Le source: ExempleBresenhamCercle.cpp
/* Auteur: Nicolas JANEY */
/* nicolas.janey@univ-fcomte.fr */
/* Mars 2002 */
/* Trace de cercles */
/* par l'algorithme de Bresenham */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <stdarg.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include "ModuleCouleurs.h"
#include "ModuleMenus.h"
#include "ModuleFont.h"
#include "ModuleFleche.h"
#include "ModuleReshape.h"
static int aff;
static int yy;
static int f1;
static int f2;
static char buffer[2000];
static int pos;
static float r = 20.0F;
void dessineQuadrillage(void) {
float i;
glColor4fv(couleurGrisMoyen()) ;
glBegin(GL_LINES);
for ( i = -1.0 ; i < 24 ; i++ ) {
glVertex2d(-1.0,i);
glVertex2d(17.0,i); }
for ( i = -1.0 ; i < 18 ; i++ ) {
glVertex2d(i,-1.0);
glVertex2d(i,23.0); }
glEnd() ;
glPushMatrix();
glTranslatef(-0.5F,0.5F,0.0F);
flecheEnVolume(17.2F,0.0F,0.0F,0.35F,1.4F,0.1F);
glPopMatrix();
glPushMatrix();
glTranslatef(0.5F,-0.5F,0.0F);
flecheEnVolume(0.0F,23.2F,0.0F,0.35F,1.4F,0.1F);
glPopMatrix();
}
void arc(float r) {
glLineWidth(3.0);
glColor4fv(couleurBleu()) ;
glBegin(GL_LINE_STRIP) ;
for ( int i = 0 ; i <= 45 ; i++ ) {
float angle = i * 3.14159F / 180 ;
float x = (float) (r*cos(angle)+0.5F) ;
float y = (float) (r*sin(angle)+0.5F) ;
glVertex2f(y,x) ; }
glEnd() ;
glLineWidth(1.0);
}
void pixel(int x,int y,float *c) {
glColor4fv(c) ;
glBegin(GL_QUADS) ;
glVertex2f(x,y) ;
glVertex2f(x,y+1) ;
glVertex2f(x+1,y+1) ;
glVertex2f(x+1,y) ;
glEnd() ;
}
void arcDiscret(float *c,float r) {
int x,y,d ;
x = 0 ;
y =(int) r ;
d =(int) (1 - r) ;
pixel(x,y,c) ;
while ( y > x ) {
if ( d < 0 )
d += 2 * x + 3 ;
else {
d += 2 * (x - y) + 5 ;
y-- ; }
x++ ;
pixel(x,y,c) ; }
}
void arcIncomplet(float *c,float r,int max) {
int x,y,d ;
x = 0 ;
y =(int) r ;
d =(int) (1 - r) ;
pixel(x,y,c) ;
int cpt = 0;
while ( ( y > x ) && ( cpt < max ) ) {
cpt++;
if ( d < 0 )
d += 2 * x + 3 ;
else {
d += 2 * (x - y) + 5 ;
y-- ; }
x++ ;
pixel(x,y,c) ; }
}
void output(float x,char *format,...) {
va_list args;
va_start(args,format);
vsprintf(buffer,format,args);
va_end(args);
placeFontCursor(x,-pos*20.0F+10,0.0F) ;
simpleBitmapOutput(1,REGULAR8x13,buffer) ;
}
void newLine() {
pos += 1;
}
void arcIncompletTexte(float r,int max) {
pos = 1;
glColor4fv(couleurGrisMoyen());
glBegin(GL_LINES);
glVertex2f(205.0F,-5.0F);
glVertex2f(205.0F,-320.0F);
glVertex2f(245.0F,-5.0F);
glVertex2f(245.0F,-320.0F);
glVertex2f(5.0F,-22.0F);
glVertex2f(345.0F,-22.0F);
glEnd();
glColor4fv(couleurBlanc());
int x,y,d ;
x = 0 ;
y =(int) r ;
d =(int) (1 - r) ;
output(105.0F,"d") ;
output(225.0F,"x") ;
output(295.0F,"y") ;
newLine();
output(105.0F,"%d",d) ;
output(225.0F,"%d",x) ;
output(295.0F,"%d",y) ;
newLine();
int cpt = 0;
while ( ( y > x ) && ( cpt < max ) ) {
cpt++;
int old = d;
if ( d < 0 ) {
d += 2 * x + 3 ;
output(105.0F,"%d+2*%d+3 -> %d",old,x,d) ;
output(295.0F,"%d",y) ; }
else {
d += 2 * (x - y) + 5 ;
output(105.0F,"%d+2*(%d-%d)+5 -> %d",old,x,y,d) ;
y-- ;
output(295.0F,"%d -> %2d",y+1,y) ; }
x++ ;
output(225.0F,"%d",x) ;
newLine(); }
}
void display() {
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glPushMatrix();
dessineQuadrillage();
glColor4fv(couleurGrisMoyen());
glLineWidth(3.0);
glBegin(GL_LINES);
glVertex2f(0.5F,0.5F);
glVertex2f(16.5F,16.5F);
glEnd();
glLineWidth(1.0);
switch (aff) {
case 0 : arc(r) ;
break ;
case 1 : arcDiscret(couleurRouge(0.5F),r) ;
arc(r) ;
break ;
case 2 : arcIncomplet(couleurRouge(0.5F),r,yy) ;
arc(r) ; }
glutPostWindowRedisplay(f2);
glPopMatrix();
glFlush();
glutSwapBuffers() ;
}
void myinit() {
glEnable(GL_ALPHA_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0.8F,0.8F,0.8F,1.0F);
setAlignement(CENTER);
}
void key(unsigned char key,int x,int y) {
switch ( key ) {
case 32 : yy = (yy+1)%15 ;
glutPostWindowRedisplay(f1);
break;
case 0x0D : yy = 0 ;
aff = (aff+1)%3 ;
glutPostWindowRedisplay(f1);
break;
case 0x1B : exit(0) ;
break; }
}
void display2(void) {
glClearColor(0.0F,0.0F,0.0F,1.0F) ;
glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
glPushMatrix();
switch (aff) {
case 2 : arcIncompletTexte(r,yy) ; }
glPopMatrix();
glFlush();
glutSwapBuffers();
}
void reshape2(int w,int h) {
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,w,-h,0,-1.0,1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
int main(int argc,char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
glutInitWindowSize(270,360);
glutInitWindowPosition(50,10);
f1 = glutCreateWindow("Cercle par l'algorithme de Bresenham");
myinit();
creationMenuBasique();
setParametresOrthoBasique(-1.5,17.5,-1.2,17.8,-40.0,40.0);
glutReshapeFunc(reshapeOrthoBasique);
glutKeyboardFunc(key);
glutDisplayFunc(display);
glutInitWindowSize(350,325);
glutInitWindowPosition(350,10);
glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
f2 = glutCreateWindow("Valeurs");
creationMenuBasique();
glutDisplayFunc(display2);
glutReshapeFunc(reshape2);
glutKeyboardFunc(key);
glutMainLoop();
return(0);
}
RETOUR