render
    | gl t k |
    self checkSession.

    gl := display gl.
    display clear: Color white.

    gl color3f_red: 0 green:  0 blue: 0.
    gl pushMatrix.
    self testDraw.
    gl popMatrix.


    t := Time millisecondClockValue.
    frameStats add: t.

    [ t - frameStats first > 5000 ] whileTrue: [ frameStats removeFirst ].


testDraw

    self
        renderQuad: 50@50 p1: 0@100 p2: 100@100;
        renderQuad: 50@50 p1: 100@50 p2: 100@100.


renderQuad: p0 p1: p1 p2: p2

    display gl
        color3d_red: 0.5 green: 0.5 blue: 0.5;
        begin: GL_TRIANGLES;
            texCoord2i_s: 0 t: 0;
            vertex2f_x: p0 x y: p0 y;
            texCoord2f_s: 0.5 t: 0;
            vertex2f_x: p1 x y: p1 y;
            texCoord2i_s: 1 t: 1;
            vertex2f_x: p2 x y: p2 y;
        end