====== Texture patterns and look up table ======

===== Pattern: Waves  =====
{{http://hyperfun.org/HF2/Language/Library/Attri_Lib/images/hfA_wave.JPG?200x200&nolink}}\\
**Definition**: t = (1+sin(freq*xt))/2.0 \\
attribute = a0+t*(a1-a0)

**Call**: hfA_Wave(xt,a0,a1,freq);

**Parameters**: \\
xt - point coordinate \\
a0,a1 - Interval in between the returned value belongs \\
freq - Frequency 

**Output** : A value between [a0,a1]

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_Wave.hf|hfA_Wave.hf]]

===== Pattern: CheckerBoard  =====
{{http://hyperfun.org/HF2/Language/Library/Attri_Lib/images/hfA_CheckerBoard.JPG?200x200&nolink}}\\

**Call**: hfA_CheckerBoard(x,bricks,space,s, c_bricks,c_space);

**Parameters**: \\
x - point coordinates array \\
bricks - Size of the bricks. (3D : width,lenght,wide) \\
space - Size of the spaces between the bricks. (3D : width,lenght,wide) \\
s - Output Array \\
c_bricks - array of attributes corresponding to the bricks \\
c_space - array of attributes corresponding to the spaces \\

**Output** : attributes in the s array

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_CheckerBoard.hf|hfA_CheckerBoard.hf]]

===== Pattern: Crackles =====
{{http://hyperfun.org/HF2/Language/Library/Attri_Lib/images/hfA_crackles.JPG?200x200&nolink}}\\

**Definition** : A "noisy" value p is calculated. According to the map array, attributes are applied.

**Call**: hfA_Crackles(x,s,freq, attributes,maps);

**Parameters**: \\
x - point coordinates array \\
s - Output Array. Size k \\
freq - frequency of the pattern \\
attributes - set of array of attributes. Size k(n-1) \\
maps - array of n+2 values :[0,a1,...an,1] \\

**Output** : attributes in the s array

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_Crackles.hf|hfA_Crackles.hf]]

===== Pattern: Concentric Circles (centered around the origin) =====
{{http://hyperfun.org/newFrep/HF/Language/Library/Attri_Lib/images/hfA_circles.JPG?200x200&nolink}}\\

**Definition** : Periodic circular areas are calculated, and attributes are set according to the map array.

**Call**: hfA_Circles(x,s , attributes,maps);

**Parameters**: \\
x - point coordinates array \\
s - Output Array. Size k \\
attributes - set of array of attributes. Size k(n-1) \\
maps - array of n+2 values :[0,a1,...an,1] \\

**Output** : attributes in the s array

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_Circles.hf|hfA_Circles.hf]]

=====  Look up table =====
{{http://hyperfun.org/HF2/Language/Library/Attri_Lib/images/hfA_LookUpTable.JPG?200x200&nolink}}\\

**Definition** : Given a set of intervals (array of n values in [0,1]), and given a set of colors (array of 3*(n-1) values), each set corresponding to an interval, and given a value t in [0,1]. Depending on the interval t belongs to, a set of attributes is set.

**Call**: hfA_LookUpTable(t,s,c,map)

**Parameters**: \\
t - Real value \\
s - Output array (attributes) \\
c - Input array (attributes) \\
map - Input array (interval) \\

**Output** : attributes in the s array

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_LookUpTable.hf|hfA_LookUpTable.hf]]

===== Smooth Look up table =====
{{http://hyperfun.org/newFrep/HF/Language/Library/Attri_Lib/images/hfA_SmoothLookUpTable.JPG?200x200&nolink}}\\

**Definition** : Given a set of intervals (array of n values in [0,1]), and given a set of colors (array of 3*(n-1) values in the case of rgb attributes), each set corresponding to an interval, and given a value t in [0,1]. Depending on the interval t belongs to, a set of attributes is set. A linear interpolation is performed between the set of attributes corresponding to the lower and upper boundary of the interval where t belongs to.

**Call**: hfA_SmoothLookUpTable(t,s,c,map)

**Parameters**: \\
t - Real value \\
s - Output array (attributes) \\
c - Input array (attributes) \\
map - Input array (interval) \\

**Output** : attributes in the s array

**Test file**: [[http://hyperfun.org/HF2/Language/Library/Attri_Lib/hffiles/hfA_SmoothLookUpTable.hf|hfA_SmoothLookUpTable.hf]]