opengl wrapper wrapper, maybe

window.nim

import opengl
when defined(Linux):
  import x, xlib, xutil


type
  PWindow = ref TWindow
  TWindow = object
    when defined(Linux):
      context: GLXcontext
  #  elif defined(Windows):
  #    context: 
proc DrawAQuad()
  
proc newWindow*(width, height: int32): PWindow =
  ##when defined(Linux):
  var
    dpy: PDisplay
    root: x.TWindow
    attributes = [GLX_RGBA, GLX_DEPTH_SIZE, 24, GLX_DOUBLEBUFFER, GLX_NONE]
    vinfo: PXVisualInfo
    swa: TXsetWindowAttributes
    window: x.TWindow
    cmap: TColorMap
    glc: GLXcontext
  dpy = XOpenDisplay(nil)
  if dpy.isNil:
    echo "Cannot connect to X server."
    return
  root = XDefaultRootWindow(dpy)
  
  loadExtensions()
  
  vinfo = glxChooseVisual(dpy, 0, addr attributes[0])
  cmap = XCreateColormap(dpy, root, vinfo.visual, AllocNone)
  swa.colormap = cmap
  swa.event_mask = ExposureMask or KeyPressMask
  window = XCreateWindow(dpy, root, 0, 0, width.cuint, height.cuint, 0,
    vinfo.depth, x.CopyFromParent, vinfo.visual, CWColormap or CWeventMask,
    addr swa)
    
  echo XMapWindow(dpy, window)
  echo XStoreName(dpy, window, "Sup dude.")
  
  glc = glxcreateContext(dpy, vinfo, nil, true)
  echo glxmakeCurrent(dpy, window, glc)
  glEnable GL_DEPTH_TEST
  
  var 
    xev: TXevent
    xwa: TXWindowAttributes
  while true:
    echo xnextevent(dpy, addr xev)
    if xev.theType == Expose:
      discard xgetWindowAttributes(dpy, window, addr xwa)
      glViewport(0, 0, xwa.width, xwa.height)
      drawAQuad()
      glxSwapBuffers(dpy, window)
    elif xev.theType == keyPress:
      discard glxmakeCurrent(dpy, GL_NONE, nil)
      glxDestroyContext(dpy, glc)
      discard XDestroyWindow(dpy, window)
      discard XCloseDisplay(dpy)
      break

proc DrawAQuad() =
  glClearColor(1.0, 1.0, 1.0, 1.0)
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT)

  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
  glOrtho(-1.0, 1.0, -1.0, 1.0, 1.0, 20.0)

  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
  gluLookAt(0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0)

  glBegin(GL_QUADS)
  glColor3f(1.0, 0.0, 0.0) 
  glVertex3f(-0.75, -0.75, 0.0)
  glColor3f(0.0, 1.0, 0.0) 
  glVertex3f(0.75, -0.75, 0.0)
  glColor3f(0.0, 0.0, 1.0) 
  glVertex3f(0.75, 0.75, 0.0)
  glColor3f(1.0, 1.0, 0.0) 
  glVertex3f(-0.75, 0.75, 0.0)
  glEnd()

when isMainModule:
  var w = newWindow(500, 250)