include pGUI.e
include opengl.e

function resize_cb(Ihandle /*ih*/, integer width, integer height)
    glViewport(0, 0, width, height)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    glOrtho(-30.0, 30.0, -30.0, 30.0, -30.0, 30.0)
    glMatrixMode(GL_MODELVIEW)
    return IUP_DEFAULT
end function

function action(Ihandle /*ih*/)

    glClearColor(0.3,0.3,0.3,0.0)
    glClear(GL_COLOR_BUFFER_BIT+GL_DEPTH_BUFFER_BIT)

    glShadeModel(GL_SMOOTH)

    glLoadIdentity()
    glTranslate(-15.0, -15.0, 0.0)

    glBegin(GL_TRIANGLES)
    glColor(1.0, 0.0, 0.0)
    glVertex(0.0, 0.0)
    glColor(0.0, 1.0, 0.0)
    glVertex(30.0, 0.0)
    glColor(0.0, 0.0, 1.0)
    glVertex(0.0, 30.0)
    glEnd()

    glFlush()

    return IUP_DEFAULT
end function

Ihandle dialog, canvas

function map_cb(Ihandle /*ih*/)
    IupGLMakeCurrent(canvas)
    integer {width, height} = IupGetIntInt(dialog, "RASTERSIZE")
    {} = resize_cb(dialog, width, height)
    return IUP_DEFAULT
end function

IupOpen()
IupGLCanvasOpen()

canvas = IupGLCanvas(Icallback("action"), "RASTERSIZE=640x480")
IupSetCallback(canvas, "RESIZE_CB", Icallback("resize_cb"))

dialog = IupDialog(canvas, "MAP_CB", Icallback("map_cb"), "TITLE=Triangle, SHRINK=YES")

IupShow(dialog)
IupMainLoop()
IupDestroy(dialog)
IupClose()