在Opengl应用框架下圆弧的扫描转换算法。要求画一个完整的圆周,圆心在(300,200),半径为50.
#include
#include
#include
#include
#include
using namespace std;
#define pi 3.1415926
void init(void){
glClearColor(1.0, 1.0, 1.0, 0.0);
glMatrixMode(GL_PROJECTION);
gluOrtho2D(0.0, 600.0, 0.0, 600.0);
}
void ChangeSize(GLsizei w, GLsizei h) {
if (h == 0)
h = 1;
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w <= h)
glOrtho(0.0f, 600.0f, 0.0f, 600.0f * h / w, 1.0, -1.0);
else
glOrtho(0.0f, 600.0f * w / h, 0.0f, 600.0f,1.0, -1.0);
}
void CirclePoint(int x0, int y0, int x, int y) {
glColor3f(0.0, 0.0, 1.0);
glVertex2f(x, y); glVertex2f(y - (y0 - x0), x + (y0 - x0));
glVertex2f(y - (y0 - x0), x0 + y0 - x); glVertex2f(x, 2 * y0 - y);
glVertex2f(2 * x0 - x, 2 * y0 - y); glVertex2f(x0 + y0 - y, x0 + y0 - x);
glVertex2f(x0 + y0 - y, x + (y0 - x0)); glVertex2f(2 * x0 - x, y);
}
//中点画圆算法
void MidPointCircle(int x0, int y0, int r){
glColor3f(0.0, 0.0, 1.0);
glPointSize(2.0f);
glVertex2f(x0, y0); //圆心
int x, y;
int d, b;
x = x0; y = r + y0; d = 5 - 4 * r; b = y0 - x0;
CirclePoint(x0, y0, x, y);
while (x + b <= y){
if (d < 0)
d += 8 * (x - x0) + 12;
else {
d += 8 * x - 8 * y + 8 * b + 16;
y--;
}
x++;
CirclePoint(x0, y0, x, y);
}
}
void display(){
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_POINTS);
MidPointCircle(300, 200, 50);
glEnd();
glFlush();
}
int main(int argc, char** argv){
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
glutInitWindowPosition(100, 100);
glutInitWindowSize(500, 500);
glutCreateWindow("Line Algorithm");
glutDisplayFunc(display);
glutReshapeFunc(ChangeSize);
init();
glutMainLoop();
return 0;
}