private static GLDisplayList CreateSphere(GLContext ctx)
{
int quad = ctx.gluNewQuadric();
ctx.gluQuadricDrawStyle(quad, GLUQuadricDrawStyle.GLU_FILL);
ctx.gluQuadricOrientation(quad, GLUQuadricOrientation.Outside);
GLDisplayList dl = new GLDisplayList(ctx);
dl.Begin();
ctx.gluSphere(quad, 1.0f, 40, 40);
dl.End();
ctx.gluDeleteQuadric(quad);
return(dl);
}