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Topic: ray tracer (Read 666 times) |
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bluatigro
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ray tracer
« Thread started on: Feb 26th, 2015, 11:21am » |
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this is a try at a ray tracer
error :
- i got only a black square
Code:
''bluatigro 26 feb 2015
WindowWidth = DisplayWidth
WindowHeight = DisplayHeight
global winx , winy , spmax
winx = WindowWidth
winy = WindowHeight
spmax = 10
dim sp( spmax , 5 )
global spx , spy , spz , spr , spkl , spmat
spx = 0
spy = 1
spz = 2
spr = 3
spkl = 4
spmat = 5
nomainwin
for i = 0 to spmax
call sphere i , range( -100 , 100 ) _
, range( -100 , 100 ) _
, range( 50 , 200 ) _
, range( 10 , 50 ) _
, range( 0 , 2^24-1 ) , 0
next i
open "ray" for graphics as #m
#m "trapclose [quit]"
for x = -100 to 100
for y = -100 to 100
kl = pixel( x,y,0 , x,y,1e10 )
r = kl and 255
g = int( kl / 256 ) and 255
b = int( kl / 256 ^ 2 ) and 255
#m "color " ; rgb$( r , g , b )
#m "goto " ; winx / 2 + x ; " " ; winy / 2 - y
#m "down"
#m "set " ; winy / 2 + x ; " " ; winy / 2 - y
#m "up"
next y
next x
notice "ready !!"
wait
function range( low , high )
range = rnd(0) * ( high - low ) + low
end function
sub sphere no , x,y,z , r , kl , mat
sp( no , spx ) = x
sp( no , spy ) = y
sp( no , spz ) = z
sp( no , spr ) = r
sp( no , spkl ) = kl
sp( no , spmat ) = mat
end sub
function rgb$( r , g , b )
rgb$ = str$( r and 255 ) ; " " ; g and 255 ; " " ; b and 255
end function
function pixel( ox,oy,oz , dx,dy,dz )
minst = 1e10
found = -1
for i = 0 to spmax
d = hit( i , ox,oy,oz , dx,dy,dz )
if d > 0 and d < minst then
minst = d
found = i
end if
next i
if found < 0 then pixel = 0 : exit function
pixel = sp( found , spkl )
end function
function hit( no , ox,oy,oz , dx,dy,dz )
opx = sp( no , spx ) - ox
opy = sp( no , spy ) - oy
opz = sp( no , spz ) - oz
b = dot( opx,opy,opz , dx,dy,dz )
disc = b ^ 2 * dot( opx,opy,opz , dx,dy,dz ) + sp( no , spr ) ^ 2
if disc < 0 then hit = -1 : exit function
disc = sqr( disc )
t = b^2 - disc
if t > 1e-10 then hit = t : exit function
t = b^2 + disc
if t > 1e-10 then hit = t : exit function
hit = -1
end function
function dot( ax,ay,az , bx,by,bz )
dot = ax * bx + ay * by + az * bz
end function
[quit]
close #m
end
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Richard Russell
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Re: ray tracer
« Reply #1 on: Feb 26th, 2015, 12:59pm » |
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on Feb 26th, 2015, 11:21am, bluatigro wrote:| this is a try at a ray tracer |
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Rod Bird did a nice ray tracer some time ago:
Code:nomainwin
'constants to access the point arrays
global X,Y,Z,R,Red,Green,Blue,Xp,Yp,DistToScreen,maxObjects
X=0
Y=1
Z=2
R=3
Red=4
Green=5
Blue=6
'the world is 24x24 units
'0,0 is centre of the world
'-12 far left 12 far right
'12 top -12 bottom
'objects are specified in world units
'rays are specified in world units
'pixel coordinates are converted by
'dividing the world width by the screen width
'and the world height by the screen height
'this gives a per pixel world increment value
ScrXLeft=-12
ScrXRight=12
ScrYTop=-12
ScrYBottom=12
ImgX=512 'pixel width of screen
ImgY=512 'pixel height of screen
ScrX=2*ScrXRight/ImgX 'per pixel world increment value
ScrY=2*ScrYBottom/ImgY
'Calculate how much space windows borders take
'Anatoly's tip
WindowWidth = 200
WindowHeight = 200
open "Ajusting..." for graphics_nsb as #1
#1, "home ; down ; posxy w h"
w=200-2*w : h = 200-2*h
'w and h now contain the number of pixels
'the Windows scheme/theme takes
close #1
WindowWidth = ImgX+w
WindowHeight = ImgY+h
UpperLeftX = int((DisplayWidth-WindowWidth)/2)
UpperLeftY = int((DisplayHeight-WindowHeight)/2)
open "Raytrace" for graphics_nsb as #1
#1 "down ; fill 192 192 192 ; trapclose [quit]"
'sphere data x,y,z,radius,color
'three spheres ,red green and blue
'evenly spaced around centre of screen
'z order front to back blue, green, red
'there are five massive spheres positioned
'all round the edges and to the rear to create walls
maxObjects=7
dim sp(maxObjects,6)
sp(0,X)=0
sp(0,Y)=0
sp(0,Z)=5
sp(0,R)=4
sp(0,Red)=255
sp(0,Green)=0
sp(0,Blue)=0
sp(1,X)=-6
sp(1,Y)=0
sp(1,Z)=5
sp(1,R)=2
sp(1,Red)=0
sp(1,Green)=255
sp(1,Blue)=0
sp(2,X)=6
sp(2,Y)=0
sp(2,Z)=2
sp(2,R)=2
sp(2,Red)=0
sp(2,Green)=0
sp(2,Blue)=255
sp(3,X)=-36
sp(3,Y)=0
sp(3,Z)=20
sp(3,R)=26
sp(3,Red)=64
sp(3,Green)=128
sp(3,Blue)=255
sp(4,X)=36
sp(4,Y)=0
sp(4,Z)=20
sp(4,R)=26
sp(4,Red)=64
sp(4,Green)=128
sp(4,Blue)=255
sp(5,X)=0
sp(5,Y)=-36
sp(5,Z)=20
sp(5,R)=26
sp(5,Red)=64
sp(5,Green)=128
sp(5,Blue)=25
sp(6,X)=0
sp(6,Y)=36
sp(6,Z)=20
sp(6,R)=26
sp(6,Red)=64
sp(6,Green)=128
sp(6,Blue)=25
sp(7,X)=0
sp(7,Y)=0
sp(7,Z)=36
sp(7,R)=24
sp(7,Red)=128
sp(7,Green)=128
sp(7,Blue)=128
'point origin of camera
'centre screen, 24 world units back from the image plane
cam(X)=0
cam(Y)=0
cam(Z)=-24
'point origin of light source
'centre top, on the image plane
lit(X)=12
lit(Y)=5
lit(Z)=-10
'now cast a ray through every pixel on the screen
for Xp=0 to ImgX
for Yp=0 to ImgY
scan
'point0, the camera x,y,z
o(X)=cam(X) 'world x camera 0
o(Y)=cam(Y) 'world y camera 0
o(Z)=cam(Z) 'world z camera -10
'point1, the screen x,y,z
'which is ScrXLeft (-12) + .5 * ScrX, the per pixel world increment value
'to which we add xp * ScrX to give world x in world units
r(X)=ScrXLeft+.5*ScrX+Xp*ScrX 'world x
r(Y)=ScrYTop+.5*ScrY+Yp*ScrY 'world y
r(Z)=0 'world z image plane 0
'flat parrallell ray no perspective
'o(X)=r(X)
'o(Y)=r(Y)
'o(Z)=-10
'subtract point0 from point1 to get vector direction d()
d(X)=r(X)-o(X)
d(Y)=r(Y)-o(Y)
d(Z)=r(Z)-o(Z)
'normalize it by dividing by its length to make a unit vector ie it sums to 1
l=sqr(d(X)*d(X)+d(Y)*d(Y)+d(Z)*d(Z))
d(X)=d(X)/l
d(Y)=d(Y)/l
d(Z)=d(Z)/l
DistToScreen=l
'go look for an intersect
null=raySphereIntersect()
next 'y
next 'x
wait
[quit]
close #1
end
function raySphereIntersect()
maxdist=1000000
for o=0 to maxObjects
b=2*d(X)*(o(X)-sp(o,X))+2*d(Y)*(o(Y)-sp(o,Y))+2*d(Z)*(o(Z)-sp(o,Z))
c=(o(X)-sp(o,X))^2+(o(Y)-sp(o,Y))^2+(o(Z)-sp(o,Z))^2-sp(o,R)^2
d = b * b - 4 * c
if d>0 then
t=(b*-1 - sqr(b*b-4*c))/2
if t>DistToScreen then
'store the shortest intersect of all sphere intersects
if t<maxdist then maxdist=t : id=o
end if
end if
next
if maxdist<1000000 then
'establish the sphere surface intersect point
i(X)=o(X)+d(X)*maxdist
i(Y)=o(Y)+d(Y)*maxdist
i(Z)=o(Z)+d(Z)*maxdist
'get unit normal vector from sphere centre to surface intersect
n(X)=(i(X)-sp(id,X))/sp(id,R)
n(Y)=(i(Y)-sp(id,Y))/sp(id,R)
n(Z)=(i(Z)-sp(id,Z))/sp(id,R)
'get the unit normal vector from sphere surface intersect to the light
l(X)=lit(X)-i(X)
l(Y)=lit(Y)-i(Y)
l(Z)=lit(Z)-i(Z)
l=sqr(l(X)*l(X)+l(Y)*l(Y)+l(Z)*l(Z))
l(X)=l(X)/l
l(Y)=l(Y)/l
l(Z)=l(Z)/l
'the dot product of these vectors gives an indication of the light
color=n(X)*l(X)+n(Y)*l(Y)+n(Z)*l(Z)
'cast a ray from intersect to the light to check for shadow
'we have done most of the ray prep
'point0 is the intersect point1 is the light
'so l() is our ray direction, point1-point0, normalized
shadow=1
for o=0 to maxObjects
if o<>id then 'check all other spheres not the one we are currently considering
b=2*l(X)*(i(X)-sp(o,X))+2*l(Y)*(i(Y)-sp(o,Y))+2*l(Z)*(i(Z)-sp(o,Z))
c=(i(X)-sp(o,X))^2+(i(Y)-sp(o,Y))^2+(i(Z)-sp(o,Z))^2-sp(o,R)^2
d = b * b - 4 * c
if d>0 then t=(b*-1 - sqr(b*b-4*c))/2
if d>0 and t>0 then shadow=.5 : exit for
end if
next
'add some ambient light
if color < .3 then color = .3
'color the pixel
#1 "color ";sp(id,Red)*color*shadow;" ";sp(id,Green)*color*shadow;" ";sp(id,Blue)*color*shadow;" ; set ";Xp;" ";Yp
end if
end function
Richard.
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bluatigro
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Re: ray tracer
« Reply #3 on: Mar 1st, 2015, 10:12am » |
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@richard :
- i m trying to rebild the code example you gave
i got this far Code:
nomainwin
'constants to access the point arrays
global X,Y,Z,R,clr,Xp,Yp,DistToScreen,maxObjects
X=0
Y=1
Z=2
R=3
clr=4
global sptel
'the world is 24x24 units
'0,0 is centre of the world
'-12 far left 12 far right
'12 top -12 bottom
'objects are specified in world units
'rays are specified in world units
'pixel coordinates are converted by
'dividing the world width by the screen width
'and the world height by the screen height
'this gives a per pixel world increment value
ScrXLeft=-12
ScrXRight=12
ScrYTop=-12
ScrYBottom=12
ImgX=512 'pixel width of screen
ImgY=512 'pixel height of screen
ScrX=2*ScrXRight/ImgX 'per pixel world increment value
ScrY=2*ScrYBottom/ImgY
'Calculate how much space windows borders take
'Anatoly's tip
WindowWidth = 200
WindowHeight = 200
open "Ajusting..." for graphics_nsb as #1
#1, "home ; down ; posxy w h"
w=200-2*w : h = 200-2*h
'w and h now contain the number of pixels
'the Windows scheme/theme takes
close #1
WindowWidth = ImgX+w
WindowHeight = ImgY+h
UpperLeftX = int((DisplayWidth-WindowWidth)/2)
UpperLeftY = int((DisplayHeight-WindowHeight)/2)
open "Raytrace" for graphics_nsb as #1
#1 "down ; fill 192 192 192 ; trapclose [quit]"
'sphere data x,y,z,radius,color
'three spheres ,red green and blue
'evenly spaced around centre of screen
'z order front to back blue, green, red
'there are five massive spheres positioned
'all round the edges and to the rear to create walls
maxObjects=7
dim sp(maxObjects,4)
call sphere 0,0,5 , 4 , rgb(255,0,0)
call sphere 0,5,2 , 2 , rgb(0,255,0)
call sphere 6,0,2 , 2 , rgb(0,0,255)
call sphere -1e5-12,20,26 , 1e5 , rgb(64,128,255)
call sphere 1e5+12,20,26 , 1e5 , rgb(64,128,255)
call sphere 0,-1e5-12,26 , 1e5 , rgb(64,128,255)
call sphere 0,1e5+12,26 , 1e5 , rgb(64,128,255)
call sphere 0,0,1e5+12 , 1e5 , rgb(128,128,128)
'point origin of camera
'centre screen, 24 world units back from the image plane
cam(X)=0
cam(Y)=0
cam(Z)=-24
'point origin of light source
'centre top, on the image plane
lit(X)=12
lit(Y)=5
lit(Z)=-10
'now cast a ray through every pixel on the screen
for Xp=0 to ImgX
for Yp=0 to ImgY
scan
'point0, the camera x,y,z
o(X)=cam(X) 'world x camera 0
o(Y)=cam(Y) 'world y camera 0
o(Z)=cam(Z) 'world z camera -10
'point1, the screen x,y,z
'which is ScrXLeft (-12) + .5 * ScrX, the per pixel world increment value
'to which we add xp * ScrX to give world x in world units
r(X)=ScrXLeft+.5*ScrX+Xp*ScrX 'world x
r(Y)=ScrYTop+.5*ScrY+Yp*ScrY 'world y
r(Z)=0 'world z image plane 0
'flat parrallell ray no perspective
'o(X)=r(X)
'o(Y)=r(Y)
'o(Z)=-10
'subtract point0 from point1 to get vector direction d()
d(X)=r(X)-o(X)
d(Y)=r(Y)-o(Y)
d(Z)=r(Z)-o(Z)
'normalize it by dividing by its length to make a unit vector ie it sums to 1
l=sqr(d(X)*d(X)+d(Y)*d(Y)+d(Z)*d(Z))
d(X)=d(X)/l
d(Y)=d(Y)/l
d(Z)=d(Z)/l
DistToScreen=l
'go look for an intersect
null=raySphereIntersect()
next 'y
next 'x
wait
[quit]
close #1
end
function rgb( a , b , c )
rgb = a + b * 256 + c * 256 ^ 2
end if
function clr.r( kl )
clr.r = kl and 255
end function
function clr.g( kl )
clr.g = int( kl / 256 ) and 255
end function
function clr.b( kl )
clr.b = int( kl / 256 ^ 2 ) and 255
end function
sub sphere a , b , c , d , kl
if sptel > maxObjects then exit sub
sp( sptel , X ) = a
sp( sptel , Y ) = b
sp( sptel , Z ) = c
sp( sptel , R ) = d
sp( sptel , clr ) = kl
sptel = sptel + 1
end sub
function raySphereIntersect()
maxdist=1000000
for o=0 to maxObjects
b=2*d(X)*(o(X)-sp(o,X))+2*d(Y)*(o(Y)-sp(o,Y))+2*d(Z)*(o(Z)-sp(o,Z))
c=(o(X)-sp(o,X))^2+(o(Y)-sp(o,Y))^2+(o(Z)-sp(o,Z))^2-sp(o,R)^2
d = b * b - 4 * c
if d>0 then
t=(b*-1 - sqr(b*b-4*c))/2
if t>DistToScreen then
'store the shortest intersect of all sphere intersects
if t<maxdist then maxdist=t : id=o
end if
end if
next
if maxdist < 1e7 then
'establish the sphere surface intersect point
i(X)=o(X)+d(X)*maxdist
i(Y)=o(Y)+d(Y)*maxdist
i(Z)=o(Z)+d(Z)*maxdist
'get unit normal vector from sphere centre to surface intersect
n(X)=(i(X)-sp(id,X))/sp(id,R)
n(Y)=(i(Y)-sp(id,Y))/sp(id,R)
n(Z)=(i(Z)-sp(id,Z))/sp(id,R)
'get the unit normal vector from sphere surface intersect to the light
l(X)=lit(X)-i(X)
l(Y)=lit(Y)-i(Y)
l(Z)=lit(Z)-i(Z)
l=sqr(l(X)*l(X)+l(Y)*l(Y)+l(Z)*l(Z))
l(X)=l(X)/l
l(Y)=l(Y)/l
l(Z)=l(Z)/l
'the dot product of these vectors gives an indication of the light
color=n(X)*l(X)+n(Y)*l(Y)+n(Z)*l(Z)
'cast a ray from intersect to the light to check for shadow
'we have done most of the ray prep
'point0 is the intersect point1 is the light
'so l() is our ray direction, point1-point0, normalized
shadow=1
for o=0 to maxObjects
if o<>id then 'check all other spheres not the one we are currently considering
b=2*l(X)*(i(X)-sp(o,X))+2*l(Y)*(i(Y)-sp(o,Y))+2*l(Z)*(i(Z)-sp(o,Z))
c=(i(X)-sp(o,X))^2+(i(Y)-sp(o,Y))^2+(i(Z)-sp(o,Z))^2-sp(o,R)^2
d = b * b - 4 * c
if d>0 then t=(b*-1 - sqr(b*b-4*c))/2
if d>0 and t>0 then shadow=.5 : exit for
end if
next
'add some ambient light
if color < .3 then color = .3
kl = sp( id , clr )
'color the pixel
#1 "color " ; clr.r( kl ) * color * shadow _
;" " ; clr.g( kl ) * color * shadow _
;" " ; clr.b( kl ) * color * shadow
#1 "set " ; Xp ; " " ; Yp
end if
end function
error :
- 'no shuts fn/proc at line 61
lbb recognises rgb() function not
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Richard Russell
Administrator
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Posts: 1348
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Re: ray tracer
« Reply #4 on: Mar 1st, 2015, 11:23am » |
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on Mar 1st, 2015, 10:12am, bluatigro wrote:| i m trying to rebild the code example you gave |
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Why? Rod's code works without any modification. Just copy-and-paste it from the forum into LBB.
Quote:| no shuts fn/proc at line 61 |
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END IF -> END FUNCTION !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
Richard.
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bluatigro
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Posts: 111
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Re: ray tracer
« Reply #5 on: Mar 1st, 2015, 1:02pm » |
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Quote:Why? Rod's code works without any modification. Just copy-and-paste it from the forum into LBB.
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@richard :
- i want to create animations whit this
- and i want to make the code clearer
- in the future i want to use more OOP like code
- now only spheres exsit i want more shapes
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| « Last Edit: Mar 2nd, 2015, 11:56am by bluatigro » |
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bluatigro
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Posts: 111
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Re: ray tracer
« Reply #6 on: Mar 2nd, 2015, 11:53am » |
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update :
- more functions
error :
- black screen
Code:
''bluatigro 1 mrt 2015
''rebild of internet raytracer
nomainwin
'constants to access the point arrays
global X,Y,Z,R,clr,Xp,Yp,DistToScreen,maxObjects
X = 0
Y = 1
Z = 2
R = 3
clr = 4
global sptel
'the world is 24x24 units
'0,0 is centre of the world
'-12 far left 12 far right
'12 top -12 bottom
'objects are specified in world units
'rays are specified in world units
'pixel coordinates are converted by
'dividing the world width by the screen width
'and the world height by the screen height
'this gives a per pixel world increment value
global ScrXleft , ScrXRight , ScrYTop , ScrYBottom
ScrXLeft=-12
ScrXRight=12
ScrYTop=-12
ScrYBottom=12
global ImgX , ImgY , ScrX , Scry
ImgX=512 'pixel width of screen
ImgY=512 'pixel height of screen
ScrX=2*ScrXRight/ImgX 'per pixel world increment value
ScrY=2*ScrYBottom/ImgY
'Calculate how much space windows borders take
'Anatoly's tip
WindowWidth = 200
WindowHeight = 200
open "Ajusting..." for graphics_nsb as #1
#1, "home ; down ; posxy w h"
w=200-2*w : h = 200-2*h
'w and h now contain the number of pixels
'the Windows scheme/theme takes
close #1
WindowWidth = ImgX+w
WindowHeight = ImgY+h
UpperLeftX = int((DisplayWidth-WindowWidth)/2)
UpperLeftY = int((DisplayHeight-WindowHeight)/2)
open "Raytrace" for graphics_nsb as #1
#1 "down ; fill black ; trapclose [quit]"
global red , green , blue , gray
red = rgb( 255 , 0 , 0 )
green = rgb( 0 , 255 , 0 )
blue = rgb( 0 , 0 , 255 )
gray = rgb( 200 , 200 , 200 )
'sphere data x,y,z,radius,color
'three spheres ,red green and blue
'evenly spaced around centre of screen
'z order front to back blue, green, red
'there are five massive spheres positioned
'all round the edges and to the rear to create walls
maxObjects = 10
dim sp( maxObjects , 4 )
call sphere 0,0,5 , 4 , red
call sphere 0,5,2 , 2 , green
call sphere 6,0,2 , 2 , blue
call sphere -1e5-12,20,26 , 1e5 , gray
call sphere 1e5+12,20,26 , 1e5 , gray
call sphere 0,-1e5-12,26 , 1e5 , gray
call sphere 0,1e5+12,26 , 1e5 , gray
call sphere 0,0,1e5+12 , 1e5 , gray
'point origin of camera
'centre screen, 24 world units back from the image plane
cam(X) = 0
cam(Y) = 0
cam(Z) = -24
'point origin of light source
'centre top, on the image plane
lit(X) = -11
lit(Y) = -11
lit(Z) = -11
call render
notice "ready !!"
wait
sub render
'now cast a ray through every pixel on the screen
for Xp=0 to ImgX
for Yp=0 to ImgY
scan
'point0, the camera x,y,z
o(X) = cam(X) 'world x camera 0
o(Y) = cam(Y) 'world y camera 0
o(Z) = cam(Z) 'world z camera -10
'point1, the screen x,y,z
'which is ScrXLeft (-12) + .5 * ScrX, the per pixel world increment value
'to which we add xp * ScrX to give world x in world units
r(X) = ScrXLeft + 0.5 * ScrX + Xp * ScrX 'world x
r(Y) = ScrYTop + 0.5 * ScrY + Yp * ScrY 'world y
r(Z) = 0 'world z image plane 0
'flat parrallell ray no perspective
'o(X)=r(X)
'o(Y)=r(Y)
'o(Z)=-10
'subtract point0 from point1 to get vector direction d()
d(X) = r(X) - o(X)
d(Y) = r(Y) - o(Y)
d(Z) = r(Z) - o(Z)
'normalize it by dividing by its length to make a unit vector ie it sums to 1
l = sqr( d(X) * d(X) + d(Y) * d(Y) + d(Z) * d(Z) )
d(X) = d(X) / l
d(Y) = d(Y) / l
d(Z) = d(Z) / l
DistToScreen = l
'go look for an intersect
null = raySphereIntersect()
next 'y
next 'x
end sub
[quit]
close #1
end
function nr$( no , digits )
nr$ = right$( "0000000000" ; no , digits )
end function
sub savescreen a$
#1 "getbmp screen 0 0 " ; ImgX ; " " ; ImgY
bmpsave "screen" , a$ + ".bmp"
end sub
function rgb( a , b , c )
rgb = a + b * 256 + c * 256 ^ 2
end function
function clr.r( kl )
clr.r = kl and 255
end function
function clr.g( kl )
clr.g = int( kl / 256 ) and 255
end function
function clr.b( kl )
clr.b = int( kl / 256 ^ 2 ) and 255
end function
sub sphere a , b , c , d , kl
if sptel >= maxObjects then exit sub
sp( sptel , X ) = a
sp( sptel , Y ) = b
sp( sptel , Z ) = c
sp( sptel , R ) = d
sp( sptel , clr ) = kl
sptel = sptel + 1
end sub
function Sphere.dist( o )
uit = 1e7
b = 2 * d(X) * ( o(X) - sp(o,X)) _
+ 2 * d(Y) * ( o(Y) - sp(o,Y)) _
+ 2 * d(Z) * ( o(Z) - sp(o,Z))
c = ( o(X) - sp(o,X) ) ^ 2 _
+ ( o(Y) - sp(o,Y) ) ^ 2 _
+ ( o(Z) - sp(o,Z) ) ^ 2 - sp(o,R) ^ 2
d = b * b - 4 * c
if d > 0 then
uit = ( b * -1 - sqr( b * b - 4 * c ) ) / 2
end if
Sphere.dist = uit
end function
function raySphereIntersect()
maxdist = 1e7
for o = 0 to sptel
t = Sphere.dist( o )
if t > DistToScreen then
'store the shortest intersect of all sphere intersects
if t < maxdist then maxdist = t : id = o
end if
next
if maxdist < 1e7 then
'establish the sphere surface intersect point
i(X) = o(X) + d(X) * maxdist
i(Y) = o(Y) + d(Y) * maxdist
i(Z) = o(Z) + d(Z) * maxdist
'get unit normal vector from sphere centre to surface intersect
n(X) = ( i(X) - sp(id,X) ) / sp(id,R)
n(Y) = ( i(Y) - sp(id,Y) ) / sp(id,R)
n(Z) = ( i(Z) - sp(id,Z) ) / sp(id,R)
'get the unit normal vector from sphere surface intersect to the light
l(X) = lit(X) - i(X)
l(Y) = lit(Y) - i(Y)
l(Z) = lit(Z) - i(Z)
l = sqr( l(X) * l(X) + l(Y) * l(Y) + l(Z) * l(Z) )
l(X) = l(X) / l
l(Y) = l(Y) / l
l(Z) = l(Z) / l
'the dot product of these vectors gives an indication of the light
color = n(X) * l(X) + n(Y) * l(Y) + n(Z) * l(Z)
'cast a ray from intersect to the light to check for shadow
'we have done most of the ray prep
'point0 is the intersect point1 is the light
'so l() is our ray direction, point1-point0, normalized
shadow = 1
o(X) = i(X)
o(Y) = i(Y)
o(Z) = i(Z)
d(X) = l(X)
d(Y) = l(Y)
d(Z) = l(Z)
for o = 0 to sptel
if o <> id then
'check a ll other spheres not the one we are currently considering
t = Sphere.dist( o )
if t > 0 and t < 1e7 then shadow = 0.5 : exit function
end if
next
'add some ambient light
if color < .3 then color = .3
kl = sp( id , clr )
'color the pixel
#1 "color " ; clr.r( kl ) * color * shadow _
; " " ; clr.g( kl ) * color * shadow _
; " " ; clr.b( kl ) * color * shadow
#1 "set " ; Xp ; " " ; Yp
else
#1 "color black"
#1 "set " ; Xp ; " " ; Yp
end if
end function
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Richard Russell
Administrator
member is offline
Posts: 1348
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Re: ray tracer
« Reply #7 on: Mar 2nd, 2015, 1:32pm » |
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on Mar 2nd, 2015, 11:53am, bluatigro wrote:
LBB v3.00 (released yesterday) has a 'File... Compare' feature which shows the differences between a program and an earlier version. You may find it helpful to compare your non-working version with Rod's original; one (or more) of the changes must be the reason for the failure.
Richard.
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