2.8.3.4 User defined Functions

User-Defined Functions

USER_FUNCTION:

FLOAT_USER_FUNCTION | VECTOR_USER_FUNCTION | COLOR_USER_FUNCTION

FLOAT_USER_FUNCTION:

function { FN_FLOAT } | function (IDENT_LIST) { FN_FLOAT } | function { pattern { PATTERN [PATTERN_MODIFIERS]} }

IDENT_LIST:

IDENT_ITEM [, IDENT_LIST]

The maximum number of parameter identifiers is 56. An identifier may not be repeated in the list.

IDENT_ITEM:

x | y | z | u | v | PARAM_IDENTIFIER

PATTERN:

MAP_PATTERN | brick [BRICK_ITEM] | checker | hexagon | object { LIST_OBJECT }

VECTOR_USER_FUNCTION:

function { SPECIAL_VECTOR_FUNCTION }

SPECIAL_VECTOR_FUNCTION:

TRANSFORM | SPLINE

COLOR_USER_FUNCTION:

function { PIGMENT }

Specify a float expression in a user-defined function:

FN_FLOAT

LOGIC_AND [OR LOGIC_AND]

OR:

|

LOGIC_AND:

REL_TERM [AND REL_TERM]

AND:

&

REL_TERM:

TERM [REL_OPERATOR TERM]

REL_OPERATOR:

< | <= | = | >= | > | !=

TERM:

FACTOR [SIGN FACTOR]

SIGN:

+ | -

FACTOR:

EXPRESSION [MULT EXPRESSION]

MULT:

* | /

EXPRESSION:

FLOAT_LITERAL | FLOAT_IDENTIFIER | FN_FLOAT_FUNCTION | FLOAT_BUILT_IN_IDENT | ( FN_FLOAT ) | IDENT_ITEM | SIGN EXPRESSION | VECTOR_FUNCTION_INVOCATION.FN_DOT_ITEM | COLOR_FUNCTION_INVOCATION.FN_DOT_ITEM | FLOAT_FUNCTION_INVOCATION

FN_DOT_ITEM:

DOT_ITEM | hf

FN_FLOAT_FUNCTION:

abs (FN_FLOAT) | acos (FN_FLOAT) | acosh (FN_FLOAT) | asin (FN_FLOAT) | asinh (FN_FLOAT) | atan (FN_FLOAT) | atanh (FN_FLOAT) | atan2 (FN_FLOAT,FN_FLOAT) | ceil (FN_FLOAT) | cos (FN_FLOAT) | cosh (FN_FLOAT) | degrees (FN_FLOAT) | exp (FN_FLOAT) | floor (FN_FLOAT) | int (FN_FLOAT) | ln (FN_FLOAT) | log (FN_FLOAT) | max (FN_FLOAT,FN_FLOAT[,FN_FLOAT]...) | min (FN_FLOAT,FN_FLOAT[,FN_FLOAT]...) | mod (FN_FLOAT,FN_FLOAT) | pow (FN_FLOAT,FN_FLOAT) | prod (IDENTIFIER, FN_FLOAT, FN_FLOAT, FN_FLOAT) | radians (FN_FLOAT) | sin (FN_FLOAT) | sinh (FN_FLOAT) | sqrt (FN_FLOAT) | sum (IDENTIFIER, FN_FLOAT, FN_FLOAT, FN_FLOAT) |tan (FN_FLOAT) | tanh (FN_FLOAT) | select (FN_FLOAT,FN_FLOAT,FN_FLOAT [,FN_FLOAT])

Create an identifier for a user-defined function:

USER_FUNCTION_DECLARATION:

#declare FLOAT_FUNCTION_IDENTIFIER = FLOAT_USER_FUNCTION |
#local FLOAT_FUNCTION_IDENTIFIER = FLOAT_USER_FUNCTION |
#declare VECTOR_FUNCTION_IDENTIFIER = VECTOR_USER_FUNCTION |
#local VECTOR_FUNCTION_IDENTIFIER = VECTOR_USER_FUNCTION |
#declare COLOR_FUNCTION_IDENTIFIER = COLOR_USER_FUNCTION |
#local COLOR_FUNCTION_IDENTIFIER = COLOR_USER_FUNCTION

Reference a user-defined function:

FLOAT_FUNCTION_INVOCATION:

FLOAT_FUNCTION_IDENTIFIER (FN_PARAM_LIST)

VECTOR_FUNCTION_INVOCATION:

VECTOR_FUNCTION_IDENTIFIER (FN_PARAM_LIST)

COLOR_FUNCTION_INVOCATION:

COLOR_FUNCTION_IDENTIFIER (FN_PARAM_LIST)

FN_PARAM_LIST:

FN_PARAM_ITEM [, FN_PARAM_LIST]

FN_PARAM_ITEM:

x | y | z | u | v | FLOAT

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