//*** Animation of a GLUT wireframe cone -- use of idle() callback

// w32ogl Project / Properties:
  // Must add Linker / Input / Additional Dependencies: opengl32.lib glu32.lib glut32.lib
  // Must set Linker / Advanced / Entry Point to: mainCRTStartup 

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

GLint winWidth=500, winHeight=500;
GLfloat theta = 0.0;
int doubleb;

void init(void)
{
        glClearColor(1.0,1.0,1.0,0.0);
        glColor3f(1.0,1.0,1.0); 
        glMatrixMode(GL_PROJECTION); 
        glLoadIdentity();
        glFrustum(-1.0,1.0,-1.0,1.0,1.0,10.0);
    
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(2.0,2.0,2.0,0.0,0.0,0.0,0.0,0.0,1.0);
}

void displayd(void)
{
        glClear(GL_COLOR_BUFFER_BIT);
        glColor3f(0.0,0.0,1.0);

        //*** display the coordinate axes
        glBegin(GL_LINES);
                glVertex3f(0.0,0.0,0.0);
                glVertex3f(0.0,0.0,2.0);
                glVertex3f(0.0,0.0,0.0);
                glVertex3f(0.0,2.0,0.0);
                glVertex3f(0.0,0.0,0.0);
                glVertex3f(2.0,0.0,0.0);
        glEnd();

        glPushMatrix();  // fix coordinate axes
        glRotatef(theta,0.0,1.0,0.0);  // about y axis -- ok
        //glRotatef(theta,0.0,0.0,1.0);  // about z axis -- ok
        glColor3f(1.0,0.0,0.0);
        glutWireCone(1.5,1.5,12,6);
        glPopMatrix();

        //delay a bit
        for (int i=0; i<=9999999; i++);
        glutSwapBuffers();
}

void spinDisplay(void)
{
        theta += 1.0;
        if (theta >= 360.0) theta -= 360.0;
        glutPostRedisplay();
}

void myReshape(int w, int h)
{
        glViewport(0,0,w,h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glFrustum(-1.0,1.0,-1.0,1.0,1.0,10.0);

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(2.0,2.0,2.0,0.0,0.0,0.0,0.0,0.0,1.0);
}

void main(int argc, char** argv)
{
        glutInit(&argc,argv);
        glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
        doubleb=glutCreateWindow("Animation of a Wireframe Cone");
        init();
        glutDisplayFunc(displayd);
        glutReshapeFunc(myReshape);
        glutIdleFunc(spinDisplay);
        glutMainLoop();
}