L'extrémité initiale est dessinée en rouge. L'autre extrémité est de couleur verte.
Le source : Exam-TD1-2004-2005-Exo2.cpp
/* Auteur: Nicolas JANEY */
/* nicolas.janey@univ-fcomte.fr */
/* Novembre 2004 */
/* Algorithme de Bresenham */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include "ModuleCouleurs.h"
#include "ModuleMenus.h"
#include "ModuleFont.h"
#include "ModuleReshape.h"
struct point {
int x ;
int y ; } ;
struct segment {
point pi ;
point pf ; } ;
struct rectangle {
point sg ;
point id ; } ;
static int aff = 0 ;
static int pt = 0 ;
static segment s[8] = { { 2,10,27,19 },
{ 5, 9,28, 4 },
{ 25, 3, 8,16 },
{ 28,13, 4, 4 },
{ 12, 3,17,19 },
{ 13,18,19, 4 },
{ 18, 3,15,16 },
{ 18,18,14, 4 } } ;
static int f1;
static int f2;
void pixel(int x,int y,float *c) {
glColor4fv(c) ;
glBegin(GL_QUADS) ;
glVertex2f(x-1.0F,y-1.0F) ;
glVertex2f(x-1.0F,y) ;
glVertex2f(x,y) ;
glVertex2f(x,y-1.0F) ;
glEnd() ;
}
void line(int xi,int yi,int xf,int yf,float *c) {
int dx,dy,i,xinc,yinc,cumul,x,y ;
x = xi ;
y = yi ;
dx = xf - xi ;
dy = yf - yi ;
xinc = ( dx > 0 ) ? 1 : -1 ;
yinc = ( dy > 0 ) ? 1 : -1 ;
dx = abs(dx) ;
dy = abs(dy) ;
pixel(x,y,c) ;
if ( dx > dy ) {
cumul = dx / 2 ;
for ( i = 1 ; i <= dx ; i++ ) {
x += xinc ;
cumul += dy ;
if (cumul >= dx) {
cumul -= dx ;
y += yinc ; }
pixel(x,y,c) ; } }
else {
cumul = dy / 2 ;
for ( i = 1 ; i <= dy ; i++ ) {
y += yinc ;
cumul += dx ;
if ( cumul >= dy ) {
cumul -= dy ;
x += xinc ; }
pixel(x,y,c) ; } }
}
void dessineQuadrillage(void) {
float i;
glColor4fv(couleurGrisMoyen()) ;
glBegin(GL_LINES);
for ( i = 0 ; i <= 30 ; i++ ) {
glVertex3d(i,0,-10.0);
glVertex3d(i,20,-10.0); }
for ( i = 0 ; i <= 20 ; i++ ) {
glVertex3d(0,i,-10.0);
glVertex3d(30,i,-10.0); }
glEnd() ;
}
void dessinSegment(segment *s) {
pixel(s->pi.x,s->pi.y,couleurRouge());
pixel(s->pf.x,s->pf.y,couleurVert());
line(s->pi.x,s->pi.y,s->pf.x,s->pf.y,couleurBleu(0.3));
}
void display1() {
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glPushMatrix();
dessineQuadrillage();
switch (aff) {
case 0 :
case 1 :
case 2 :
case 3 :
case 4 :
case 5 :
case 6 :
case 7 : dessinSegment(&s[aff]);
break ; }
glPopMatrix();
glFlush();
glutSwapBuffers() ;
}
void affichePosition(segment *s) {
float pos = 1.0F;
glColor4fv(couleurNoir());
placeFontCursor(5.0F,-pos*20.0F,0.0F) ;
simpleBitmapOutput(1,REGULAR8x13,"PI :%3d %3d",s->pi.x,s->pi.y) ;
pos += 1.0F;
placeFontCursor(5.0F,-pos*20.0F,0.0F) ;
simpleBitmapOutput(1,REGULAR8x13,"PF :%3d %3d",s->pf.x,s->pf.y) ;
}
void display2() {
glClearColor(0.5F,0.5F,0.5F,1.0F);
glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
glPushMatrix();
switch ( aff) {
case 0 :
case 1 :
case 2 :
case 3 :
case 4 :
case 5 :
case 6 :
case 7 : affichePosition(&s[aff]);
break ; }
glPopMatrix();
glutSwapBuffers();
}
void special(int key,int x,int y) {
switch ( key ) {
case GLUT_KEY_RIGHT : if ( pt )
s[aff].pi.x++;
else
s[aff].pf.x++;
glutPostWindowRedisplay(f1);
glutPostWindowRedisplay(f2);
break;
case GLUT_KEY_LEFT : if ( pt )
s[aff].pi.x--;
else
s[aff].pf.x--;
glutPostWindowRedisplay(f1);
glutPostWindowRedisplay(f2);
break;
case GLUT_KEY_UP : if ( pt )
s[aff].pi.y++;
else
s[aff].pf.y++;
glutPostWindowRedisplay(f1);
glutPostWindowRedisplay(f2);
break;
case GLUT_KEY_DOWN : if ( pt )
s[aff].pi.y--;
else
s[aff].pf.y--;
glutPostWindowRedisplay(f1);
glutPostWindowRedisplay(f2);
break; }
}
void key(unsigned char key,int x,int y) {
switch ( key ) {
case 0x20 : pt = !pt;
break;
case 0x0D : aff = (aff+1)%8 ;
glutPostWindowRedisplay(f1);
glutPostWindowRedisplay(f2);
break;
case 0x1B : exit(0);
break; }
}
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();
}
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);
}
int main(int argc,char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
glutInitWindowSize(250,168);
glutInitWindowPosition(50,50);
f1 = glutCreateWindow("Bresenham");
myinit();
creationMenuBasique();
setParametresOrthoBasique(-0.5,20.5,-0.5,20.5,-50.0,50.0);
glutReshapeFunc(reshapeOrthoBasique);
glutKeyboardFunc(key);
glutSpecialFunc(special);
glutDisplayFunc(display1);
glutInitWindowSize(120,50);
glutInitWindowPosition(60,340);
glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
f2 = glutCreateWindow("Valeurs");
creationMenuBasique();
glutDisplayFunc(display2);
glutReshapeFunc(reshape2);
glutKeyboardFunc(key);
glutSpecialFunc(special);
glutMainLoop();
return(0);
}
RETOUR