draw a spriral

#include <gl\glut.h>
#include <math.h>

void renderer(void){
GLfloat ang, x, y, z = -50;

glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(90,1,0,0);
glColor3f(1.0f,0.0f,0.0f);
glBegin(GL_POINTS);
for(ang = 0; ang < 10 * 3.14; ang += .1) {
    x = 70 *sin(ang);
    y = 70 *cos(ang);
    z += .75;
    glVertex3f(x,y,z);
}
glEnd();
glPopMatrix();
glFlush();

}
void changeSize(GLsizei w, GLsizei h) {
GLfloat sideRange = 200;

glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-sideRange, sideRange, -sideRange, sideRange, sideRange, -sideRange);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

}

void main(void)
{
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
glutCreateWindow(“Spiral”);
glutDisplayFunc(renderer);
glutReshapeFunc(changeSize);
glutIdleFunc(renderer);
glutMainLoop();
}

when i execute the program i have a white screen…any soluccion?

You are using double buffered rendering hence you need to make a call to

glutSwapBuffers();

at the end of the render function.

void renderer(void){
   GLfloat ang, x, y, z = -50;
   glClear(GL_COLOR_BUFFER_BIT);
   glPushMatrix();
      glRotatef(90,1,0,0);
      glColor3f(1.0f,0.0f,0.0f);
      glBegin(GL_POINTS);
         for(ang = 0; ang < 10 * 3.14; ang += .1f) {
            x = 70 *sin(ang);
            y = 70 *cos(ang);
	    z += .75;
	    glVertex3f(x,y,z);
	}
      glEnd();
   glPopMatrix();
   glFlush();
   glutSwapBuffers();
}

See if this helps.