扫描线填充算法--有效边表填充算法

代码：

draw.cpp //using OpenGL

#include "opengl.h"

#include

#include

#include

#include

#define PN 6

int

point [N ][2]={{40, 5},{75, 40},{60, 70},{35, 50},{25, 80},{5, 30}};

//AE

struct AE{

AE(float _x, float _dx, int

_ymax){x =_x; dx =_dx; ymax =_ymax;}

float x;

float dx;

int ymax;

void operator ++(int ){

x+=dx ;

}

};

//AET

//which eage is on the right

bool fill_comp(const AE& ae1, const AE& ae2){ if (ae1. x

return true ;

}

if (ae1. x ==ae2. x &&ae1. dx

return true ;

}

return false ;

}

void fillline(int y, int x1, int x2){

for (int i=x1; i

flush();

}

void fill(){

//make k=(x2-x1)/(y2-y1)

float k[PN ]={0.0};for (int

i =0; i !=PN ; i ++){k [i ]=((float )(point [(i +1)%PN ][0]-point [i ][0])/(float )(point [(i +1)%PN ][1]-point [i ][1]));}

//find min and max with selection sort.

int min=point [0][1],max =min ; for (int

i =0; i !=PN ; i ++){if (point [i ][1]>max ){max =point [i ][1];};;if (point [i ][1]

//make scanning line list

std::vector *ET = new std::vector [max -min +1]; //make ET

//

for (int i = 0; i

//get ymin, ymax

int yminn=point [i ][1]

int ymaxn=point [i ][1]>=point [(i +1)%PN ][1] ? i : (i +1)%PN ;

AE *tmp = new

AE (point [yminn ][0],k [i ],point [ymaxn ][1]);

//insert node

ET[point [yminn ][1]-min ].push_back(*tmp );

}

//init AET

std::vector AET;

for (int i=0; i !=max -min +1; i ++){

//insert node from ET to AET

for (int ii=0; ii !=ET [i ].size ();ii ++){

//sort with selection sort.

AET. insert (std ::upper_bound(AET . begin (), AET . end (),ET [i ][ii ],fill_comp), ET [i ][ii ]);

}

//delete y=ymax,"下闭上开"

for (int

ii =0; ii !=AET . size ();){if (i +min ==AET [ii ].ymax )

{AET . erase (AET . begin ()+ii );}else {ii ++;}}

//draw

{

bool flag=false ;

for (int ii=0; ii !=AET . size ();ii ++){

if (flag )

fillline (i +min ,(int )(AET [ii -1].x +0.5),(int )(AET [ii ].x +0.5));

//if(flag)

std::cout

flag=!flag ;

} }

for (int ii=0; ii !=AET . size ();ii ++){AET [ii ]++;} }

delete [](ET );

}

void draw(){

drawgrid(0.8, 0.8, 0.8);

setcolor(1, 0.5, 0.5);

fill();

draweage(point , PN );

}

int main(int n, char *avg []){

init(n , avg , "L2" );

reinit(draw );

loop();

return 0;

}

opengl.h

#include

#define N 100

#define GRIDSIZE 5

int size=N *GRIDSIZE ;

void init(int argc, char ** argv, char *title ){

//init openGL

size = N * GRIDSIZE;

glutInit(&argc , argv);

glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);

glutInitWindowPosition(10, 10);

glutInitWindowSize(size , size);

glutCreateWindow(title );

glClearColor(1.0, 1.0, 1.0, 1.0); //white

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(0.0, 0.0, 0.0); //black

gluOrtho2D(0, size, 0, size);

}

void reinit(void (*p )()){

glutDisplayFunc(p );

}

void flush(){

glFlush();

}

void loop(){

glutMainLoop();

}

void clear(){

glClearColor(1.0, 1.0, 1.0, 1.0); //white

glClear(GL_COLOR_BUFFER_BIT);

}

void setcolor(double r, double g, double b){

glColor3f(r , g, b);

}

void drawline(int x1, int y1, int x2, int y2){

glBegin(GL_LINES);

glVertex2i(x1, y1);

glVertex2i(x2, y2);

glEnd();

flush();

}

void drawgrid(double r, double g, double b){

int i = 0;

glColor3f(r , g, b);

for (i = 0; i != N * GRIDSIZE ; i += GRIDSIZE ) { drawline (i , 0, i, size); }

for (i = 0; i != N * GRIDSIZE ; i += GRIDSIZE ) { drawline (0, i , size, i); }

flush();

}

void drawpoint(int x, int y){

glPointSize((double ) GRIDSIZE );

glBegin(GL_POINTS);

glVertex2i(x * GRIDSIZE, y * GRIDSIZE);

glEnd();

flush();

}

void draweage(int p[][2],int pn){

if (pn

setcolor(0, 0.8, 0.8);

for (int i=0; i !=pn -1; i ++){

drawline (p [i ][0]*GRIDSIZE , p [i ][1]*GRIDSIZE , p [i +1][0]*GRID SIZE , p [i +1][1]*GRIDSIZE );

}

drawline (p [pn -1][0]*GRIDSIZE , p [pn -1][1]*GRIDSIZE , p [0][0]*GRIDSIZE , p [0][1]*GRIDSIZE );

}

运行环境： ubuntu 13.10 + g++ 运行结果：

代码：

draw.cpp //using OpenGL

#include "opengl.h"

#include

#include

#include

#include

#define PN 6

int

point [N ][2]={{40, 5},{75, 40},{60, 70},{35, 50},{25, 80},{5, 30}};

//AE

struct AE{

AE(float _x, float _dx, int

_ymax){x =_x; dx =_dx; ymax =_ymax;}

float x;

float dx;

int ymax;

void operator ++(int ){

x+=dx ;

}

};

//AET

//which eage is on the right

bool fill_comp(const AE& ae1, const AE& ae2){ if (ae1. x

return true ;

}

if (ae1. x ==ae2. x &&ae1. dx

return true ;

}

return false ;

}

void fillline(int y, int x1, int x2){

for (int i=x1; i

flush();

}

void fill(){

//make k=(x2-x1)/(y2-y1)

float k[PN ]={0.0};for (int

i =0; i !=PN ; i ++){k [i ]=((float )(point [(i +1)%PN ][0]-point [i ][0])/(float )(point [(i +1)%PN ][1]-point [i ][1]));}

//find min and max with selection sort.

int min=point [0][1],max =min ; for (int

i =0; i !=PN ; i ++){if (point [i ][1]>max ){max =point [i ][1];};;if (point [i ][1]

//make scanning line list

std::vector *ET = new std::vector [max -min +1]; //make ET

//

for (int i = 0; i

//get ymin, ymax

int yminn=point [i ][1]

int ymaxn=point [i ][1]>=point [(i +1)%PN ][1] ? i : (i +1)%PN ;

AE *tmp = new

AE (point [yminn ][0],k [i ],point [ymaxn ][1]);

//insert node

ET[point [yminn ][1]-min ].push_back(*tmp );

}

//init AET

std::vector AET;

for (int i=0; i !=max -min +1; i ++){

//insert node from ET to AET

for (int ii=0; ii !=ET [i ].size ();ii ++){

//sort with selection sort.

AET. insert (std ::upper_bound(AET . begin (), AET . end (),ET [i ][ii ],fill_comp), ET [i ][ii ]);

}

//delete y=ymax,"下闭上开"

for (int

ii =0; ii !=AET . size ();){if (i +min ==AET [ii ].ymax )

{AET . erase (AET . begin ()+ii );}else {ii ++;}}

//draw

{

bool flag=false ;

for (int ii=0; ii !=AET . size ();ii ++){

if (flag )

fillline (i +min ,(int )(AET [ii -1].x +0.5),(int )(AET [ii ].x +0.5));

//if(flag)

std::cout

flag=!flag ;

} }

for (int ii=0; ii !=AET . size ();ii ++){AET [ii ]++;} }

delete [](ET );

}

void draw(){

drawgrid(0.8, 0.8, 0.8);

setcolor(1, 0.5, 0.5);

fill();

draweage(point , PN );

}

int main(int n, char *avg []){

init(n , avg , "L2" );

reinit(draw );

loop();

return 0;

}

opengl.h

#include

#define N 100

#define GRIDSIZE 5

int size=N *GRIDSIZE ;

void init(int argc, char ** argv, char *title ){

//init openGL

size = N * GRIDSIZE;

glutInit(&argc , argv);

glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);

glutInitWindowPosition(10, 10);

glutInitWindowSize(size , size);

glutCreateWindow(title );

glClearColor(1.0, 1.0, 1.0, 1.0); //white

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(0.0, 0.0, 0.0); //black

gluOrtho2D(0, size, 0, size);

}

void reinit(void (*p )()){

glutDisplayFunc(p );

}

void flush(){

glFlush();

}

void loop(){

glutMainLoop();

}

void clear(){

glClearColor(1.0, 1.0, 1.0, 1.0); //white

glClear(GL_COLOR_BUFFER_BIT);

}

void setcolor(double r, double g, double b){

glColor3f(r , g, b);

}

void drawline(int x1, int y1, int x2, int y2){

glBegin(GL_LINES);

glVertex2i(x1, y1);

glVertex2i(x2, y2);

glEnd();

flush();

}

void drawgrid(double r, double g, double b){

int i = 0;

glColor3f(r , g, b);

for (i = 0; i != N * GRIDSIZE ; i += GRIDSIZE ) { drawline (i , 0, i, size); }

for (i = 0; i != N * GRIDSIZE ; i += GRIDSIZE ) { drawline (0, i , size, i); }

flush();

}

void drawpoint(int x, int y){

glPointSize((double ) GRIDSIZE );

glBegin(GL_POINTS);

glVertex2i(x * GRIDSIZE, y * GRIDSIZE);

glEnd();

flush();

}

void draweage(int p[][2],int pn){

if (pn

setcolor(0, 0.8, 0.8);

for (int i=0; i !=pn -1; i ++){

drawline (p [i ][0]*GRIDSIZE , p [i ][1]*GRIDSIZE , p [i +1][0]*GRID SIZE , p [i +1][1]*GRIDSIZE );

}

drawline (p [pn -1][0]*GRIDSIZE , p [pn -1][1]*GRIDSIZE , p [0][0]*GRIDSIZE , p [0][1]*GRIDSIZE );

}

运行环境： ubuntu 13.10 + g++ 运行结果：


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