/* Auteur: Nicolas JANEY */
/* nicolas.janey@univ-fcomte.fr */
/* Avril 2002 */
/* Clipping 2D */
#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 "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 segment s1 = { 2,10,27,19 } ;
static segment s2 = { 5,9,28,4 } ;
static int disc = 1 ;
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 pixelClip(rectangle *r,int x,int y,float *c) {
if ( ( x >= r->sg.x ) && ( y >= r->sg.y ) && ( x <= r->id.x ) && ( y <= r->id.y ) )
pixel(x,y,c) ;
}
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 traceRectangle(rectangle *r,float *c) {
line(r->id.x,r->id.y-1,r->id.x,r->sg.y+1,c) ;
line(r->id.x,r->sg.y,r->sg.x,r->sg.y,c) ;
line(r->id.x,r->id.y,r->sg.x,r->id.y,c) ;
line(r->sg.x,r->id.y-1,r->sg.x,r->sg.y+1,c) ;
}
void clipperSegment(rectangle *r,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) ;
pixelClip(r,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 ; }
pixelClip(r,x,y,c) ; } }
else {
cumul = dy / 2 ;
for ( i = 1 ; i <= dy ; i++ ) {
y += yinc ;
cumul += dx ;
if ( cumul >= dy ) {
cumul -= dy ;
x += xinc ; }
pixelClip(r,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 display() {
rectangle r = { 6,5,26,15 } ;
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glPushMatrix();
dessineQuadrillage();
traceRectangle(&r,couleurRouge(0.6F));
switch ( aff) {
case 1 : line(s1.pi.x,s1.pi.y,s1.pf.x,s1.pf.y,couleurBleu(0.5));
line(s2.pi.x,s2.pi.y,s2.pf.x,s2.pf.y,couleurVertFonce(0.5));
break ;
case 2 : line(s1.pi.x,s1.pi.y,s1.pf.x,s1.pf.y,couleurBleu(0.3));
line(s2.pi.x,s2.pi.y,s2.pf.x,s2.pf.y,couleurVertFonce(0.3));
clipperSegment(&r,s1.pi.x,s1.pi.y,s1.pf.x,s1.pf.y,couleurBleu(0.8));
clipperSegment(&r,s2.pi.x,s2.pi.y,s2.pf.x,s2.pf.y,couleurVertFonce(0.8));
break ; }
glPopMatrix();
glFlush();
glutSwapBuffers() ;
}
void key(unsigned char key,int x,int y) {
switch ( key ) {
case 0x0D : aff = (aff+1)%3 ;
glutPostRedisplay();
break;
case 0x1B : exit(0);
break; }
}
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(375,252);
glutInitWindowPosition(50,50);
glutCreateWindow("Clipping 2D");
myinit();
creationMenuBasique();
setParametresOrthoBasique(-0.5,20.5,-0.5,20.5,-50.0,50.0);
glutReshapeFunc(reshapeOrthoBasique);
glutKeyboardFunc(key);
glutDisplayFunc(display);
glutMainLoop();
return(0);
}
RETOUR