;
; Test example for
; PickedU(),PickedV(),PickedW() commands
;
; Created by Mikkel Fredborg
; Inspired by David Bird
;
Graphics3D 800,600
SetBuffer BackBuffer()

lit=CreateLight()
LightColor lit,60,60,60
PositionEntity lit,0,10,0
RotateEntity lit,90,0,0

cam=CreateCamera()
CameraRange cam,.1,1000
PositionEntity cam,0,0,-3
CameraClsColor cam,100,100,100

Global cubetex=CreateTexture(64,64)
; make some squares on the texture
SetBuffer TextureBuffer(cubetex)
Color 128,128,128
Rect 0,0,TextureWidth(cubetex)/2.0,TextureHeight(cubetex)/2.0,True
Rect TextureWidth(cubetex)/2.0,TextureHeight(cubetex)/2.0,(TextureWidth(cubetex)/2.0)-1,(TextureHeight(cubetex)/2.0)-1,True
SetBuffer BackBuffer()

cube = CreateCylinder(8)
PositionEntity cube,1,0,0
EntityTexture cube,cubetex,0,0
EntityPickMode cube,2

; Adjust uv coordinates of the cube to tile the texture
surf_n = CountSurfaces(cube)
For i = 1 To surf_n
   surf = GetSurface(cube,i)
   n_verts = CountVertices(surf)-1
   For j = 0 To n_verts
      VertexTexCoords surf,j,VertexU(surf,j)*1.0,VertexV(surf,j)*1.0,VertexW(surf,j)*1.0
   Next
Next

Global spheretex=CreateTexture(256,256)
sphere = CreateSphere()
PositionEntity sphere,-1,0,0
EntityTexture sphere,spheretex,0,0
EntityPickMode sphere,2

plane = CreatePlane()
PositionEntity plane,0,-2,0
EntityPickMode plane,2

Global dotred# = 0.0
Global dotgrn# = 0.0
Global dotblu# = 0.0

ang# = 0

FlushMouse



;
; PickedU(), PickedV(), PickedW() commands
;
; Created by Mikkel Fredborg
;
; Use as you please, but please include a thank you :)
;

;
; PickedTri type
; Necessary for the PickedU(), PickedV(), and PickedW() commands
Type PickedTri
   Field ent,surf,tri            ;picked entity, surface and triangle
   Field px#,py#,pz#             ;picked xyz
   Field pu#[1],  pv#[1]  ,pw#[1]  ;picked uvw x 2
   
   Field vx#[2],  vy#[2]  ,vz#[2]  ;vertex xyz
   Field vnx#[2], vny#[2] ,vnz#[2] ;vertex normals
   Field vu#[5],  vv#[5]  ,vw#[5]  ;vertex uvw x 2
End Type

Global ptri.pickedtri = New pickedtri


TurnEntity cube,-40,15,0


While Not KeyDown(1)

   xm = MouseX()
   ym = MouseY()

   If MouseDown(1) Then
      Select CameraPick(cam,xm,ym)
         Case cube:    PaintRedDot(cubetex  ,PickedU()*(TextureWidth(cubetex)-1)  ,PickedV()*(TextureHeight(cubetex)-1))
         Case sphere:  PaintRedDot(spheretex,PickedU()*(TextureWidth(spheretex)-1),PickedV()*(TextureHeight(spheretex)-1))
      End Select
   Else
      If MouseDown(2) Then
         Select CameraPick(cam,xm,ym)
            Case cube:    ReadDot(cubetex  ,PickedU()*(TextureWidth(cubetex)-1)  ,PickedV()*(TextureHeight(cubetex)-1))
            Case sphere:  ReadDot(spheretex,PickedU()*(TextureWidth(spheretex)-1),PickedV()*(TextureHeight(spheretex)-1))
         End Select
      End If
   End If
   
   ang = (ang + 0.1) Mod 360
   ;TurnEntity cube,-Sin(ang)*0.3,-Cos(ang)*0.3,0
   ;TurnEntity sphere,Sin(ang)*0.1,Cos(ang)*0.1,0
   
   UpdateWorld
   RenderWorld

   ; draw mouse cursor
   Line xm-8,ym,xm-4,ym
   Line xm+8,ym,xm+4,ym
   Line xm,ym-8,xm,ym-4
   Line xm,ym+8,xm,ym+4
   Oval xm-4,ym-4,9,9,False   

   ; write some info
   Text 0,  0,"Use left mousebutton to paint the cube and the sphere"
   Text 0, 20,"ent = "+PickedEntity()
   Text 0, 35,"surf = "+PickedSurface()
   Text 0, 50,"tri = "+PickedTriangle()
         
   Text 0, 80,"x = "+PickedX()
   Text 0, 95,"y = "+PickedY()
   Text 0,110,"z = "+PickedZ()
   
   Text 0,140,"u = "+PickedU()
   Text 0,155,"v = "+PickedV()
   Text 0,170,"w = "+PickedW()

   Text 0,200,"nx= "+PickedNX()
   Text 0,215,"ny= "+PickedNY()
   Text 0,230,"nz= "+PickedNZ()
   
   Text 14,460,"Use right mousebutton to pick up a texture color"
   Color dotred,dotgrn,dotblu
   Rect 0,460,12,12,True
   Color 255,255,255

  showtex

   Flip
Wend

ClearWorld
End


Function showtex()

 CopyRect 0,0,TextureWidth(cubetex),TextureHeight(cubetex),0,0,TextureBuffer(cubetex),BackBuffer()

 CopyRect 0,0,TextureWidth(spheretex),TextureHeight(spheretex),256,0,TextureBuffer(spheretex),BackBuffer()

End Function


;
; Plots a red dot :)
Function PaintRedDot(tex,x,y)
   SetBuffer TextureBuffer(tex)
   
   maxwidth  = TextureWidth(tex)
   maxheight = TextureHeight(tex)
   
   red# = 255
   grn# = 0
   blu# = 0
   WritePixel x,y,blu Or (grn Shl 8) Or (red Shl 16)
   
   For xx = -1 To 1
      For yy = -1 To 1
         If (xx=0) Xor (yy=0)
            If (xx<0 And x>0) Or (xx>0 And x<maxwidth) Or (yy<0 And y>0) Or (yy>0 And y<maxheight)
               argb = ReadPixel(x+xx,y+yy)
               red# =  64 + (argb Shr 16 And %11111111)
               grn# =   0 + (argb Shr 8 And %11111111)
               blu# =   0 + (argb Shr 8 And %11111111)

               If red>255 Then red = 255
               If grn>255 Then grn = 255
               If blu>255 Then blu = 255
      
               WritePixel x+xx,y+yy,blu Or (grn Shl 8) Or (red Shl 16)
            End If
         End If
      Next
   Next
   
   SetBuffer BackBuffer()
End Function

;
; Reads a pixel in a texture
Function ReadDot(tex,x,y)
   SetBuffer TextureBuffer(tex)
   
   maxwidth  = TextureWidth(tex)
   maxheight = TextureHeight(tex)
   
   If x<maxwidth And y<maxheight
      argb = ReadPixel(x,y)
      dotred# = (argb Shr 16 And %11111111)
      dotgrn# = (argb Shr 8 And %11111111)
      dotblu# = (argb Shr 8 And %11111111)
   End If
   
   SetBuffer BackBuffer()
End Function


;###################################################################################################################
;###################################################################################################################
;###################################################################################################################
;###################################################################################################################


;
; Returns the Texture U coordinate of the last successful pick command
; coordset may be set to either 0 or 1
Function PickedU#(coordset = 0)
   
   ; if something new has been picked then calculate the new uvw coordinates
   If (PickedX()<>ptri\px) Or (PickedY()<>ptri\py) Or (PickedZ()<>ptri\pz) Or (PickedSurface()<>ptri\surf)
      PickedUVW()
   End If
   
   Return ptri\pu[coordset]
   
End Function

;
; Returns the Texture U coordinate of the last successful pick command
; coordset may be set to either 0 or 1
Function PickedV#(coordset = 0)
   
   ; if something new has been picked then calculate the new uvw coordinates
   If (PickedX()<>ptri\px) Or (PickedY()<>ptri\py) Or (PickedZ()<>ptri\pz) Or (PickedSurface()<>ptri\surf)
      PickedUVW()
   End If
   
   Return ptri\pv[coordset]
   
End Function

;
; Returns the Texture U coordinate of the last successful pick command
; coordset may be set to either 0 or 1
Function PickedW#(coordset = 0)
   
   ; if something new has been picked then calculate the new uvw coordinates
   If (PickedX()<>ptri\px) Or (PickedY()<>ptri\py) Or (PickedZ()<>ptri\pz) Or (PickedSurface()<>ptri\surf)
      PickedUVW()
   End If
   
   Return ptri\pw[coordset]
   
End Function

;
; Calculates the UVW coordinates of a pick
; Do not call this by yourself, as PickedU(), PickedV(), and PickedW()
; takes care of calling it when nescessary
Function PickedUVW()

   If PickedSurface()
      ptri\ent  = PickedEntity()
      ptri\surf = PickedSurface()
      ptri\tri  = PickedTriangle()
         
      ptri\px = PickedX()
      ptri\py = PickedY()
      ptri\pz = PickedZ()
      
      For i = 0 To 2
         TFormPoint VertexX(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i)),VertexY(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i)),VertexZ(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i)),ptri\ent,0

         ptri\vx[i] = TFormedX()
         ptri\vy[i] = TFormedY()
         ptri\vz[i] = TFormedZ()

         ptri\vnx[i] = VertexNX(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i))
         ptri\vny[i] = VertexNY(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i))
         ptri\vnz[i] = VertexNZ(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i))
               
         ptri\vu[i+0] = VertexU(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),0)
         ptri\vv[i+0] = VertexV(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),0)
         ptri\vw[i+0] = VertexW(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),0)

         ptri\vu[i+3] = VertexU(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),1)
         ptri\vv[i+3] = VertexV(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),1)
         ptri\vw[i+3] = VertexW(ptri\surf,TriangleVertex(ptri\surf,ptri\tri,i),1)
      Next

      ; Select which component of xyz coordinates to ignore
      Local coords = 3

      If Abs(PickedNX()) > Abs(PickedNY())
         If Abs(PickedNX())>Abs(PickedNZ()) Then coords = 1
      Else
         If Abs(PickedNY())>Abs(PickedNZ()) Then coords = 2
      EndIf
      
      Local a0#,a1#,b0#,b1#,c0#,c1#
      
      ; xy components
      If (coords = 3)
         ; edge 0
         a0# = ptri\vx[1] - ptri\vx[0]
         a1# = ptri\vy[1] - ptri\vy[0]
      
         ; edge 1
         b0# = ptri\vx[2] - ptri\vx[0]
         b1# = ptri\vy[2] - ptri\vy[0]

         ; picked offset from triangle vertex 0
         c0# = PickedX() - ptri\vx[0]
         c1# = PickedY() - ptri\vy[0]
      Else      
         ; xz components
         If (coords = 2)
            ; edge 0
            a0# = ptri\vx[1] - ptri\vx[0]
            a1# = ptri\vz[1] - ptri\vz[0]
      
            ; edge 1
            b0# = ptri\vx[2] - ptri\vx[0]
            b1# = ptri\vz[2] - ptri\vz[0]

            ; picked offset from triangle vertex 0
            c0# = PickedX() - ptri\vx[0]
            c1# = PickedZ() - ptri\vz[0]
         Else
            ; yz components

            ; edge 0
            a0# = ptri\vy[1] - ptri\vy[0]
            a1# = ptri\vz[1] - ptri\vz[0]
      
            ; edge 1
            b0# = ptri\vy[2] - ptri\vy[0]
            b1# = ptri\vz[2] - ptri\vz[0]

            ; picked offset from triangle vertex 0
            c0# = PickedY() - ptri\vy[0]
            c1# = PickedZ() - ptri\vz[0]
         End If
      End If
                  
      ;
      ; u and v are offsets from vertex 0 along edge 0 and edge 1
      ; using these it is possible to calculate the Texture UVW coordinates
      ; of the picked XYZ location
      ;
      ; a0*u + b0*v = c0
      ; a1*u + b1*v = c1
      ;
      ; solve equation (standard equation with 2 unknown quantities)
      ; check a math book to see why the following is true
      ;
      Local u# = (c0*b1 - b0*c1) / (a0*b1 - b0*a1)
      Local v# = (a0*c1 - c0*a1) / (a0*b1 - b0*a1)
      
      ; If either u or v is out of range then the
      ; picked entity was not a mesh, and therefore
      ; the uvw coordinates cannot be calculated
      If (u<0.0 Or u>1.0) Or (v<0.0 Or v>1.0)
         Return
      End If
      
      ; Calculate picked uvw's for coordset 0 (and modulate them to be in the range of 0-1 nescessary)
      ptri\pu[0] = (ptri\vu[0] + ((ptri\vu[1] - ptri\vu[0]) * u) + ((ptri\vu[2] - ptri\vu[0]) * v)) Mod 1
      ptri\pv[0] = (ptri\vv[0] + ((ptri\vv[1] - ptri\vv[0]) * u) + ((ptri\vv[2] - ptri\vv[0]) * v)) Mod 1
      ptri\pw[0] = (ptri\vw[0] + ((ptri\vw[1] - ptri\vw[0]) * u) + ((ptri\vw[2] - ptri\vw[0]) * v)) Mod 1
      
      ; If any of the coords are negative
      If ptri\pu[0]<0.0 Then ptri\pu[0] = 1.0 + ptri\pu[0]
      If ptri\pv[0]<0.0 Then ptri\pv[0] = 1.0 + ptri\pv[0]
      If ptri\pw[0]<0.0 Then ptri\pw[0] = 1.0 + ptri\pw[0]
      
      ; Calculate picked uvw's for coordset 1 (and modulate them to be in the range of 0-1 nescessary)
      ptri\pu[1] = (ptri\vu[3] + ((ptri\vu[4] - ptri\vu[3]) * u) + ((ptri\vu[5] - ptri\vu[3]) * v)) Mod 1
      ptri\pv[1] = (ptri\vv[3] + ((ptri\vv[4] - ptri\vv[3]) * u) + ((ptri\vv[5] - ptri\vv[3]) * v)) Mod 1
      ptri\pw[1] = (ptri\vw[3] + ((ptri\vw[4] - ptri\vw[3]) * u) + ((ptri\vw[5] - ptri\vw[3]) * v)) Mod 1

      ; If any of the coords are negative
      If ptri\pu[1]<0.0 Then ptri\pu[1] = 1.0 + ptri\pu[1]
      If ptri\pv[1]<0.0 Then ptri\pv[1] = 1.0 + ptri\pv[1]
      If ptri\pw[1]<0.0 Then ptri\pw[1] = 1.0 + ptri\pw[1]
   End If

End Function