layer_get_script_begin

You supply the layer ID (which you get when you create the layer using layer_create()) or the layer name (as a string - this will have a performance impact) and this function will return the script function index of the function assigned to run at the beginning of rendering for that layer, or it will return -1 if no function is assigned. You can assign script functions to a layer with layer_script_begin() and layer_script_end().

Syntax:

layer_get_script_begin(layer_id);

Returns:

Script Function Index (Real) or -1 if no script is assigned

Example:

if layer_get_script_begin(layer) == -1
   {
   layer_script_begin(layer, scr_SetShaderValues);
   }

The above code will check to see if the layer that the instance running the code has a script function assigned to it and if it doesn't one is assigned.