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eBookReaderSwitch/thirdparty/freeglut/progs/demos/Fractals/fractals.c

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/* fractals.c */
/*
* Program to draw a fractal by Michael Barnsley's deterministic algorithm.
* Algorithm:
* (1) Define the affine transformations (of the form r(i+1) = A r(i) + b )
* (2) Find the stationary point for each transformation
* (3) To draw:
* - If you are at the lowest level, draw lines connecting all the stationary points
* - If not, call the draw function recursively with each affine transformation applied
*/
/*
* User Commands:
* +,- - increment/decrement number of levels
* PgUp, PgDn - increase/decrease scaling
* Arrow keys - translate viewing section
* r - reset view
* Escape - quit
*/
#include <GL/freeglut.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define FGH_PI 3.14159265358979323846
typedef struct
{
double a00, a01, a10, a11 ; /* Transformation matrix */
double b0, b1 ; /* Constant vector added on */
double statx, staty ; /* Coordinates of the stationary point */
}
AffineTrans ;
/* Number of levels to draw the fractal */
static int num_levels = 4 ;
/* The definition of the fractal */
static int num_trans ;
static AffineTrans *affine ;
/* Flag telling us to keep executing the main loop */
static int continue_in_main_loop = 1;
/* the window title */
char window_title [ 80 ] ;
/* The amount the view is translated and scaled */
double xwin = 0.0, ywin = 0.0 ;
double scale_factor = 1.0 ;
static void draw_level ( int num, double m00, double m01, double m10, double m11, double n0, double n1 )
{
/* Draw a fractal transformed by "M", "N" as passed in */
int i ;
if ( num == 0 )
{
double x0 = m00 * affine[0].statx + m01 * affine[0].staty + n0 ;
double y0 = m10 * affine[0].statx + m11 * affine[0].staty + n1 ;
for ( i = 1; i < num_trans; i++ )
{
double x1 = m00 * affine[i].statx + m01 * affine[i].staty + n0 ;
double y1 = m10 * affine[i].statx + m11 * affine[i].staty + n1 ;
glVertex2d ( x0, y0 ) ;
glVertex2d ( x1, y1 ) ;
x0 = x1 ;
y0 = y1 ;
}
}
else
{
/* Map each affine transformation in the fractal through the one passed in and call "draw_level" */
for ( i = 0; i < num_trans; i++ )
{
draw_level ( num-1, m00*affine[i].a00+m01*affine[i].a10, m00*affine[i].a01+m01*affine[i].a11,
m10*affine[i].a00+m11*affine[i].a10, m10*affine[i].a01+m11*affine[i].a11,
m00*affine[i].b0 +m01*affine[i].b1 + n0, m10*affine[i].b0 +m11*affine[i].b1 + n1 ) ;
}
}
}
static void
Display(void)
{
glClear( GL_COLOR_BUFFER_BIT );
/* the curve */
glPushMatrix();
glScalef(2.5, 2.5, 2.5);
glColor4f(0.0, 0.0, 0.0, 1.0);
glBegin ( GL_LINES ) ;
draw_level ( num_levels, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0 );
glEnd () ;
glPopMatrix();
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
float ar;
glViewport ( 0, 0, width, height ) ;
glMatrixMode ( GL_PROJECTION ) ;
glLoadIdentity();
ar = (float) width / (float) height ;
if( ar > 1 )
glFrustum ( -ar, ar, -1.0, 1.0, 2.0, 100.0 ) ;
else
glFrustum ( -1.0, 1.0, -1/ar, 1/ar, 2.0, 100.0 );
glMatrixMode ( GL_MODELVIEW ) ;
glLoadIdentity () ;
xwin = -1.0 ;
ywin = 0.0 ;
glTranslated ( xwin, ywin, -5.0 ) ;
}
static void
Key(unsigned char key, int x, int y)
{
int need_redisplay = 1;
switch (key) {
case 27: /* Escape key */
continue_in_main_loop = 0 ;
break;
case '+' :
++num_levels ;
break ;
case '-' :
if ( num_levels > 0 )
--num_levels ;
break ;
case 'r' : case 'R' :
glMatrixMode ( GL_MODELVIEW ) ;
glLoadIdentity();
xwin = -1.0 ;
ywin = 0.0 ;
glTranslated ( xwin, ywin, -5.0 ) ;
break ;
default:
need_redisplay = 0;
break;
}
if (need_redisplay)
glutPostRedisplay();
}
static void
Special(int key, int x, int y)
{
int need_redisplay = 1;
switch (key) {
case GLUT_KEY_UP :
glMatrixMode ( GL_MODELVIEW ) ;
ywin += 0.1 * scale_factor ;
glTranslated ( 0.0, 0.1 * scale_factor, 0.0 ) ;
break ;
case GLUT_KEY_DOWN :
glMatrixMode ( GL_MODELVIEW ) ;
ywin -= 0.1 * scale_factor ;
glTranslated ( 0.0, -0.1 * scale_factor, 0.0 ) ;
break ;
case GLUT_KEY_LEFT :
glMatrixMode ( GL_MODELVIEW ) ;
xwin -= 0.1 * scale_factor ;
glTranslated ( -0.1 * scale_factor, 0.0, 0.0 ) ;
break ;
case GLUT_KEY_RIGHT :
glMatrixMode ( GL_MODELVIEW ) ;
xwin += 0.1 * scale_factor ;
glTranslated ( 0.1 * scale_factor, 0.0, 0.0 ) ;
break ;
case GLUT_KEY_PAGE_UP :
glMatrixMode ( GL_MODELVIEW ) ;
glTranslated ( -xwin, -ywin, 0.0 ) ;
glScaled ( 1.25, 1.25, 1.25 ) ;
glTranslated ( xwin, ywin, 0.0 ) ;
scale_factor *= 0.8 ;
break ;
case GLUT_KEY_PAGE_DOWN :
glMatrixMode ( GL_MODELVIEW ) ;
glTranslated ( -xwin, -ywin, 0.0 ) ;
glScaled ( 0.8, 0.8, 0.8 ) ;
glTranslated ( xwin, ywin, 0.0 ) ;
scale_factor *= 1.25 ;
break ;
default:
need_redisplay = 0;
break;
}
if (need_redisplay)
glutPostRedisplay();
}
static void
checkedFGets ( char *s, int size, FILE *stream )
{
if ( fgets ( s, size, stream ) == NULL ) {
fprintf ( stderr, "fgets failed\n");
exit ( EXIT_FAILURE );
}
}
void readConfigFile ( char *fnme )
{
FILE *fptr = fopen ( fnme, "rt" ) ;
int i ;
char inputline [ 256 ] ;
if ( fptr )
{
/* Read a header line */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
/* Read a comment line */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
/* Read the window title */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
/* We assume here that this line will not exceed 79 characters plus a
newline (window_title is 80 characters long). That'll cause a buffer
overflow. For a simple program like this, though, we're letting it
slide!
*/
sscanf ( inputline, "%[a-zA-Z0-9!@#$%^&*()+=/\\_-\" ]", window_title ) ;
/* Read a comment line */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
/* Read the number of affine transformations */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
sscanf ( inputline, "%d", &num_trans ) ;
affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
/* Read a comment line */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
for ( i = 0; i < num_trans; i++ )
{
/* Read an affine transformation definition */
checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
sscanf ( inputline, "%lf %lf %lf %lf %lf %lf", &affine[i].a00, &affine[i].a01,
&affine[i].a10, &affine[i].a11, &affine[i].b0, &affine[i].b1 ) ;
}
}
else /* No data file, set a default */
{
printf ( "ERROR opening file <%s>\n", fnme ) ;
strcpy ( window_title, "Koch Snowflake" ) ;
num_trans = 4 ;
affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
affine[0].a00 = 1/3. ; affine[0].a01 = 0.00 ; affine[0].a10 = 0.00 ; affine[0].a11 = 1/3. ;
affine[0].b0 = 0.0 ; affine[0].b1 = 0.0 ;
affine[1].a00 = 1/6. ; affine[1].a01 = -1/3.*sin(FGH_PI/3.) ; affine[1].a10 = 1/3.*sin(FGH_PI/3.) ; affine[1].a11 = 1/6. ;
affine[1].b0 = 1/3. ; affine[1].b1 = 0.0 ;
affine[2].a00 = 1/6. ; affine[2].a01 = -1/3.*sin(-FGH_PI/3.) ; affine[2].a10 = 1/3.*sin(-FGH_PI/3.) ; affine[2].a11 = 1/6. ;
affine[2].b0 = 0.5 ; affine[2].b1 = sqrt(3)/6. ;
affine[3].a00 = 1/3. ; affine[3].a01 = 0.00 ; affine[3].a10 = 0.00 ; affine[3].a11 = 1/3. ;
affine[3].b0 = 2/3. ; affine[3].b1 = 0.0 ;
}
for ( i = 0; i < num_trans; i++ )
{
double m00, m01, m10, m11 ; /* Matrix "I" minus "A" */
double determ ; /* Determinant of this matrix */
/* Calculate the stationary point */
m00 = 1.0 - affine[i].a00 ;
m01 = - affine[i].a01 ;
m10 = - affine[i].a10 ;
m11 = 1.0 - affine[i].a11 ;
determ = m00 * m11 - m01 * m10 ;
if ( fabs ( determ ) > 1.e-6 )
{
affine[i].statx = ( m11 * affine[i].b0 - m01 * affine[i].b1 ) / determ ;
affine[i].staty = ( -m10 * affine[i].b0 + m00 * affine[i].b1 ) / determ ;
}
else
affine[i].statx = affine[i].staty = 0.0 ;
}
}
int
main(int argc, char *argv[])
{
glutInitWindowSize(500, 250);
glutInitWindowPosition ( 140, 140 );
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE );
glutInit(&argc, argv);
if ( argc > 1 )
readConfigFile ( argv[1] ) ;
else
readConfigFile ( "fractals.dat" ) ;
glutCreateWindow( window_title );
glClearColor(1.0, 1.0, 1.0, 1.0);
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutSpecialFunc(Special);
glutDisplayFunc(Display);
#ifdef WIN32
#endif
while ( continue_in_main_loop )
glutMainLoopEvent();
printf ( "Back from the 'freeglut' main loop\n" ) ;
return 0; /* ANSI C requires main to return int. */
}
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