#!/usr/bin/env ruby

require 'fox16'
begin
  require 'opengl'
rescue LoadError
  require 'fox16/missingdep'
  MSG = <<EOM
  Sorry, this example depends on the opengl-bindings gems. Please execute:
    gem install opengl-bindings
EOM
  missingDependency(MSG)
end



class GLTestWindow < Fox::FXMainWindow
  include Fox
  include OpenGL

  # How often our timer will fire (in milliseconds)
  TIMER_INTERVAL = 100

  # Draws a simple box using the given corners
  def drawBox(xmin, ymin, zmin, xmax, ymax, zmax)
    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(0.0, 0.0, -1.0)
      glVertex3d(xmin, ymin, zmin)
      glVertex3d(xmin, ymax, zmin)
      glVertex3d(xmax, ymin, zmin)
      glVertex3d(xmax, ymax, zmin)
    glEnd()

    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(1.0, 0.0, 0.0)
      glVertex3d(xmax, ymin, zmin)
      glVertex3d(xmax, ymax, zmin)
      glVertex3d(xmax, ymin, zmax)
      glVertex3d(xmax, ymax, zmax)
    glEnd()

    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(0.0, 0.0, 1.0)
      glVertex3d(xmax, ymin, zmax)
      glVertex3d(xmax, ymax, zmax)
      glVertex3d(xmin, ymin, zmax)
      glVertex3d(xmin, ymax, zmax)
    glEnd()

    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(-1.0, 0.0, 0.0)
      glVertex3d(xmin, ymin, zmax)
      glVertex3d(xmin, ymax, zmax)
      glVertex3d(xmin, ymin, zmin)
      glVertex3d(xmin, ymax, zmin)
    glEnd()

    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(0.0, 1.0, 0.0)
      glVertex3d(xmin, ymax, zmin)
      glVertex3d(xmin, ymax, zmax)
      glVertex3d(xmax, ymax, zmin)
      glVertex3d(xmax, ymax, zmax)
    glEnd()

    glBegin(GL_TRIANGLE_STRIP)
      glNormal3d(0.0, -1.0, 0.0)
      glVertex3d(xmax, ymin, zmax)
      glVertex3d(xmax, ymin, zmin)
      glVertex3d(xmin, ymin, zmax)
      glVertex3d(xmin, ymin, zmin)
    glEnd()
  end

  def gluPerspective(fovY, aspect, zNear, zFar )
    fH = Math.tan( fovY / 360 * Math::PI ) * zNear;
    fW = fH * aspect;

    glFrustum( -fW, fW, -fH, fH, zNear, zFar );
  end

  # Define our own version of gluLookAt() to avoid dependency to deprecated GLU library
  def gluLookAt(ex, ey, ez,
           lx, ly, lz,
           ux, uy, uz )
    z0 = ex - lx
    z1 = ey - ly
    z2 = ez - lz
    l = z0*z0+z1*z1+z2*z2
    if l != 0 then
      l = 1.0 / Math.sqrt(l)
      z0 *= l
      z1 *= l
      z2 *= l
    end

    x0 = uy*z2-uz*z1
    x1 = -ux*z2+uz*z0
    x2 = ux*z1-uy*z0
    l = x0*x0+x1*x1+x2*x2
    if l != 0 then
      l = 1.0 / Math.sqrt(l)
      x0 *= l
      x1 *= l
      x2 *= l
    end

    y0 = z1*x2-z2*x1
    y1 = -z0*x2+z2*x0
    y2 = z0*x1-z1*x0
    l = y0*y0+y1*y1+y2*y2
    if l != 0 then
      l = 1.0 / Math.sqrt(l)
      y0 *= l
      y1 *= l
      y2 *= l
    end

    m4x4 = [
      x0,y0,z0,0,
      x1,y1,z1,0,
      x2,y2,z2,0,
      0,  0, 0,1,
    ].pack("d*")
    glMultMatrixd m4x4
    glTranslated -ex,-ey,-ez
  end

  # Draw the GL scene
  def drawScene
    lightPosition = [15.0, 10.0, 5.0, 1.0]
    lightAmbient  = [ 0.1,  0.1, 0.1, 1.0]
    lightDiffuse  = [ 0.9,  0.9, 0.9, 1.0]
    redMaterial   = [ 1.0,  0.0, 0.0, 1.0]
    blueMaterial  = [ 0.0,  0.0, 1.0, 1.0]

    width = @glcanvas.width.to_f
    height = @glcanvas.height.to_f
    aspect = width/height

    # Make context current
    @glcanvas.makeCurrent()

    glViewport(0, 0, @glcanvas.width, @glcanvas.height)

    glClearColor(1.0, 1.0, 1.0, 1.0)
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
    glEnable(GL_DEPTH_TEST)

    glDisable(GL_DITHER)

    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluPerspective(30.0, aspect, 1.0, 100.0)

    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()
    gluLookAt(5.0, 10.0, 15.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0)

    glShadeModel(GL_SMOOTH)
    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition.pack("f*"))
    glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient.pack("f*"))
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse.pack("f*"))
    glEnable(GL_LIGHT0)
    glEnable(GL_LIGHTING)

    glMaterialfv(GL_FRONT, GL_AMBIENT, blueMaterial.pack("f*"))
    glMaterialfv(GL_FRONT, GL_DIFFUSE, blueMaterial.pack("f*"))

    glPushMatrix()
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-1, -1, -1, 1, 1, 1)

    glMaterialfv(GL_FRONT, GL_AMBIENT, redMaterial.pack("f*"))
    glMaterialfv(GL_FRONT, GL_DIFFUSE, redMaterial.pack("f*"))

    glPushMatrix()
    glTranslated(0.0, 1.75, 0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5, -0.5, -0.5, 0.5, 0.5, 0.5)
    glPopMatrix()

    glPushMatrix()
    glTranslated(0.0, -1.75, 0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5, -0.5, -0.5, 0.5, 0.5, 0.5)
    glPopMatrix()

    glPushMatrix()
    glRotated(90.0, 1.0, 0.0, 0.0)
    glTranslated(0.0, 1.75, 0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5,-0.5,-0.5,0.5,0.5,0.5)
    glPopMatrix()

    glPushMatrix()
    glRotated(90.0, -1.0, 0.0, 0.0)
    glTranslated(0.0,1.75,0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5,-0.5,-0.5,0.5,0.5,0.5)
    glPopMatrix()

    glPushMatrix()
    glRotated(90.0, 0.0, 0.0, 1.0)
    glTranslated(0.0,1.75,0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5,-0.5,-0.5,0.5,0.5,0.5)
    glPopMatrix()

    glPushMatrix()
    glRotated(90.0, 0.0, 0.0, -1.0)
    glTranslated(0.0,1.75,0.0)
    glRotated(@angle, 0.0, 1.0, 0.0)
    drawBox(-0.5,-0.5,-0.5,0.5,0.5,0.5)
    glPopMatrix()

    glPopMatrix()

    # Swap if it is double-buffered
    if @glvisual.isDoubleBuffer
      @glcanvas.swapBuffers
    end

    # Make context non-current
    @glcanvas.makeNonCurrent
  end

  def initialize(app)
    # Invoke the base class initializer
    super(app, "OpenGL Test Application", :opts => DECOR_ALL, :width => 800, :height => 600)

    OpenGL.load_lib

    # Construct the main window elements
    frame = FXHorizontalFrame.new(self, LAYOUT_SIDE_TOP|LAYOUT_FILL_X|LAYOUT_FILL_Y)
    frame.padLeft, frame.padRight = 0, 0
    frame.padTop, frame.padBottom = 0, 0

    # Left pane to contain the glcanvas
    glcanvasFrame = FXVerticalFrame.new(frame,
      LAYOUT_FILL_X|LAYOUT_FILL_Y|LAYOUT_TOP|LAYOUT_LEFT)
    glcanvasFrame.padLeft, glcanvasFrame.padRight = 10, 10
    glcanvasFrame.padTop, glcanvasFrame.padBottom = 10, 10

    # Label above the glcanvas
    FXLabel.new(glcanvasFrame, "OpenGL Canvas Frame", nil,
      JUSTIFY_CENTER_X|LAYOUT_FILL_X)

    # Horizontal divider line
    FXHorizontalSeparator.new(glcanvasFrame, SEPARATOR_GROOVE|LAYOUT_FILL_X)

    # Drawing glcanvas
    glpanel = FXVerticalFrame.new(glcanvasFrame, (FRAME_SUNKEN|FRAME_THICK|
      LAYOUT_FILL_X|LAYOUT_FILL_Y|LAYOUT_TOP|LAYOUT_LEFT))
    glpanel.padLeft, glpanel.padRight = 0, 0
    glpanel.padTop, glpanel.padBottom = 0, 0

    # A visual to draw OpenGL
    @glvisual = FXGLVisual.new(getApp(), VISUAL_DOUBLEBUFFER)

    # Drawing glcanvas
    @glcanvas = FXGLCanvas.new(glpanel, @glvisual, :opts => LAYOUT_FILL_X|LAYOUT_FILL_Y|LAYOUT_TOP|LAYOUT_LEFT)
    @glcanvas.connect(SEL_PAINT) { drawScene }
    @glcanvas.connect(SEL_CONFIGURE) do
      if @glcanvas.makeCurrent
        glViewport(0, 0, @glcanvas.width, @glcanvas.height)
        @glcanvas.makeNonCurrent
      end
    end

    # Right pane for the buttons
    buttonFrame = FXVerticalFrame.new(frame, LAYOUT_FILL_Y|LAYOUT_TOP|LAYOUT_LEFT)
    buttonFrame.padLeft, buttonFrame.padRight = 10, 10
    buttonFrame.padTop, buttonFrame.padBottom = 10, 10

    # Label above the buttons
    FXLabel.new(buttonFrame, "Button Frame", nil,
      JUSTIFY_CENTER_X|LAYOUT_FILL_X)

    # Horizontal divider line
    FXHorizontalSeparator.new(buttonFrame, SEPARATOR_RIDGE|LAYOUT_FILL_X)

    # Spin according to timer
    spinTimerBtn = FXButton.new(buttonFrame, "Spin &Timer\tSpin using interval timers\nNote the app blocks until the interal has elapsed...",nil,nil,0,FRAME_THICK|FRAME_RAISED|LAYOUT_FILL_X|LAYOUT_TOP|LAYOUT_LEFT)
    spinTimerBtn.padLeft, spinTimerBtn.padRight = 10, 10
    spinTimerBtn.padTop, spinTimerBtn.padBottom = 5, 5
    spinTimerBtn.connect(SEL_COMMAND) do
      @spinning = true
      @timer = getApp().addTimeout(TIMER_INTERVAL, :repeat => true) do
        @angle += 2.0
        if @angle > 360.0
          @angle -= 360.0
        end
        drawScene()
      end
    end
    spinTimerBtn.connect(SEL_UPDATE) do |sender, sel, ptr|
      @spinning ? sender.disable : sender.enable
    end

    # Spin according to chore
    spinChoreBtn = FXButton.new(buttonFrame,
      "Spin &Chore\tSpin as fast as possible using chores\nNote even though the
      app is very responsive, it never blocks;\nthere is always something to
      do...", :opts => FRAME_THICK|FRAME_RAISED|LAYOUT_FILL_X|LAYOUT_TOP|LAYOUT_LEFT)
    spinChoreBtn.padLeft, spinChoreBtn.padRight = 10, 10
    spinChoreBtn.padTop, spinChoreBtn.padBottom = 5, 5
    spinChoreBtn.connect(SEL_COMMAND) do
      @spinning = true
      @chore = getApp().addChore(:repeat => true) do
        @angle += 2.0
        if @angle > 360.0
          @angle -= 360.0
        end
        drawScene()
      end
    end
    spinChoreBtn.connect(SEL_UPDATE) do |sender, sel, ptr|
      @spinning ? sender.disable : sender.enable
    end

    # Stop spinning
    stopBtn = FXButton.new(buttonFrame,
      "&Stop Spin\tStop this mad spinning, I'm getting dizzy",
      :opts => FRAME_THICK|FRAME_RAISED|LAYOUT_FILL_X|LAYOUT_TOP|LAYOUT_LEFT)
    stopBtn.padLeft, stopBtn.padRight = 10, 10
    stopBtn.padTop, stopBtn.padBottom = 5, 5
    stopBtn.connect(SEL_COMMAND) do
      @spinning = false
      if @timer
        getApp().removeTimeout(@timer)
        @timer = nil
      end
      if @chore
        getApp().removeChore(@chore)
        @chore = nil
      end
    end
    stopBtn.connect(SEL_UPDATE) do |sender, sel, ptr|
      @spinning ? sender.enable : sender.disable
    end

    # Exit button
    exitBtn = FXButton.new(buttonFrame, "&Exit\tExit the application", nil,
      getApp(), FXApp::ID_QUIT,
      FRAME_THICK|FRAME_RAISED|LAYOUT_FILL_X|LAYOUT_TOP|LAYOUT_LEFT)
    exitBtn.padLeft, exitBtn.padRight = 10, 10
    exitBtn.padTop, exitBtn.padBottom = 5, 5

    # Make a tooltip
    FXToolTip.new(getApp())

    # Initialize private variables
    @spinning = false
    @chore = nil
    @timer = nil
    @angle = 0.0
  end

  # Create and initialize
  def create
    super
    show(PLACEMENT_SCREEN)
  end
end

if __FILE__ == $0
  # Construct the application
  application = Fox::FXApp.new("GLTest", "FoxTest")

  # Construct the main window
  GLTestWindow.new(application)

  # Create the app's windows
  application.create

  # Run the application
  application.run
end