The RenderMan Interface - Paul Bourke

• conditional execution,
• loops, and
• function calls.
These constructs are all modeled after C. Statement grouping allows a single statement to
be replaced with a sequence of statements.
{
}
stmt;
...
stmt;
Any variables declared within such a brace-delimited series of statements are only visible
within that block. In other words, variables follow the same local scoping rules as in the C
language.
Conditional execution is controlled by
if ( boolean expression ) stmt else stmt
There are two loop statements,
and
while ( boolean expression ) stmt
for ( expr ; boolean expression ; expr ) stmt
A boolean expression is an expression involving a relational operator, one of: , =, ==, and !=. It is not legal to use an arbitrary float, point or color expression directly
as a boolean expression to control execution. A boolean expression can not be used as a
floating point expression.
The
and
break [n]
continue [n]
statements cause either the for or the while loop at level n to be exited or to begin the next
iteration. The default value for n is 1 and refers to the immediately enclosing loop.
Built-in and user-progrmamed functions are called just as in C. The
return expr
statement is used to return a value to the caller. Any functions that do not return a value
should be declared as void, just as in ANSI C, and should not contain a return statement.
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