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Perlin noise: Difference between revisions

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Perlin noise (view source)

Revision as of 00:47, 19 November 2019

216 bytes added ,  4 years ago
m
→‎{{header|REXX}}: added whitespace, changed some comments, elided quotation marks for a long constant.
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m (→‎{{header|REXX}}: added whitespace, changed some comments, elided quotation marks for a long constant.)
Line 1,185:
The original decimal (data) table was compressed into a single hexadecimal value (without spaces).
<lang rexx>/*REXX program implements a Perlin noise algorithm of a point in 3D─space. */
_=' 97a0895b5a0f830dc95f6035c2e907e18c24671e458e086325f0150a17be0694f778ea4b001ac53e5efcdbcb75230b2039b12158ed953857ae147d88aba844af',
||'4aa547868b301ba64d929ee7536fe57a3cd385e6dc695c29372ef528f4668f3641193fa101d85049d14c84bbd05912a9c8c4878274bc9f56a4646dc6adba0340',
||'34d9e2fa7c7b05ca2693767eff5255d4cfce3be32f103a11b6bd1c2adfb7aad577f898022c9aa346dd99659ba72bac09811627fd13626c6e4f71e0e8b2b97068',
||'daf661e4fb22f2c1eed2900cbfb3a2f1513391ebf90eef6b31c0d61fb5c76a9db854ccb07379322d7f0496fe8aeccd5dde72431d1848f38d80c34e42d73d9cb4'
do j=0 for length(_)%2; @.j= x2d( substr(_, 2 * j + 1, 2)); end /*assign indexed array.*/)
end /*j*/ /* [↑] assign an indexed array. */
parse arg x y z d . /*obtain optional arguments from the CL*/
if x=='' | x=="," then x= 3.14 /*Not specified? Then use the default.*/
if y=='' | y=="," then y= 42 42 /* " " " " " " */
if z=='' | z=="," then z= 7 7 /* " " " " " " */
if d=='' | d=="," then d=100 100 /* " " " " " " */
numeric digits d /*use D decimal digits for precision.*/
say 'Perlin noise for the 3D point ['space(x y z, 3)"] ───► " PerlinNoise(x, y, z)
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
fade: procedure; parse arg t; return t**3 * (t * (t * 6 - 15) + 10)
floor: procedure; parse arg x; _= x % 1; return _ - (x < 0) * (x \= _)
lerp: procedure; parse arg t,a,b; return a + t * (b - a)
pick: _= abs( arg(1) ) // 256; return @._
/*──────────────────────────────────────────────────────────────────────────────────────*/
grad: procedure; parse arg hash,x,y,z; _= abs(hash) // 16 /*force positive remainder.*/
select
when _== 0 | _==12 then return x+y; when _== 1 | _==14 then return y-x
when _== 2 then return x-y; when _== 3 then return -x-y
when _== 4 then return x+z; when _== 5 then return z-x
when _== 6 then return x-z; when _== 7 then return -x-z
when _== 8 then return y+z; when _== 9 | _==13 then return z-y
when _==10 then return y-z
otherwise otherwise return -y-z /*for cases 11 or 15. */
end /*select*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
PerlinNoise: procedure expose @.; parse arg x,y,z
x$= floor(x) // 256; x = x - floor(x); xm= x-1; u= fade(x)
y$= floor(y) // 256; y = y - floor(y); ym= y-1; v= fade(y)
z$= floor(z) // 256; z = z - floor(z); zm= z-1; w= fade(z)
a = pick(x$ ) + y$; aa= pick(a) + z$; ab= pick(a +1) + z$
b = pick(x$ +1) + y$; ba= pick(b) + z$; bb= pick(b +1) + z$
Line 1,229 ⟶ 1,230:
lerp(u, grad( pick(ab+1), x , ym, zm ), ,
grad( pick(bb+1), xm, ym, zm )))) /1</lang>
'''{{out|output''' |text=&nbsp; when using the internal default inputs:}}
 
(Output note: &nbsp; this REXX program uses '''100''' decimal digit precision, but ''20'' decimal digits would've been adequate.)
 
(Note that REXX uses &nbsp; ''decimal'' &nbsp; floating point, &nbsp; not binary.)
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