Within a trigger, actions will normally be carried out one after another in sequence. Sometimes we might want to repeat things, or do things only under certain conditions. Slow Glass provides several means of doing this but they are deliberately kept quite simple.

Conditional Execution

if {condition}

endif

This is quite straight forward, it the condition looks like something that is “true” (see the section on expressions for full details) then the lines between if and endif are excuted. If the condition is false they are not.

Note that the lines beween these commands can only be other commands (not triggers or directives), but it can include other if conditions, you can next them to any depth that you like.

At the moment there is no else clause, you can just test the “other” version of the condition in a separate statement.

For Loops

for {var-name} in {values...}

for {var-name} range {N..M}

endfor / next

This command will run the actions between the for and *endfor lines several times, each time the named variable will take a new value. In the first form the values are a list of space separated words (but you can combine words by putting them within quotation marks).

In the second version the values will run from N to M where both are integers and M is larger than N.

For loops can also be nested to any required depth but be sure to use different variable names for each loop.

Repeat loops

If you just want to do something a number of times or until a particular you can use these commands.

repeat

until {condition}

while {condition}

This will run the actions between repeat and until / while and then evaluate the condtion. With until the actions will be repeated until the condition becomes true (i.e. as long as the condition is false); with while it will repeat as long as the condition is true.

Repeat loops can be nested as many times as you like.

Calling a Routine

A set of actions, sometimes referred as a routine can be invoked by using the following action:

call {routine-name} {arguments...}

Elsewhere in the scene there should be a set of actions headed by an on call cue, with the same name. This action causes processing of the current set of actions to be suspended and those of the called routine actioned, until all are complete.

Any arguments passed to the called routine are available in the built-in variable $ARGS / $ARGUMENTS.

Called routines can be nested to any depth but be careful not to make recursive calls, these are not not prevented and will cause the program to crash.

Call routines provide another mechanism to repeat a set of actions, but rather than repeating a fixed number of times they can be used from various points in the script.

Combining Flow Control

As noted above, flow control commands cen be nested to any depth. They can also be combined in any way that you need, however recall that one of the design goals of Slow Glass is simplicity, so very complex, deeply nested code is probably not helpful!