Imports Microsoft.Xna.Framework
Imports Microsoft.Xna.Framework.Input
Imports Microsoft.Xna.Framework.Graphics
Imports System.Runtime.InteropServices

Public Class Game
    Inherits Microsoft.Xna.Framework.Game

#Region "Strutture aggiuntive"
    Private Shared DoubleSize As Byte = Marshal.SizeOf(GetType(Double))

    Private Structure VertexPositionNormalColor
        Public Position As Vector3
        Public Normal As Vector3
        Public Color As Color

        Public Shared SizeInBytes As Int16 = 7 * 4
        Public Shared VertexElements() As VertexElement = New VertexElement() _
        { _
            New VertexElement(0, 0, VertexElementFormat.Vector3, _
                VertexElementMethod.Default, _
                VertexElementUsage.Position, 0), _
            New VertexElement(0, DoubleSize * 3, _
                VertexElementFormat.Color, _
                VertexElementMethod.Default, _
                VertexElementUsage.Color, 0), _
            New VertexElement(0, DoubleSize * 4, _
                VertexElementFormat.Vector3, _
                VertexElementMethod.Default, _
                VertexElementUsage.Normal, 0) _
        }
    End Structure

    Private Structure VertexPositionNormalMultitexture
        Public Position As Vector3
        Public Normal As Vector3
        Public TextureCoordinate As Vector4
        Public TextureWeight As Vector4

        Public Shared SizeInBytes As Int16 = (3 + 3 + 4 + 4) * 4
        Public Shared VertexElements As VertexElement() = New VertexElement() _
          { _
            New VertexElement(0, 0, VertexElementFormat.Vector3, _
                VertexElementMethod.Default, _
                VertexElementUsage.Position, 0), _
            New VertexElement(0, 4 * 3, _
                VertexElementFormat.Vector3, _
                VertexElementMethod.Default, _
                VertexElementUsage.Normal, 0), _
            New VertexElement(0, 4 * 6, _
                VertexElementFormat.Vector4, _
                VertexElementMethod.Default, _
                VertexElementUsage.TextureCoordinate, 0), _
            New VertexElement(0, 4 * 10, _
                VertexElementFormat.Vector4, _
                VertexElementMethod.Default, _
                VertexElementUsage.TextureCoordinate, 1) _
          }
    End Structure

    Private Structure SkyCubeFace
        Public Vertices() As VertexPositionTexture
        Public Indices() As Int32
        Public Texture As Texture2D
    End Structure
#End Region

#Region "Variabili globali"

    Private AppPath As String = _
        My.Application.Info.DirectoryPath

    Private Graphics As GraphicsDeviceManager

    'VERTICI, INDICI E BUFFER ------------------------
    Private Shader As Effect
    Private Vertices() As VertexPositionNormalMultitexture
    Private Indices() As Int32
    Private VBuffer As VertexBuffer
    Private IBuffer As IndexBuffer
    Private VDeclaration As VertexDeclaration
    Private SDeclaration As VertexDeclaration

    'MATRICI -----------------------------------------
    Private ViewMatrix As Matrix
    Private ProjectionMatrix As Matrix
    Private WorldMatrix As Matrix


    'HEIGHTDATA --------------------------------------
    Private HeightData(,) As Single
    Private Const MinHeight As Single = 0
    Private Const MaxHeight As Single = 30
    Private TerrainWidth, TerrainLength As Int32

    'TELECAMERA -------------------------------------
    Private PrevMouseState As MouseState
    Private LeftRightRotation As Single = MathHelper.PiOver2
    Private UpDownRotation As Single = -MathHelper.Pi / 10.0F
    Private CameraPosition As Vector3
    Private RotationSpeed As Single = 0.3
    Private MoveSpeed As Single = 1

    'TEXTURE ----------------------------------------
    Private Grass As Texture2D
    Private Sand As Texture2D
    Private Rock As Texture2D
    Private Snow As Texture2D

    'CIELO ------------------------------------------
    Private SkyFaces(4) As Texture2D
    Private SkyCube(4) As SkyCubeFace

    'ACQUA ------------------------------------------
    Private WaterHeight As Single = 5.0
    Private RefractionTarget As RenderTarget2D
    Private RefractionMap As Texture2D
    Private ReflectionTarget As RenderTarget2D
    Private ReflectionMap As Texture2D
#End Region

#Region "Funzioni utili"

    Private Function GetEffect(ByVal FileName As String) As Effect
        Dim CompEffect As CompiledEffect = _
            Effect.CompileEffectFromFile(FileName, _
            Nothing, Nothing, _
            CompilerOptions.None, _
            TargetPlatform.Windows)

        Return New Effect(Me.GraphicsDevice, _
            CompEffect.GetEffectCode, _
            CompilerOptions.None, Nothing)
    End Function

    Private Function GetTexture(ByVal FileName As String)
        Return Texture2D.FromFile(Me.GraphicsDevice, FileName)
    End Function

#End Region

#Region "Caricamento Heightmap"

    Private Sub LoadHeightMap(ByVal HeightMap As Texture2D)
        TerrainWidth = HeightMap.Width
        TerrainLength = HeightMap.Height

        Dim Colors(TerrainWidth * TerrainLength - 1) As Color
        HeightMap.GetData(Colors)

        For I As Int32 = 0 To TerrainWidth - 1
            ReDim HeightData(I, TerrainLength - 1)
        Next

        For X As Int32 = 0 To TerrainWidth - 1
            For Z As Int32 = 0 To TerrainLength - 1
                HeightData(X, Z) = MinHeight + _
                    (Colors(X + Z * TerrainWidth).R / 255) * _
                    (MaxHeight - MinHeight)
            Next
        Next

        VDeclaration = New VertexDeclaration(Me.GraphicsDevice, _
            VertexPositionNormalMultitexture.VertexElements)
    End Sub

    Private Sub SetVertices()
        ReDim Vertices(TerrainWidth * TerrainLength - 1)

        Dim Strip As Single = (MaxHeight - MinHeight) / 4
        For X As Int32 = 0 To TerrainWidth - 1
            For Z As Int32 = 0 To TerrainLength - 1
                With Vertices(X + Z * TerrainWidth)
                    Dim Y As Single = HeightData(X, Z)

                    .Position = New Vector3(X, Y, -Z)
                    .TextureCoordinate.X = X / 32
                    .TextureCoordinate.Y = Z / 32

                    .TextureWeight.X = MathHelper.Clamp(1.0F - Math.Abs(Y - 0) / 8.0F, 0, 1)
                    .TextureWeight.Y = MathHelper.Clamp(1.0F - Math.Abs(Y - 12) / 6.0F, 0, 1)
                    .TextureWeight.Z = MathHelper.Clamp(1.0F - Math.Abs(Y - 20) / 6.0F, 0, 1)
                    .TextureWeight.W = MathHelper.Clamp(1.0F - Math.Abs(Y - 30) / 6.0F, 0, 1)

                    Dim Total As Single = .TextureWeight.X
                    Total += .TextureWeight.Y
                    Total += .TextureWeight.Z
                    Total += .TextureWeight.W

                    .TextureWeight.X /= Total
                    .TextureWeight.Y /= Total
                    .TextureWeight.Z /= Total
                    .TextureWeight.W /= Total
                End With
            Next
        Next
    End Sub

    Private Sub SetIndices()
        ReDim Indices((TerrainWidth - 1) * (TerrainLength - 1) * 6 - 1)

        Dim Counter As Int32 = 0

        For X As Int32 = 0 To TerrainWidth - 2
            For Z As Int32 = 0 To TerrainLength - 2
                Dim LowerLeft As Int16 = X + Z * TerrainWidth
                Dim LowerRight As Int16 = (X + 1) + Z * TerrainWidth
                Dim TopLeft As Int16 = X + (Z + 1) * TerrainWidth
                Dim TopRight As Int16 = (X + 1) + (Z + 1) * TerrainWidth

                Indices(Counter) = TopLeft
                Indices(Counter + 1) = LowerRight
                Indices(Counter + 2) = LowerLeft
                Counter += 3

                Indices(Counter) = TopLeft
                Indices(Counter + 1) = TopRight
                Indices(Counter + 2) = LowerRight
                Counter += 3
            Next
        Next
    End Sub

    Private Sub SetNormals()
        For I As Int32 = 0 To Vertices.Length - 1
            Vertices(I).Normal = New Vector3(0, 0, 0)
        Next

        For I As Int16 = 0 To (Indices.Length / 3) - 1
            Dim Index1 As Int16 = Indices(I * 3)
            Dim Index2 As Int16 = Indices(I * 3 + 1)
            Dim Index3 As Int16 = Indices(I * 3 + 2)

            Dim Side1 As Vector3 = _
                Vertices(Index1).Position - Vertices(Index3).Position
            Dim Side2 As Vector3 = _
                Vertices(Index1).Position - Vertices(Index2).Position
            Dim Normal As Vector3 = Vector3.Cross(Side1, Side2)

            Vertices(Index1).Normal += Normal
            Vertices(Index2).Normal += Normal
            Vertices(Index3).Normal += Normal
        Next

        For Each V As VertexPositionNormalMultitexture In Vertices
            V.Normal.Normalize()
        Next
    End Sub

    Private Sub CopyToBuffer()
        VBuffer = New VertexBuffer(Me.GraphicsDevice, _
            Vertices.Length * VertexPositionNormalMultitexture.SizeInBytes, _
            BufferUsage.WriteOnly)
        VBuffer.SetData(Vertices)

        IBuffer = New IndexBuffer(Me.GraphicsDevice, _
            GetType(Int32), Indices.Length, BufferUsage.WriteOnly)
        IBuffer.SetData(Indices)

        Me.GraphicsDevice.Indices = IBuffer
        Me.GraphicsDevice.Vertices(0).SetSource( _
            VBuffer, 0, VertexPositionNormalMultitexture.SizeInBytes)
    End Sub

#End Region

#Region "Cielo"

    Private Function GetElements(Of T)(ByVal Sources() As T, ByVal ParamArray Indices() As Int32) As T()
        Dim Result(Indices.Length - 1) As T

        For I As Int16 = 0 To Indices.Length - 1
            Result(I) = Sources(Indices(I))
        Next

        Return Result
    End Function

    Private Sub LoadSkyDome()
        Dim SkyVertices(7) As VertexPositionTexture
        Dim HalfSize As Int16 = 200
        Dim HalfHeight As Int16 = 150

        SkyVertices(0).Position = New Vector3(-HalfSize, 200, HalfSize)
        SkyVertices(1).Position = New Vector3(-HalfSize, 200, -HalfSize)
        SkyVertices(2).Position = New Vector3(HalfSize, 200, HalfSize)
        SkyVertices(3).Position = New Vector3(HalfSize, 200, -HalfSize)

        SkyVertices(4).Position = New Vector3(-HalfSize, 0, HalfSize)
        SkyVertices(5).Position = New Vector3(-HalfSize, 0, -HalfSize)

        SkyVertices(6).Position = New Vector3(HalfSize, 0, HalfSize)
        SkyVertices(7).Position = New Vector3(HalfSize, 0, -HalfSize)

        SkyCube(0).Vertices = GetElements(SkyVertices, 0, 1, 2, 3)
        SkyCube(1).Vertices = GetElements(SkyVertices, 5, 1, 4, 0)
        SkyCube(2).Vertices = GetElements(SkyVertices, 4, 0, 6, 2)
        SkyCube(3).Vertices = GetElements(SkyVertices, 6, 2, 7, 3)
        SkyCube(4).Vertices = GetElements(SkyVertices, 7, 3, 5, 1)

        With SkyCube(0)
            .Indices = New Int32() {0, 1, 2, 2, 1, 3}
            .Texture = SkyFaces(0)
            .Vertices(0).TextureCoordinate = New Vector2(0, 1)
            .Vertices(1).TextureCoordinate = New Vector2(0, 0)
            .Vertices(2).TextureCoordinate = New Vector2(1, 1)
            .Vertices(3).TextureCoordinate = New Vector2(1, 0)
        End With
        For I As Byte = 1 To 4
            With SkyCube(I)
                .Indices = New Int32() {0, 1, 2, 2, 1, 3}
                .Texture = SkyFaces(I)
                .Vertices(0).TextureCoordinate = New Vector2(0, 0.5)
                .Vertices(1).TextureCoordinate = New Vector2(0, 0)
                .Vertices(2).TextureCoordinate = New Vector2(1, 0.5)
                .Vertices(3).TextureCoordinate = New Vector2(1, 0)
            End With
        Next

        SDeclaration = New VertexDeclaration(Me.GraphicsDevice, VertexPositionTexture.VertexElements)
    End Sub

    Private Sub DrawSky()
        Dim Prev As CullMode = Me.GraphicsDevice.RenderState.CullMode
        Me.GraphicsDevice.RenderState.CullMode = CullMode.None
        For I As Byte = 0 To 4
            Shader.CurrentTechnique = Shader.Techniques("Textured")
            Shader.Parameters("View").SetValue(ViewMatrix)
            Shader.Parameters("Projection").SetValue(ProjectionMatrix)
            Shader.Parameters("World").SetValue(Matrix.Identity)
            Shader.Parameters("LightEnabled").SetValue(False)
            Shader.Parameters("ATexture").SetValue(SkyFaces(I))

            Shader.Begin()
            For Each Pass As EffectPass In Shader.CurrentTechnique.Passes
                Pass.Begin()
                With Me.GraphicsDevice
                    .VertexDeclaration = SDeclaration
                    .DrawUserIndexedPrimitives(PrimitiveType.TriangleList, SkyCube(I).Vertices, 0, SkyCube(I).Vertices.Length, SkyCube(I).Indices, 0, SkyCube(I).Indices.Length / 3)
                End With
                Pass.End()
            Next
            Shader.End()
        Next
        Me.GraphicsDevice.RenderState.CullMode = Prev
    End Sub

#End Region

#Region "Acqua"

    Private Function CreatePlane(ByVal Height As Single, _
        ByVal Normal As Vector3, ByVal ClipAbove As Boolean)
        Normal.Normalize()

        Dim PlaneCoef As New Vector4(Normal, Height)
        Dim HSMatrix As Matrix = _
            Matrix.Transpose( _
            Matrix.Invert(ViewMatrix * ProjectionMatrix))

        If ClipAbove Then
            PlaneCoef *= -1
        End If
        PlaneCoef = Vector4.Transform(PlaneCoef, HSMatrix)

        Return New Plane(PlaneCoef)
    End Function

    Private Sub DrawRefractionMap()
        Dim RefractionPlane As Plane = _
            CreatePlane(WaterHeight + 1.5, New Vector3(0, -1, 0), False)
        Me.GraphicsDevice.ClipPlanes(0).Plane = RefractionPlane
        Me.GraphicsDevice.ClipPlanes(0).IsEnabled = True
        Me.GraphicsDevice.SetRenderTarget(0, RefractionTarget)
        Me.GraphicsDevice.Clear(ClearOptions.Target Or ClearOptions.DepthBuffer, Color.Black, 1.0F, 0)
        DrawTerrain()
        Me.GraphicsDevice.ClipPlanes(0).IsEnabled = False

        Me.GraphicsDevice.SetRenderTarget(0, Nothing)
        RefractionMap = RefractionTarget.GetTexture()
        Me.GraphicsDevice.Clear(Color.CornflowerBlue)
    End Sub

    Private Sub DrawReflectionMap()
        Dim Rotation As Matrix = _
            Matrix.CreateRotationX(UpDownRotation) * _
            Matrix.CreateRotationY(LeftRightRotation)
        Dim Forward As New Vector3(0, 0, -1)
        Dim Right As New Vector3(1, 0, 0)

        Dim TargetPos As Vector3 = _
            CameraPosition + Vector3.Transform(Forward, Rotation)

        Dim ReflectionPos As Vector3 = CameraPosition
        Dim ReflectionTargetPos As Vector3 = TargetPos
        ReflectionPos.Y = 2 * WaterHeight - ReflectionPos.Y
        ReflectionTargetPos.Y = 2 * WaterHeight - ReflectionTargetPos.Y

        Dim ReflectionUp As Vector3 = Vector3.Cross( _
            Vector3.Transform(Right, Rotation), ReflectionTargetPos - ReflectionPos)
        Dim ReflectionView As Matrix = Matrix.CreateLookAt( _
            ReflectionPos, ReflectionTargetPos, ReflectionUp)

        Dim OldView As Matrix = ViewMatrix

        ViewMatrix = ReflectionView
        Dim ReflectionPlane As Plane = _
            CreatePlane(WaterHeight - 0.5, New Vector3(0, -1, 0), True)
        Me.GraphicsDevice.ClipPlanes(0).Plane = ReflectionPlane
        Me.GraphicsDevice.ClipPlanes(0).IsEnabled = True
        Me.GraphicsDevice.SetRenderTarget(0, ReflectionTarget)
        Me.GraphicsDevice.Clear(ClearOptions.Target Or _
            ClearOptions.DepthBuffer, Color.Black, 1.0F, 0)
        DrawTerrain()
        DrawSky()
        Me.GraphicsDevice.ClipPlanes(0).IsEnabled = False

        Me.GraphicsDevice.SetRenderTarget(0, Nothing)
        ReflectionMap = ReflectionTarget.GetTexture()
        Me.GraphicsDevice.Clear(Color.CornflowerBlue)

        ViewMatrix = OldView
    End Sub

#End Region

#Region "Gestione telecamera"

    Private Sub ProcessMouseInput(ByVal ElapsedTime As Single)
        Dim CurrentMouseState As MouseState = Mouse.GetState

        If CurrentMouseState <> PrevMouseState Then
            Dim DX As Single = _
                CurrentMouseState.X - PrevMouseState.X
            Dim DY As Single = _
                CurrentMouseState.Y - PrevMouseState.Y

            LeftRightRotation -= DX * RotationSpeed * ElapsedTime
            UpDownRotation -= DY * RotationSpeed * ElapsedTime

            Mouse.SetPosition(Me.GraphicsDevice.Viewport.Width / 2, _
                Me.GraphicsDevice.Viewport.Height / 2)
            UpdateView()
        End If
    End Sub

    Private Sub ProcessKeyboardInput()
        Dim Motion As New Vector3(0, 0, 0)
        Dim KeyState As KeyboardState = Keyboard.GetState

        If KeyState.IsKeyDown(Keys.W) Then
            Motion += New Vector3(0, 0, -1)
        End If

        If KeyState.IsKeyDown(Keys.S) Then
            Motion += New Vector3(0, 0, 1)
        End If

        If KeyState.IsKeyDown(Keys.D) Then
            Motion += New Vector3(1, 0, 0)
        End If

        If KeyState.IsKeyDown(Keys.A) Then
            Motion += New Vector3(-1, 0, 0)
        End If

        If KeyState.IsKeyDown(Keys.Up) Then
            Motion += New Vector3(0, 1, 0)
        End If

        If KeyState.IsKeyDown(Keys.Down) Then
            Motion += New Vector3(0, -1, 0)
        End If

        UpdatePosition(Motion)
    End Sub

    Private Sub UpdateView()
        Dim Rotation As Matrix = _
            Matrix.CreateRotationX(UpDownRotation) * _
            Matrix.CreateRotationY(LeftRightRotation)

        Dim Forward As New Vector3(0, 0, -1)
        Dim Up As New Vector3(0, 1, 0)

        Dim RotForward As Vector3 = _
            Vector3.Transform(Forward, Rotation)
        Dim RotUp As Vector3 = Vector3.Transform(Up, Rotation)

        Dim Target As Vector3 = CameraPosition + RotForward
        ViewMatrix = Matrix.CreateLookAt(CameraPosition, Target, RotUp)
    End Sub

    Private Sub UpdatePosition(ByVal Motion As Vector3)
        Dim Rotation As Matrix = _
            Matrix.CreateRotationX(UpDownRotation) * _
            Matrix.CreateRotationY(LeftRightRotation)
        Dim RotMotion As Vector3 = Vector3.Transform(Motion, Rotation)

        CameraPosition += RotMotion * MoveSpeed
        UpdateView()
    End Sub

#End Region

#Region "Gestione risorse"

    Sub New()
        Me.Graphics = New GraphicsDeviceManager(Me)
        Me.Content.RootDirectory = "content"
    End Sub

    Protected Overrides Sub Initialize()
        MyBase.Initialize()
    End Sub

    Protected Overrides Sub LoadContent()
        Shader = GetEffect(AppPath & "\SimpleShader.fx")
        Grass = GetTexture(AppPath & "\grass.dds")
        Sand = GetTexture(AppPath & "\sand.dds")
        Rock = GetTexture(AppPath & "\rock.dds")
        Snow = GetTexture(AppPath & "\snow.dds")

        For I As Byte = 0 To 4
            SkyFaces(I) = GetTexture(AppPath & "\skyface" & (I + 1) & ".png")
        Next

        Dim Params As PresentationParameters = _
            Me.GraphicsDevice.PresentationParameters

        RefractionTarget = New RenderTarget2D(Me.GraphicsDevice, _
            Params.BackBufferWidth, Params.BackBufferHeight, 1, _
            Me.GraphicsDevice.DisplayMode.Format)

        ReflectionTarget = New RenderTarget2D(Me.GraphicsDevice, _
            Params.BackBufferWidth, Params.BackBufferHeight, 1, _
            Me.GraphicsDevice.DisplayMode.Format)

        LoadHeightMap(GetTexture(AppPath & "\HeightMap.bmp"))
        LoadSkyDome()
        SetVertices()
        SetIndices()
        SetNormals()
        CopyToBuffer()

        ProjectionMatrix = Matrix.CreatePerspectiveFieldOfView( _
            MathHelper.PiOver4, _
            Me.GraphicsDevice.Viewport.AspectRatio, _
            1, 500)

        CameraPosition = New Vector3(0, 40, TerrainLength / 2)
        Mouse.SetPosition(Me.GraphicsDevice.Viewport.Width / 2, _
                Me.GraphicsDevice.Viewport.Height / 2)
        PrevMouseState = Mouse.GetState
        UpdateView()

        MyBase.LoadContent()
    End Sub

    Protected Overrides Sub UnloadContent()
        MyBase.UnloadContent()
    End Sub

#End Region

#Region "Aggiornamento mondo 3D"

    Private Sub DrawTerrain()
        Shader.CurrentTechnique = Shader.Techniques("MultiTextured")

        Shader.Parameters("View").SetValue(ViewMatrix)
        Shader.Parameters("Projection").SetValue(ProjectionMatrix)
        Shader.Parameters("World").SetValue( _
            Matrix.CreateTranslation( _
            New Vector3(-TerrainWidth / 2, 0, TerrainLength / 2)))

        Dim LightDirection As New Vector3(27.73, -17.67, 6.14)
        LightDirection.Normalize()
        Shader.Parameters("LightEnabled").SetValue(True)
        Shader.Parameters("LightDirection").SetValue(LightDirection)
        Shader.Parameters("AmbientFactor").SetValue(0.3F)

        Shader.Parameters("Texture0").SetValue(Sand)
        Shader.Parameters("Texture1").SetValue(Grass)
        Shader.Parameters("Texture2").SetValue(Rock)
        Shader.Parameters("Texture3").SetValue(Snow)

        Shader.Begin()
        For Each Pass As EffectPass In Shader.CurrentTechnique.Passes
            Pass.Begin()
            With Me.GraphicsDevice
                .VertexDeclaration = VDeclaration
                Me.GraphicsDevice.DrawIndexedPrimitives( _
                    PrimitiveType.TriangleList, 0, 0, _
                    Vertices.Length, 0, Indices.Length / 3)
            End With
            Pass.End()
        Next
        Shader.End()
    End Sub

    Protected Overrides Sub Update(ByVal GameTime As GameTime)
        ProcessMouseInput(GameTime.ElapsedGameTime.TotalSeconds)
        ProcessKeyboardInput()

        If k.IsKeyDown(Keys.M) Then
            ReflectionMap.Save("prova.jpg", ImageFileFormat.Jpg)
            Me.Exit()
        End If

        MyBase.Update(GameTime)
    End Sub

    Protected Overrides Sub Draw(ByVal gameTime As GameTime)
        Me.Graphics.GraphicsDevice.Clear(Color.CornflowerBlue)

        DrawRefractionMap()
        DrawReflectionMap()

        DrawSky()
        Me.CopyToBuffer()
        DrawTerrain()

        MyBase.Draw(gameTime)
    End Sub
#End Region
End Class