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{
% Starting stack: H, S, V
% /!\ WARNING: The hue component **MUST** be encoded
% in the range [0, 1] before calling this function.
% This is because the function assumes that the
% hue component are divided by a factor of 360
% in order to meet the range requirements of the
% PDF specification.
% First we do H = (H * 360.0) % 360
3 2 roll 360 mul 3 1 roll
% Compute C = V * S
dup 3 1 roll mul
% P = (H / 60) % 2
3 2 roll dup 60 div 2
2 copy div cvi mul exch sub abs
% X = C * (1 - |P - 1|)
1 exch 1 sub abs sub 3 2 roll dup 3 1 roll mul
% Compute m = V - C
exch dup 5 4 roll exch sub
% Rotate so H is top
4 3 roll exch 4 1 roll
% Construct the RGB stack
dup 60 lt {
% We need to build: (C, X, 0)
pop 0 3 1 roll
} {
dup 120 lt {
% We need to build: (X, C, 0)
pop exch 0 3 1 roll
} {
dup 180 lt {
% We need to build: (0, C, X)
pop 0
} {
dup 240 lt {
% We need to build: (0, X, C)
pop exch 0
} {
300 lt {
% We need to build: (X, 0, C)
0 3 2 roll
} {
% We need to build: (C, 0, X)
0 exch
} ifelse
} ifelse
} ifelse
} ifelse
} ifelse
4 3 roll
% Add m to each component
dup dup 6 2 roll add 5 2 roll add exch 4 3 roll add exch
}
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