[bb] PickedU(), PickedV(), PickedW() by fredborg [ 1+ years ago ]

[BlitzBot]

Title : PickedU(), PickedV(), PickedW()
Author : fredborg
Posted : 1+ years ago

Description : A nice way to retrieve the texture coordinates of a pick (ex. CameraPick and LinePick).

Usage:
PickedU([coordset]) - Returns the U component of the last successful pick command. Coordset can be either 0 or 1 depending on which texture coord set you wish to get (defaults to 0).
PickedV([coordset]) - Returns the V component
PickedW([coordset]) - Returns the W component

Includes a small test program located at the bottom of the code, so you can see how it's used (if you hadn't figured it out by now

Update: Example now shows how to retrieve a pixel color from a texture!

Limitation: This set of commands are not affected by the use of 'ScaleTexture', 'PositionTexture', or 'RotateTexture'. You have to make your own calculations, if you have used any of these commands!!!

Use as you please, but please include a mention/thanks to me

Code :

Code: BlitzBasic

1. ;
2. ; PickedU(), PickedV(), PickedW() commands
3. ;
4. ; Created by Mikkel Fredborg
5. ;
6. ; Use as you please, but please include a thank you :)
7. ;
8.  
9. ;
10. ; PickedTri type
11. ; Necessary for the PickedU(), PickedV(), and PickedW() commands
12. Type PickedTri
13.         Field ent,surf,tri                              ;picked entity, surface and triangle
14.         Field px#,py#,pz#                           ;picked xyz
15.         Field pu#[1],  pv#[1]  ,pw#[1]  ;picked uvw x 2
16.        
17.         Field vx#[2],  vy#[2]  ,vz#[2]  ;vertex xyz
18.         Field vnx#[2], vny#[2] ,vnz#[2] ;vertex normals
19.         Field vu#[5],  vv#[5]  ,vw#[5]  ;vertex uvw x 2
20. End Type
21.  
22. Global ptri.pickedtri = New pickedtri
23.  
24. ;
25. ; Returns the Texture U coordinate of the last successful pick command
26. ; coordset may be set to either 0 or 1
27. Function PickedU#(coordset = 0)
28.        
29.         ; if something new has been picked then calculate the new uvw coordinates
30.         If (PickedX()<>ptripx) Or (PickedY()<>ptripy) Or (PickedZ()<>ptripz) Or (PickedSurface()<>ptrisurf)
31.                 PickedUVW()
32.         End If
33.        
34.         Return ptripu[coordset]
35.        
36. End Function
37.  
38. ;
39. ; Returns the Texture U coordinate of the last successful pick command
40. ; coordset may be set to either 0 or 1
41. Function PickedV#(coordset = 0)
42.        
43.         ; if something new has been picked then calculate the new uvw coordinates
44.         If (PickedX()<>ptripx) Or (PickedY()<>ptripy) Or (PickedZ()<>ptripz) Or (PickedSurface()<>ptrisurf)
45.                 PickedUVW()
46.         End If
47.        
48.         Return ptripv[coordset]
49.        
50. End Function
51.  
52. ;
53. ; Returns the Texture U coordinate of the last successful pick command
54. ; coordset may be set to either 0 or 1
55. Function PickedW#(coordset = 0)
56.        
57.         ; if something new has been picked then calculate the new uvw coordinates
58.         If (PickedX()<>ptripx) Or (PickedY()<>ptripy) Or (PickedZ()<>ptripz) Or (PickedSurface()<>ptrisurf)
59.                 PickedUVW()
60.         End If
61.        
62.         Return ptripw[coordset]
63.        
64. End Function
65.  
66. ;
67. ; Calculates the UVW coordinates of a pick
68. ; Do not call this by yourself, as PickedU(), PickedV(), and PickedW()
69. ; takes care of calling it when nescessary
70. Function PickedUVW()
71.  
72.         If PickedSurface()
73.                 ptrient  = PickedEntity()
74.                 ptrisurf = PickedSurface()
75.                 ptri    ri  = PickedTriangle()
76.                        
77.                 ptripx = PickedX()
78.                 ptripy = PickedY()
79.                 ptripz = PickedZ()
80.                
81.                 For i = 0 To 2
82.                         TFormPoint VertexX(ptrisurf,TriangleVertex(ptrisurf,ptri        ri,i)),VertexY(ptrisurf,TriangleVertex(ptrisurf,ptri    ri,i)),VertexZ(ptrisurf,TriangleVertex(ptrisurf,ptri    ri,i)),ptrient,0
83.  
84.                         ptrivx[i] = TFormedX()
85.                         ptrivy[i] = TFormedY()
86.                         ptrivz[i] = TFormedZ()
87.  
88.                         ptrivnx[i] = VertexNX(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i))
89.                         ptrivny[i] = VertexNY(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i))
90.                         ptrivnz[i] = VertexNZ(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i))
91.                                        
92.                         ptrivu[i+0] = VertexU(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),0)
93.                         ptrivv[i+0] = VertexV(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),0)
94.                         ptrivw[i+0] = VertexW(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),0)
95.  
96.                         ptrivu[i+3] = VertexU(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),1)
97.                         ptrivv[i+3] = VertexV(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),1)
98.                         ptrivw[i+3] = VertexW(ptrisurf,TriangleVertex(ptrisurf,ptri     ri,i),1)
99.                 Next
100.  
101.                 ; Select which component of xyz coordinates to ignore
102.                 Local coords = 3
103.  
104.                 If Abs(PickedNX()) > Abs(PickedNY())
105.                         If Abs(PickedNX())>Abs(PickedNZ()) Then coords = 1
106.                 Else
107.                         If Abs(PickedNY())>Abs(PickedNZ()) Then coords = 2
108.                 EndIf
109.                
110.                 Local a0#,a1#,b0#,b1#,c0#,c1#
111.                
112.                 ; xy components
113.                 If (coords = 3)
114.                         ; edge 0
115.                         a0# = ptrivx[1] - ptrivx[0]
116.                         a1# = ptrivy[1] - ptrivy[0]
117.                
118.                         ; edge 1
119.                         b0# = ptrivx[2] - ptrivx[0]
120.                         b1# = ptrivy[2] - ptrivy[0]
121.  
122.                         ; picked offset from triangle vertex 0
123.                         c0# = PickedX() - ptrivx[0]
124.                         c1# = PickedY() - ptrivy[0]
125.                 Else           
126.                         ; xz components
127.                         If (coords = 2)
128.                                 ; edge 0
129.                                 a0# = ptrivx[1] - ptrivx[0]
130.                                 a1# = ptrivz[1] - ptrivz[0]
131.                
132.                                 ; edge 1
133.                                 b0# = ptrivx[2] - ptrivx[0]
134.                                 b1# = ptrivz[2] - ptrivz[0]
135.  
136.                                 ; picked offset from triangle vertex 0
137.                                 c0# = PickedX() - ptrivx[0]
138.                                 c1# = PickedZ() - ptrivz[0]
139.                         Else
140.                                 ; yz components
141.  
142.                                 ; edge 0
143.                                 a0# = ptrivy[1] - ptrivy[0]
144.                                 a1# = ptrivz[1] - ptrivz[0]
145.                
146.                                 ; edge 1
147.                                 b0# = ptrivy[2] - ptrivy[0]
148.                                 b1# = ptrivz[2] - ptrivz[0]
149.  
150.                                 ; picked offset from triangle vertex 0
151.                                 c0# = PickedY() - ptrivy[0]
152.                                 c1# = PickedZ() - ptrivz[0]
153.                         End If
154.                 End If
155.                                                
156.                 ;
157.                 ; u and v are offsets from vertex 0 along edge 0 and edge 1
158.                 ; using these it is possible to calculate the Texture UVW coordinates
159.                 ; of the picked XYZ location
160.                 ;
161.                 ; a0*u + b0*v = c0
162.                 ; a1*u + b1*v = c1
163.                 ;
164.                 ; solve equation (standard equation with 2 unknown quantities)
165.                 ; check a math book to see why the following is true
166.                 ;
167.                 Local u# = (c0*b1 - b0*c1) / (a0*b1 - b0*a1)
168.                 Local v# = (a0*c1 - c0*a1) / (a0*b1 - b0*a1)
169.                
170.                 ; If either u or v is out of range then the
171.                 ; picked entity was not a mesh, and therefore
172.                 ; the uvw coordinates cannot be calculated
173.                 If (u<0.0 Or u>1.0) Or (v<0.0 Or v>1.0)
174.                         Return
175.                 End If
176.                
177.                 ; Calculate picked uvw's for coordset 0 (and modulate them to be in the range of 0-1 nescessary)
178.                 ptripu[0] = (ptrivu[0] + ((ptrivu[1] - ptrivu[0]) * u) + ((ptrivu[2] - ptrivu[0]) * v)) Mod 1
179.                 ptripv[0] = (ptrivv[0] + ((ptrivv[1] - ptrivv[0]) * u) + ((ptrivv[2] - ptrivv[0]) * v)) Mod 1
180.                 ptripw[0] = (ptrivw[0] + ((ptrivw[1] - ptrivw[0]) * u) + ((ptrivw[2] - ptrivw[0]) * v)) Mod 1
181.                
182.                 ; If any of the coords are negative
183.                 If ptripu[0]<0.0 Then ptripu[0] = 1.0 + ptripu[0]
184.                 If ptripv[0]<0.0 Then ptripv[0] = 1.0 + ptripv[0]
185.                 If ptripw[0]<0.0 Then ptripw[0] = 1.0 + ptripw[0]
186.                
187.                 ; Calculate picked uvw's for coordset 1 (and modulate them to be in the range of 0-1 nescessary)
188.                 ptripu[1] = (ptrivu[3] + ((ptrivu[4] - ptrivu[3]) * u) + ((ptrivu[5] - ptrivu[3]) * v)) Mod 1
189.                 ptripv[1] = (ptrivv[3] + ((ptrivv[4] - ptrivv[3]) * u) + ((ptrivv[5] - ptrivv[3]) * v)) Mod 1
190.                 ptripw[1] = (ptrivw[3] + ((ptrivw[4] - ptrivw[3]) * u) + ((ptrivw[5] - ptrivw[3]) * v)) Mod 1
191.  
192.                 ; If any of the coords are negative
193.                 If ptripu[1]<0.0 Then ptripu[1] = 1.0 + ptripu[1]
194.                 If ptripv[1]<0.0 Then ptripv[1] = 1.0 + ptripv[1]
195.                 If ptripw[1]<0.0 Then ptripw[1] = 1.0 + ptripw[1]
196.         End If
197.  
198. End Function
199.  
200.  
201.  
202.  
203. ;
204. ; Test example for
205. ; PickedU(),PickedV(),PickedW() commands
206. ;
207. ; Created by Mikkel Fredborg
208. ; Inspired by David Bird
209. ;
210. Graphics3D 640,480
211. SetBuffer BackBuffer()
212.  
213. lit=CreateLight()
214. LightColor lit,60,60,60
215. PositionEntity lit,0,10,0
216. RotateEntity lit,90,0,0
217.  
218. cam=CreateCamera()
219. CameraRange cam,.1,1000
220. PositionEntity cam,0,0,-3
221. CameraClsColor cam,100,100,100
222.  
223. cubetex=CreateTexture(64,64)
224. ; make some squares on the texture
225. SetBuffer TextureBuffer(cubetex)
226. Color 128,128,128
227. Rect 0,0,TextureWidth(cubetex)/2.0,TextureHeight(cubetex)/2.0,True
228. Rect TextureWidth(cubetex)/2.0,TextureHeight(cubetex)/2.0,(TextureWidth(cubetex)/2.0)-1,(TextureHeight(cubetex)/2.0)-1,True
229. SetBuffer BackBuffer()
230.  
231. cube = CreateCube()
232. PositionEntity cube,1,0,0
233. EntityTexture cube,cubetex,0,0
234. EntityPickMode cube,2
235.  
236. ; Adjust uv coordinates of the cube to tile the texture
237. surf_n = CountSurfaces(cube)
238. For i = 1 To surf_n
239.         surf = GetSurface(cube,i)
240.         n_verts = CountVertices(surf)-1
241.         For j = 0 To n_verts
242.                 VertexTexCoords surf,j,VertexU(surf,j)*5.0,VertexV(surf,j)*5.0,VertexW(surf,j)*5.0
243.         Next
244. Next
245.  
246. spheretex=CreateTexture(256,256)
247. sphere = CreateSphere()
248. PositionEntity sphere,-1,0,0
249. EntityTexture sphere,spheretex,0,0
250. EntityPickMode sphere,2
251.  
252. plane = CreatePlane()
253. PositionEntity plane,0,-2,0
254. EntityPickMode plane,2
255.  
256. Global dotred# = 0.0
257. Global dotgrn# = 0.0
258. Global dotblu# = 0.0
259.  
260. ang# = 0
261. While Not KeyDown(1)
262.  
263.         xm = MouseX()
264.         ym = MouseY()
265.  
266.         If MouseDown(1) Then
267.                 Select CameraPick(cam,xm,ym)
268.                         Case cube:    PaintRedDot(cubetex  ,PickedU()*(TextureWidth(cubetex)-1)  ,PickedV()*(TextureHeight(cubetex)-1))
269.                         Case sphere:  PaintRedDot(spheretex,PickedU()*(TextureWidth(spheretex)-1),PickedV()*(TextureHeight(spheretex)-1))
270.                 End Select
271.         Else
272.                 If MouseDown(2) Then
273.                         Select CameraPick(cam,xm,ym)
274.                                 Case cube:    ReadDot(cubetex  ,PickedU()*(TextureWidth(cubetex)-1)  ,PickedV()*(TextureHeight(cubetex)-1))
275.                                 Case sphere:  ReadDot(spheretex,PickedU()*(TextureWidth(spheretex)-1),PickedV()*(TextureHeight(spheretex)-1))
276.                         End Select
277.                 End If
278.         End If
279.        
280.         ang = (ang + 0.1) Mod 360
281.         TurnEntity cube,-Sin(ang)*0.3,-Cos(ang)*0.3,0
282.         TurnEntity sphere,Sin(ang)*0.1,Cos(ang)*0.1,0
283.        
284.         UpdateWorld
285.         RenderWorld
286.  
287.         ; draw mouse cursor
288.         Line xm-8,ym,xm-4,ym
289.         Line xm+8,ym,xm+4,ym
290.         Line xm,ym-8,xm,ym-4
291.         Line xm,ym+8,xm,ym+4
292.         Oval xm-4,ym-4,9,9,False       
293.  
294.         ; write some info
295.         Text 0,  0,"Use left mousebutton to paint the cube and the sphere"
296.         Text 0, 20,"ent = "+PickedEntity()
297.         Text 0, 35,"surf = "+PickedSurface()
298.         Text 0, 50,"tri = "+PickedTriangle()
299.                        
300.         Text 0, 80,"x = "+PickedX()
301.         Text 0, 95,"y = "+PickedY()
302.         Text 0,110,"z = "+PickedZ()
303.        
304.         Text 0,140,"u = "+PickedU()
305.         Text 0,155,"v = "+PickedV()
306.         Text 0,170,"w = "+PickedW()
307.  
308.         Text 0,200,"nx= "+PickedNX()
309.         Text 0,215,"ny= "+PickedNY()
310.         Text 0,230,"nz= "+PickedNZ()
311.        
312.         Text 14,460,"Use right mousebutton to pick up a texture color"
313.         Color dotred,dotgrn,dotblu
314.         Rect 0,460,12,12,True
315.         Color 255,255,255
316.         Flip
317. Wend
318.  
319. ClearWorld
320. End
321.  
322. ;
323. ; Plots a red dot :)
324. Function PaintRedDot(tex,x,y)
325.         SetBuffer TextureBuffer(tex)
326.        
327.         maxwidth  = TextureWidth(tex)
328.         maxheight = TextureHeight(tex)
329.        
330.         red# = 255
331.         grn# = 0
332.         blu# = 0
333.         WritePixel x,y,blu Or (grn Shl 8) Or (red Shl 16)
334.        
335.         For xx = -1 To 1
336.                 For yy = -1 To 1
337.                         If (xx=0) Xor (yy=0)
338.                                 If (xx<0 And x>0) Or (xx>0 And x<maxwidth) Or (yy<0 And y>0) Or (yy>0 And y<maxheight)
339.                                         argb = ReadPixel(x+xx,y+yy)
340.                                         red# =  64 + (argb Shr 16 And %11111111)
341.                                         grn# =   0 + (argb Shr 8 And %11111111)
342.                                         blu# =   0 + (argb Shr 8 And %11111111)
343.  
344.                                         If red>255 Then red = 255
345.                                         If grn>255 Then grn = 255
346.                                         If blu>255 Then blu = 255
347.                
348.                                         WritePixel x+xx,y+yy,blu Or (grn Shl 8) Or (red Shl 16)
349.                                 End If
350.                         End If
351.                 Next
352.         Next
353.        
354.         SetBuffer BackBuffer()
355. End Function
356.  
357. ;
358. ; Reads a pixel in a texture
359. Function ReadDot(tex,x,y)
360.         SetBuffer TextureBuffer(tex)
361.        
362.         maxwidth  = TextureWidth(tex)
363.         maxheight = TextureHeight(tex)
364.        
365.         If x<maxwidth And y<maxheight
366.                 argb = ReadPixel(x,y)
367.                 dotred# = (argb Shr 16 And %11111111)
368.                 dotgrn# = (argb Shr 8 And %11111111)
369.                 dotblu# = (argb Shr 8 And %11111111)
370.         End If
371.        
372.         SetBuffer BackBuffer()
373. End Function

Comments :


Kryzon(Posted 1+ years ago)

 Looks nice.

[RemiD]

Hello,

I have rewritten the function by our friend Fredborg so that you don't need custom types and the (useless) functions, only one function ( returns PickedU, PickedV )
also i have added a little addon to calculate the picked texel position X,Y ( PickedTX, PickedTY )
with a demo :

Code: [Select]

;PickedU,PickedV by Fredborg
;PickedTX,PickedTY addon by RemiD
;calculates picked U,V with some math wizardry (by Fredborg)
;once the U,V ( PickedU PickedV ) of the picked point is determined, we can calculate the position X,Y of the picked texel ( PickedTX, PickedTY )
Graphics3D(800,600,32,2)

SeedRnd(MilliSecs())

Global PickedU#, PickedV# ;picked U,V
Global PickedTX%, PickedTY% ;picked texel X,Y

Local Cam = CreateCamera()
CameraRange(Cam,0.1,100)
CameraClsColor(Cam,025,025,025)

Local Texture = CreateTexture(64,64,1)
SetBuffer(TextureBuffer(Texture))
ClsColor(250,250,250) : Cls()
;outline of the texture
Color(125,125,125) : Line(0,0,64-1,0)
Color(125,125,125) : Line(0,64-1,64-1,64-1)
Color(125,125,125) : Line(0,0,0,64-1)
Color(125,125,125) : Line(64-1,0,64-1,64-1)
;corner top left (red texel)
Color(255,000,000) : Plot(0,0)
;corner top right (green texel)
Color(000,255,000) : Plot(64-1,0)
;corner bottom left (blue texel)
Color(000,000,255) : Plot(0,64-1)
;corner bottom right (white texel)
Color(255,255,255) : Plot(64-1,64-1)
;some text
Color(025,025,025) : TStr$ = "Fredborg" : TX% = TextureWidth(Texture)/2-StringWidth(TStr)/2 : TY% = TextureHeight(Texture)/2-StringHeight(TStr)/2 : Text(TX,TY,TStr)

Local Mesh = CreateCube()
EntityTexture(Mesh,Texture)
RotateEntity(Mesh,0,Rand(-180,180),0,True)
EntityPickMode(Mesh,2)

PositionEntity(Cam,0,1.65,-3.0)
RotateEntity(Cam,22.5,0,0)

While Not KeyDown(1)

 If( KeyDown(200)=1 )
  TurnEntity(Mesh,+1,0,0)
 Else If( KeyDown(208)=1 )
  TurnEntity(Mesh,-1,0,0)
 EndIf
 If( KeyDown(203)=1 )
  TurnEntity(Mesh,0,-1,0)
 Else If( KeyDown(205)=1 )
  TurnEntity(Mesh,0,+1,0)
 EndIf

 If( MouseDown(1)=1 )
  CameraPick(Cam, MouseX(), MouseY())
  If( PickedEntity() <> 0 And PickedSurface() <> 0 )
   CalculatePickedUVvFredborg() ;by Fredborg
   PickedTX% = TextureWidth(Texture)*PickedU : PickedTY% = TextureHeight(Texture)*PickedV
   DebugLog(PickedU+","+PickedV+"->"+PickedTX+","+PickedTY)
   SetBuffer(TextureBuffer(Texture))
   Color(255,000,255) : Plot(PickedTX,PickedTY)
  EndIf
 EndIf

 SetBuffer(BackBuffer())
 RenderWorld()

 Color(255,255,255)
 Text(0,0,"Mouse Left to pick / color texels on the texture")
 Text(0,16,"Arrows to turn the shape up, down, left, right")

 Flip(True)

Wend

End()

Function CalculatePickedUVvFredborg()

  If( PickedSurface() )

picent = PickedEntity()
picsurf = PickedSurface()
pictri  = PickedTriangle()

picpx# = PickedX()
picpy# = PickedY()
picpz# = PickedZ()

Local picvx#[3], picvy#[3], picvz#[3]
;Local picvnx#[3], picvny#[3], picvnz#[3]
Local picvu#[3], picvv#[3] ; picvw#[3]
Local picpu#[1], picpv#[1] ; picpw#[1]

For i = 0 To 2

TFormPoint(VertexX(picsurf,TriangleVertex(picsurf,pictri,i)),VertexY(picsurf,TriangleVertex(picsurf,pictri,i)),VertexZ(picsurf,TriangleVertex(picsurf,pictri,i)),picent,0)

picvx[i] = TFormedX()
picvy[i] = TFormedY()
picvz[i] = TFormedZ()

;picvnx[i] = VertexNX(picsurf,TriangleVertex(picsurf,pictri,i))
;picvny[i] = VertexNY(picsurf,TriangleVertex(picsurf,pictri,i))
;picvnz[i] = VertexNZ(picsurf,TriangleVertex(picsurf,pictri,i))

picvu[i+0] = VertexU(picsurf,TriangleVertex(picsurf,pictri,i),0)
picvv[i+0] = VertexV(picsurf,TriangleVertex(picsurf,pictri,i),0)
;picvw[i+0] = VertexW(picsurf,TriangleVertex(picsurf,pictri,i),0)

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# = picvx[1] - picvx[0]
a1# = picvy[1] - picvy[0]

; edge 1
b0# = picvx[2] - picvx[0]
b1# = picvy[2] - picvy[0]

; picked offset from triangle vertex 0
c0# = PickedX() - picvx[0]
c1# = PickedY() - picvy[0]
Else
; xz components
If (coords = 2)
; edge 0
a0# = picvx[1] - picvx[0]
a1# = picvz[1] - picvz[0]

; edge 1
b0# = picvx[2] - picvx[0]
b1# = picvz[2] - picvz[0]

; picked offset from triangle vertex 0
c0# = PickedX() - picvx[0]
c1# = PickedZ() - picvz[0]
Else
; yz components

; edge 0
a0# = picvy[1] - picvy[0]
a1# = picvz[1] - picvz[0]

; edge 1
b0# = picvy[2] - picvy[0]
b1# = picvz[2] - picvz[0]

; picked offset from triangle vertex 0
c0# = PickedY() - picvy[0]
c1# = PickedZ() - picvz[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)
picpu[0] = (picvu[0] + ((picvu[1] - picvu[0]) * u) + ((picvu[2] - picvu[0]) * v)) Mod 1
picpv[0] = (picvv[0] + ((picvv[1] - picvv[0]) * u) + ((picvv[2] - picvv[0]) * v)) Mod 1
;picpw[0] = (picvw[0] + ((picvw[1] - picvw[0]) * u) + ((picvw[2] - picvw[0]) * v)) Mod 1

; If any of the coords are negative
If( picpu[0] < 0.0 ) Then picpu[0] = 1.0 + picpu[0]
If( picpv[0] < 0.0 ) Then picpv[0] = 1.0 + picpv[0]
        ;If( picpw[0] < 0.0 ) Then picpw[0] = 1.0 + picpw[0]

PickedU = picpu[0] : PickedV = picpv[0]

End If

End Function
Thanks again Fredborg

[peteswansen]

As usual Remi's coding is really good....so I have been modifying this to load a model in and then "painting" the model in larger blocks of color...nice bit of fun!!

[_PJ_]

What an amazingly useful set of functions!!!
These really belonged in B3D from the start.

Thanks very much RemiD!