c++ - 在 OpenGL 中用一些颜色填充 Bresenham 圆

Question

我正在使用这个 Bresenham 算法来画圆。此代码有效，但我需要实心圆，而不仅仅是边框。

这是我的代码:

void setPixel(int x,int y)  {  
    glBegin(GL_POINTS); 
    glColor3f(0.0f, 1.0f, 0.0f);
    glPointSize (20.0);
    glVertex2i(x,y);
    glEnd();
}

void BresenhamKrug(int xCenter, int yCenter,int r){ //napravite parametarski poziv
int x=0,y=r;
int d=3-(2*r);

glColor3f(0.5,0.3,1.); 


while(x<=y)
{
    setPixel(xCenter+x,yCenter+y);  setPixel(xCenter+y,yCenter+x);
    setPixel(xCenter-x,yCenter+y);  setPixel(xCenter+y,yCenter-x); 
    setPixel(xCenter-x,yCenter-y);  setPixel(xCenter-y,yCenter-x); 
    setPixel(xCenter+x,yCenter-y);  setPixel(xCenter-y,yCenter+x); 

    if (d<0)
        d += (4*x)+6;
    else{
          d += (4*(x-y))+10;
          y--;
    }

    x++;
}
glFlush();
}

有什么办法吗？

Answer 1

您可以将点保存在数组中并绘制多边形，或者 triangle fans .

glBegin(GL_POLYGON);

或:

void BresenhamKrug(int xCenter, int yCenter,int r){ //napravite parametarski poziv
    int x=0,y=r;
    int d=3-(2*r);

    glColor3f(0.5,0.3,1.); 

    glBegin(GL_POLYGON);

    while(x<=y)
    {
        glVertex2i(xCenter+x,yCenter+y);  glVertex2i(xCenter+y,yCenter+x);
        glVertex2i(xCenter-x,yCenter+y);  glVertex2i(xCenter+y,yCenter-x); 
        glVertex2i(xCenter-x,yCenter-y);  glVertex2i(xCenter-y,yCenter-x); 
        glVertex2i(xCenter+x,yCenter-y);  glVertex2i(xCenter-y,yCenter+x); 

        if (d<0)
            d += (4*x)+6;
        else{
              d += (4*(x-y))+10;
              y--;
        }

        x++;
    }
    glEnd();
    glFlush();
}

但不确定一个简单的圆方程是否足够.. drawing circle , 光栅化为 handled通过 openGL。