c++ - 填充矩形并在 opengl 中应用非零缠绕规则

Question

这是 opengl 中的简单矩形绘图代码..我想用一些颜色填充矩形并想应用非零缠绕规则来告诉用户矩形是填充内部还是外部...我怎样才能实现这？？？

#include <cstdlib>
#include <iostream>
#include<GL/glut.h>

using namespace std;

#include <GL/glut.h>

void display(void)
{
   glClear (GL_COLOR_BUFFER_BIT);


   glColor3f (1.0, 1.0, 1.0);
   glBegin(GL_POLYGON);
      glVertex3f (0.25, 0.25, 0.0);
      glVertex3f (0.75, 0.25, 0.0);
      glVertex3f (0.75, 0.75, 0.0);
      glVertex3f (0.25, 0.75, 0.0);
   glEnd();


   glFlush ();
}

void init (void) 
{

   glClearColor (0.0, 0.0, 0.0, 0.0);


   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}


int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize (250, 250); 
   glutInitWindowPosition (100, 100);
   glutCreateWindow ("hello");
   init ();
   glutDisplayFunc(display); 
   glutMainLoop();
   return 0;  
}

Answer 1

使用 GLU Tesselator .