' Gambas class file

' texture
Private textures As New Integer[]

' Rotations & translations
Private xrot As Float
Private yrot As Float
Private zrot As Float
Private ztrans As Float = -4.5

Private initialized As Boolean = False
Private aColor As Float = 1.0
Private aFinished As Boolean = False
Private wantFading As Boolean = False

Private $eSpeed As Float

Property Read finished As Boolean

Public Sub _new(FrameRate As Integer)
  
  $eSpeed = 300 / FrameRate
  
End


Public Sub _free()

  Gl.DeleteTextures(textures)

End

Public Sub Resize(W As Integer, H As Integer)

  ' Width/Height Ratio
  Dim ratio As Float
  Dim Height As Integer

  Height = H
  ' Protect against a divide by zero
  If Height = 0 Then Height = 1

  ratio = W / Height

  ' Setup our viewport
  Gl.Viewport(0, 0, W, H)
  ' change to the projection matrix AND set our viewing volume.
  Gl.MatrixMode(Gl.PROJECTION)
  Gl.LoadIdentity()

  ' Set our perspective
  Glu.Perspective(45.0, ratio, 0.1, 10.0)

  ' Make sure we're changing the model view and not the projection
  Gl.MatrixMode(Gl.MODELVIEW)
  GL.LoadIdentity()

End

Public Sub Draw()

  If initialized = False Then initialize()
  If wantFading = True Then Me.Quit()

  Gl.Clear(Gl.COLOR_BUFFER_BIT Or Gl.DEPTH_BUFFER_BIT)

  Gl.LoadIdentity()
  Gl.Translatef(0.0, 0.0, ztrans)

  Gl.Rotatef(xrot, 1.0, 0.0, 0.0) ' Rotate On The X Axis
  Gl.Rotatef(yrot, 0.0, 1.0, 0.0) ' Rotate On The Y Axis
  Gl.Rotatef(zrot, 0.0, 0.0, 1.0) ' Rotate On The Z Axis

  ' Select our texture
  Gl.BindTexture(Gl.TEXTURE_2D, textures[0])

  Gl.Begin(Gl.QUADS)
    Gl.Colorf(aColor, aColor, aColor, 0.5)
    ' front face
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(-1.0, -1.0, 1.0)
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(1.0, -1.0, 1.0)
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(1.0, 1.0, 1.0)
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(-1.0, 1.0, 1.0)

    ' Back face
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(-1.0, -1.0, -1.0)
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(-1.0, 1.0, -1.0)
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(1.0, 1.0, -1.0)
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(1.0, -1.0, -1.0)

    ' Top face
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(-1.0, 1.0, -1.0)
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(-1.0, 1.0, 1.0)
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(1.0, 1.0, 1.0)
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(1.0, 1.0, -1.0)

    ' Bottom Face
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(-1.0, -1.0, -1.0)
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(1.0, -1.0, -1.0)
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(1.0, -1.0, 1.0)
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(-1.0, -1.0, 1.0)

    ' Right face
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(1.0, -1.0, -1.0)
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(1.0, 1.0, -1.0)
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(1.0, 1.0, 1.0)
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(1.0, -1.0, 1.0)

    ' Left face
    ' Bottom Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 1.0)
    Gl.Vertexf(-1.0, -1.0, -1.0)
    ' Bottom Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 1.0)
    Gl.Vertexf(-1.0, -1.0, 1.0)
    ' Top Right OF The Texture AND Quad
    Gl.TexCoordf(1.0, 0.0)
    Gl.Vertexf(-1.0, 1.0, 1.0)
    ' Top Left OF The Texture AND Quad
    Gl.TexCoordf(0.0, 0.0)
    Gl.Vertexf(-1.0, 1.0, -1.0)

  Gl.End()

  xrot = xrot + 0.1 * $eSpeed
  zrot = zrot + 0.1 * $eSpeed

End

Function Finished_Read() As Boolean

  Return aFinished

End

Public Sub Quit()

  aColor -= 0.01 * $eSpeed

  If wantFading = False Then wantFading = True
  If aColor < 0 Then aFinished = True

End

Private Sub Initialize()

  ' Enable texturing
  Gl.Enable(Gl.TEXTURE_2D)
  loadTextures()
  ' Enable smooth shading
  Gl.ShadeModel(Gl.SMOOTH)
  ' Set the background black
  Gl.ClearColor(0.0, 0.0, 0.0, 0.0)
  ' Depth buffer setup
  Gl.ClearDepth(1.0)
  ' Enables Depth Testing
  Gl.Enable(Gl.DEPTH_TEST)
  ' The Type OF Depth Test TO DO
  Gl.DepthFunc(Gl.LEQUAL)
  ' Really Nice Perspective Calculations
  Gl.Hint(Gl.PERSPECTIVE_CORRECTION_HINT, Gl.NICEST)
  Gl.BlendFunc(Gl.SRC_ALPHA, Gl.ONE)
  Gl.Enable(Gl.BLEND)
  Gl.Disable(Gl.DEPTH_TEST)
  initialized = True

End

Private Sub LoadTextures()

  Dim logo As Image

  logo = Image.Load("logo.png")

  textures = Gl.GenTextures(1)

  Gl.BindTexture(Gl.TEXTURE_2D, textures[0])
  Gl.TexImage2D(logo)
  Glu.Build2DMipmaps(logo)
  Gl.TexParameteri(Gl.TEXTURE_2D, Gl.TEXTURE_MIN_FILTER, Gl.LINEAR_MIPMAP_NEAREST)
  Gl.TexParameteri(Gl.TEXTURE_2D, Gl.TEXTURE_MAG_FILTER, Gl.LINEAR)

End