gl.glPushMatrix();
gl.glMaterialfv(GL.GL_FRONT, GL.GL_EMISSION, green,0);
gl.glColor3f(0, 1, 0);
gl.glTranslatef(0, ylen, 0);
gl.glScalef(ylen/WIDTH, ylen/WIDTH, 1);
glut.glutStrokeCharacter(GLUT.STROKE_ROMAN, 'Y');
gl.glPopMatrix();
gl.glPushMatrix();
gl.glMaterialfv(GL.GL_FRONT, GL.GL_EMISSION, red,0);
gl.glColor3f(1, 0, 0);