[실습 02] 랜덤 바둑판 모양 그리기

#include <gl/glut.h>
#include <time.h>
#include <stdlib.h>

​

GLvoid drawScene(GLvoid);
GLvoid Reshape(int w, int h);

​

void main()
{
 srand((unsigned)time(NULL));
 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
 glutInitWindowPosition(100, 100);
 glutInitWindowSize(800, 800);
 glutCreateWindow("Example2");
 glutDisplayFunc(drawScene);
 glutReshapeFunc(Reshape);
 glutMainLoop();
}

​

GLvoid drawScene(GLvoid)
{
 int num = rand() % 6 + 3;
 int width;
 width = 800 / num;
 glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
 glClear(GL_COLOR_BUFFER_BIT);

 for (int i = 0; i < num; ++i)
 {
  for (int j = 0; j < num; ++j)
  {
   if (i % 2)
   {
    if (j % 2)
    {
     glColor4f(1.0f, 0.0f, 0.0f, 0.0f);
     glRectf(width * j, width * i, width * j + width, width * i + width);
    }
    else
    {
     glColor4f(0.0f, 1.0f, 0.0f, 0.0f);
     glRectf(width * j, width * i, width * j + width, width * i + width);
    }
   }
   else
   {
    if (j % 2)
    {
     glColor4f(0.0f, 1.0f, 0.0f, 0.0f);
     glRectf(width * j, width * i, width * j + width, width * i + width);
    }
    else
    {
     glColor4f(1.0f, 0.0f, 0.0f, 0.0f);
     glRectf(width * j, width * i, width * j + width, width * i + width);
    }
   }
  }
 }

 glFlush();
}


GLvoid Reshape(int w, int h)
{
 glViewport(0, 0, w, h);
 glOrtho(0.0, 800.0, 0.0, 800.0, -1.0, 1.0);
}