static void reshape(int width, int height)
{
double aspectRatio = (float)width / (float)height;
double fieldOfView = 40.0; /* Degrees */
/* Build projection matrix once. */
buildPerspectiveMatrix(fieldOfView, aspectRatio,
1.0, 20.0, /* Znear and Zfar */
ref myProjectionMatrix);
Gl.glViewport(0, 0, width, height);
}