Microsoft Small Basic

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'Small Basic Raytracer
'by ThirdMagus
'arranged for CH4 by Nonki Takahashi
'program ID KCH420-4

Init()
LoadScene()

previewscene:
Preview()
GraphicsWindow.BrushColor = "Black"
GraphicsWindow.DrawText(10,450,"Press Enter to render image, or press Space for different scene.")
While(Space = "False" And Enter = "False")
  Program.Delay(10)
EndWhile
If(Space = "True") Then
  Space = "False"
  Enter = "False"
  RandomScene()
  Goto previewscene
EndIf

Preview()

For y=0 To 479
  For x=0 To 639
    Level = 0
    Coefficient = 1
    Red = 0
    Green = 0
    Blue = 0
    Ray["Coord"]["x"] = x
    Ray["Coord"]["y"] = y
    Ray["Coord"]["z"] = -1000
    Ray["Dir"]["x"] = 0
    Ray["Dir"]["y"] = 0
    Ray["Dir"]["z"] = 1
    While (Coefficient > 0) And (Level < 10)
      t = 2000
      FoundIndex = 0
      ObjectIndices = Array.GetAllIndices(Objects)
      IntersectRay = Ray
      For i = 1 To Array.GetItemCount(ObjectIndices)
        Object = Objects[ObjectIndices[i]]
        DetermineIntersection()
      EndFor
      If(FoundIndex > 0) Then
        Ray["Coord"]["x"] = Ray["Coord"]["x"] + Ray["Dir"]["x"] * t
        Ray["Coord"]["y"] = Ray["Coord"]["y"] + Ray["Dir"]["y"] * t
        Ray["Coord"]["z"] = Ray["Coord"]["z"] + Ray["Dir"]["z"] * t
        FoundObject = Objects[FoundIndex]
        Normalise_Vector["x"] = Ray["Coord"]["x"] - FoundObject["Coord"]["x"]
        Normalise_Vector["y"] = Ray["Coord"]["y"] - FoundObject["Coord"]["y"]
        Normalise_Vector["z"] = Ray["Coord"]["z"] - FoundObject["Coord"]["z"]
        Normalise()
        SphereNormal = Normalise_Vector
        LightIndices = Array.GetAllIndices(Lights)
        For j = 1 To Array.GetItemCount(LightIndices)
          Light = Lights[LightIndices[j]]
          LightRay["Coord"] = Ray["Coord"]
          Normalise_Vector["x"] = Light["Coord"]["x"] - Ray["Coord"]["x"]
          Normalise_Vector["y"] = Light["Coord"]["y"] - Ray["Coord"]["y"]
          Normalise_Vector["z"] = Light["Coord"]["z"] - Ray["Coord"]["z"]
          Normalise()
          LightRay["Dir"] = Normalise_Vector
          DotProduct_Vector1 = SphereNormal
          DotProduct_Vector2 = LightRay["Dir"]
          DotProduct()
          If(DotProduct_Product <= 0) Then
            Goto skiplight
          EndIf
          InShadow = "False"
          IntersectRay = LightRay
          FoundIndex = 0
          For i = 1 To Array.GetItemCount(ObjectIndices)
            Object = Objects[ObjectIndices[i]]
            DetermineIntersection()
            If(FoundIndex > 0) Then
              InShadow = "True"
            EndIf
          EndFor
          If(InShadow = "False") Then
            DotProduct_Vector1 = SphereNormal
            DotProduct_Vector2 = LightRay["Dir"]
            DotProduct()
            Lambert = DotProduct_Product * Coefficient
            Red = Red + Lambert * Light["Color"]["r"] * FoundObject["Color"]["r"]
            Green = Green + Lambert * Light["Color"]["g"] * FoundObject["Color"]["g"]
            Blue = Blue + Lambert * Light["Color"]["b"] * FoundObject["Color"]["b"]
          EndIf
          skiplight:
        EndFor
        Coefficient = Coefficient * FoundObject["Reflect"]
        DotProduct_Vector1 = Ray["Dir"]
        DotProduct_Vector2 = SphereNormal
        DotProduct()
        Reflet = 2 * DotProduct_Product
        Normalise_Vector["x"] = Ray["Dir"]["x"] - (Reflet * SphereNormal["x"])
        Normalise_Vector["y"] = Ray["Dir"]["y"] - (Reflet * SphereNormal["y"])
        Normalise_Vector["z"] = Ray["Dir"]["z"] - (Reflet * SphereNormal["z"])
        Normalise()
        Ray["Dir"] = Normalise_Vector
        Level = Level + 1
      Else
        Level = 10
      EndIf
    EndWhile

    If(Red > 1) Then
      Red = 1
    EndIf
    If(Green > 1) Then
      Green = 1
    EndIf
    If(Blue > 1) Then
      Blue = 1
    EndIf

    GraphicsWindow.SetPixel(x,y,GraphicsWindow.GetColorFromRGB(Red*255, Green*255, Blue*255))
  EndFor
EndFor

'Inititalises screen
'Input:
'Output:
Sub Init
  GraphicsWindow.Title = "CH4 by Raytracer"
  GraphicsWindow.BackgroundColor = "Gray"
  GraphicsWindow.Height = 480
  GraphicsWindow.Width = 640
  GraphicsWindow.KeyUp = OnKeyUp
  Space = "False"
  Enter = "False"
EndSub

Sub OnKeyUp
  key = GraphicsWindow.LastKey
  If (key = "Space") Then
    Space = "True"
  ElseIf (key = "Return") Then
    Enter = "True"
  EndIf
EndSub


'Inititalises scene
'Input:
'Output: Objects, Lights
Sub LoadScene
  Objects[1]["Coord"]["x"] = 320
  Objects[1]["Coord"]["y"] = 240
  Objects[1]["Coord"]["z"] = 0
  Objects[1]["Size"] = 85
  Objects[1]["Color"]["r"] = 0.1
  Objects[1]["Color"]["g"] = 0.1
  Objects[1]["Color"]["b"] = 0.1
  Objects[1]["Reflect"] = 0.2

  Objects[2]["Coord"]["x"] = 320
  Objects[2]["Coord"]["y"] = 240 - 87.5 * 2
  Objects[2]["Coord"]["z"] = 62
  Objects[2]["Size"] = 55
  Objects[2]["Color"]["r"] = 1
  Objects[2]["Color"]["g"] = 1
  Objects[2]["Color"]["b"] = 1
  Objects[2]["Reflect"] = 0.2

  Objects[3]["Coord"]["x"] = 320 - 87.5 * 2
  Objects[3]["Coord"]["y"] = 240
  Objects[3]["Coord"]["z"] = -62
  Objects[3]["Size"] = 55
  Objects[3]["Color"]["r"] = 1
  Objects[3]["Color"]["g"] = 1
  Objects[3]["Color"]["b"] = 1
  Objects[3]["Reflect"] = 0.2

  Objects[4]["Coord"]["x"] = 320 + 87.5 * 2
  Objects[4]["Coord"]["y"] = 240
  Objects[4]["Coord"]["z"] = -62
  Objects[4]["Size"] = 55
  Objects[4]["Color"]["r"] = 1
  Objects[4]["Color"]["g"] = 1
  Objects[4]["Color"]["b"] = 1
  Objects[4]["Reflect"] = 0.2

  Objects[5]["Coord"]["x"] = 320
  Objects[5]["Coord"]["y"] = 240 + 87.5 * 2
  Objects[5]["Coord"]["z"] = 62
  Objects[5]["Size"] = 55
  Objects[5]["Color"]["r"] = 1
  Objects[5]["Color"]["g"] = 1
  Objects[5]["Color"]["b"] = 1
  Objects[5]["Reflect"] = 0.2

  Lights[1]["Coord"]["x"] = 0
  Lights[1]["Coord"]["y"] = 240
  Lights[1]["Coord"]["z"] = -100
  Lights[1]["Color"]["r"] = 1
  Lights[1]["Color"]["g"] = 1
  Lights[1]["Color"]["b"] = 1

  Lights[2]["Coord"]["x"] = 640
  Lights[2]["Coord"]["y"] = 240
  Lights[2]["Coord"]["z"] = -10000
  Lights[2]["Color"]["r"] = 0.5
  Lights[2]["Color"]["g"] = 0.5
  Lights[2]["Color"]["b"] = 0.5
EndSub

'Generates a new random scene
Sub RandomScene
  Objects = ""
  ObjectCount = Math.GetRandomNumber(4) + 1
  For i=1 To ObjectCount
    Objects[i]["Coord"]["x"] = Math.GetRandomNumber(640)-1
    Objects[i]["Coord"]["y"] = Math.GetRandomNumber(480)-1
    Objects[i]["Coord"]["z"] = Math.GetRandomNumber(400)-200
    Objects[i]["Size"] = Math.GetRandomNumber(80) + 60

    Normalise_Vector["x"] = Math.GetRandomNumber(256) - 1
    Normalise_Vector["y"] = Math.GetRandomNumber(256) - 1
    Normalise_Vector["z"] = Math.GetRandomNumber(256) - 1
    Normalise()
    Objects[i]["Color"]["r"] = Normalise_Vector["x"]
    Objects[i]["Color"]["g"] = Normalise_Vector["y"]
    Objects[i]["Color"]["b"] = Normalise_Vector["z"]

    Objects[i]["Reflect"] = (Math.GetRandomNumber(10))/10

  EndFor
EndSub


'Shows a preview of what will be rendered
Sub Preview
  ObjectIndices = Array.GetAllIndices(Objects)
  'First bubblesort to object list so the objects furthest away are drawn first
  bubblesort:
  swapped = "False"
  For i = 1 To Array.GetItemCount(ObjectIndices)-1
    Object = Objects[ObjectIndices[i]]
    If(Objects[ObjectIndices[i+1]]["Coord"]["z"] > Object["Coord"]["z"]) Then
      swapped = "True"
      Objects[ObjectIndices[i]] = Objects[ObjectIndices[i+1]]
      Objects[ObjectIndices[i+1]] = Object
    EndIf
  EndFor
  If(swapped = "True") Then
    Goto bubblesort
  EndIf

  GraphicsWindow.Clear()

  For i = 1 To Array.GetItemCount(ObjectIndices)
    Object = Objects[ObjectIndices[i]]
    r = Object["Color"]["r"]*255
    g = Object["Color"]["g"]*255
    b = Object["Color"]["b"]*255
    GraphicsWindow.BrushColor = GraphicsWindow.GetColorFromRGB(r,g,b)
    x = Object["Coord"]["x"] - Object["Size"]
    y = Object["Coord"]["y"] - Object["Size"]
    GraphicsWindow.FillEllipse(x, y, Object["Size"]*2, Object["Size"]*2)
  EndFor
EndSub


'Determines if and where the ray and object intersect
'Input: IntersectRay["Coord"["x", "y", "z"], "Dir"["x", "y", "z"]], Object["Coord"["x", "y", "z"], "Size"], ObjectIndices[i]
'Output: t, FoundIndex
Sub DetermineIntersection
  Distance["x"] = Object["Coord"]["x"] - IntersectRay["Coord"]["x"]
  Distance["y"] = Object["Coord"]["y"] - IntersectRay["Coord"]["y"]
  Distance["z"] = Object["Coord"]["z"] - IntersectRay["Coord"]["z"]
  DotProduct_Vector1 = IntersectRay["Dir"]
  DotProduct_Vector2 = Distance
  DotProduct()
  B = DotProduct_Product
  DotProduct_Vector1 = Distance
  DotProduct_Vector2 = Distance
  DotProduct()
  D = B*B - DotProduct_Product + Object["Size"]*Object["Size"]
  If(D >= 0) Then
    t0 = B - Math.SquareRoot(D)
    t1 = B + Math.SquareRoot(D)

    If((t0 > 0.1) And (t0 < t)) Then
      t = t0
      FoundIndex = ObjectIndices[i]
    EndIf
    If((t1 > 0.1) And (t1 < t)) Then
      t = t1
      FoundIndex = ObjectIndices[i]
    EndIf
  EndIf
EndSub

'Calculates dot product of two vectors
'Input: DotProduct_Vector1["x", "y", "z"], DotProduct_Vector2["x", "y", "z"]
'Output: DotProduct_Product
Sub DotProduct
  DotProduct_Product = DotProduct_Vector1["x"] * DotProduct_Vector2["x"]
  DotProduct_Product = DotProduct_Product + DotProduct_Vector1["y"] * DotProduct_Vector2["y"]
  DotProduct_Product = DotProduct_Product + DotProduct_Vector1["z"] * DotProduct_Vector2["z"]
EndSub

'Normalises vector
'Input: Normalise_Vector["x", "y", "z"]
'Output: Normalise_Vector["x", "y", "z"]
Sub Normalise
  DotProduct_Vector1 = Normalise_Vector
  DotProduct_Vector2 = Normalise_Vector
  DotProduct()
  If(Math.SquareRoot(DotProduct_Product) > 0) Then
    Normalise_Vector["x"] = Normalise_Vector["x"] / Math.SquareRoot(DotProduct_Product)
    Normalise_Vector["y"] = Normalise_Vector["y"] / Math.SquareRoot(DotProduct_Product)
    Normalise_Vector["z"] = Normalise_Vector["z"] / Math.SquareRoot(DotProduct_Product)
  EndIf
EndSub
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