mouse button to exit.");
printf("\n%s","Click left mouse button at a region");
printf("\n%s","to enlarge it.");
printf("\n%s","Click right mouse button at a region");
printf("\n%s\n","to zoom out from it.");
} /* print_options */

void zoom() /* Zoom in/out with new acorn and bcorn */
{
compval_x=(x*(temp)+acorn); /* Adding on old acorn */
compval_y=(y*(temp)+bcorn); /* Adding on old acorn */
acorn=compval_x-(size/2); /* New acorn, bcorn */
bcorn=compval_y-(size/2);
temp=temp*(1/mag); /* Creates a finer draw mesh */
printf("\a\n%s%lf %s %lf%s %lf\n","Plotting from (",acorn,"+",bcorn,
"i) at size",size);
draw_mandelbrot(); /* Draw new zoomed fractal */
} /* zoom */

void magnify_mandelbrot()
{
while (button!=2) /* Terminate with middle mouse button */
{
button=getmouse(&x,&y); /* Records mouse clicked */
if (button==1) /* If left mouse button is clicked */
{
size=(size/mag); /* Zoom in Fractal by a factor of mag */
zoom();
}
if (button==3) /* If right mouse button is clicked */
{
size=(size*mag); /* Zoom out Fractal by a factor of mag */
zoom();
}
}
} /* Magnify_mandelbrot */

void main()
{
print_instructions(); /* Introduction */
initialization(); /* Set up Initial parameters */
makewindow(WINSIZE); /* Draws window at WINSIZE */
draw_mandelbrot(); /* Draw initial Mandelbrot */
print_options(); /* User decides next move using mouse */
magnify_mandelbrot(); /* Zoom in/out or quit Mandelbrot */

printf("\n%s\n","Bye! Thanks for using Mandelbrot Browser.");
}

Skyclad

Try writing it in Prolog. Thats the way of the future I hear. Or openGL, but that one tend to wreck the head too much.

Dave

Talliesin

Insectman2000 wins the contest to find the stupidest and most pointless post ever to the programming board.

Prize is a lifetime ban.

Congratulations.