diamond.c

图形学课件 图形学课件 图形学课件

/* gasket.c   */

/* E. Angel, Interactive Computer Graphics */
/* A Top-Down Approach with OpenGL, Third Edition */
/* Addison-Wesley Longman, 2003 */

/* Two-Dimensional Sierpinski Gasket          */
/* Generated Using Randomly Selected Vertices */
/* And Bisection                              */

#include <GL/glut.h>
#include "math.h"

#define PI 3.14159
#define NUMBER  8
#define RADIUS	400

//===================================================================
void myinit(void)
{
 
/* attributes */

      glClearColor(1.0, 1.0, 1.0, 1.0); /* white background */
      glColor3f(0.0, 0.0, 1.0); /* draw in red */

/* set up viewing */
/* 500 x 500 window with origin lower left */

      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      gluOrtho2D(-500.0, 500.0, -500.0, 500.0);
      glMatrixMode(GL_MODELVIEW);

	  glEnable(GL_COLOR_LOGIC_OP);
}


//===================================================================
void display( void )
{
	/* define a point data type */

    typedef GLfloat point2[2];     

    point2 vertices[NUMBER];

    int i,j;
   
    glClear(GL_COLOR_BUFFER_BIT);  /*clear the window */

	for(i=0;i<NUMBER;i++)
	{
		vertices[i][0] = RADIUS*cos(PI/NUMBER+2*PI*i/NUMBER);
		vertices[i][1] = RADIUS*sin(PI/NUMBER+2*PI*i/NUMBER);
	}

	for(i=0;i<NUMBER;i++)
		for(j=i+1;j<NUMBER;j++)
		{
          glBegin(GL_LINES);
              glVertex2fv(vertices[i]); 
			  glVertex2fv(vertices[j]);
          glEnd();
		}

    
     glFlush(); /* clear buffers */
}


//===================================================================
void main(int argc, char** argv)
{

/* Standard GLUT initialization */

    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); /* default, not needed */
    glutInitWindowSize(500,500); /* 500 x 500 pixel window */
    glutInitWindowPosition(0,0); /* place window top left on display */
    glutCreateWindow("Sierpinski Gasket"); /* window title */
    glutDisplayFunc(display); /* display callback invoked when window opened */
	
	myinit(); /* set attributes */

    glutMainLoop(); /* enter event loop */
}