// This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License.
// To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a
// letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.

// Persistence of Vision Ray Tracer version 3.8 Include File. (Customized for povr fork)
// File: forkversionhook.inc
// Last updated: 07 February 2022

// Description: Provides a means to determine the fork string name and
// fork version for unofficial POV-Ray forks/branches/patches.

// It uses the f_odd() inbuilt function which has since its addition been a
// useless duplicate of f_cushion(). Where the f_odd() function has been
// modified to return 99.0 no matter the four numeric arguments, it indicates
// paired parse functions named fork_str(n) and fork_val(n) are available.

// At a minimum these be useable for querying the fork name (fork_str(0))and
// version (fork_val(0)). It may be additional indexes with more information
// are provided.

// If there were a time machine available, we'd drop back 20 years and add the
// two fork_* parse time functions to the official POV-Ray code. Then
// patch/fork/branch creators would have access to such functions without
// reverting to the f_odd()=99 back door, hook. However, we are where we are.

// For povr one can set the global variable 'Dump_povr_fork_' to anything.  to
// quickly test if running a povr fork of POV-Ray and the information available
// for the fork_* function pairs. This include file can be run alone with
// commands such as:

// povr +mv3.8 +iforkversionhook.inc declare=Dump_povr_fork_=1
//
// povray +iforkversionhook.inc

//------------------------------------------------------------------------------

#ifndef (Forkversionhook_include_temp)

#declare Forkversionhook_include_temp = version;

#version 3.5;  //  Enable official POV-Ray back to v3.5 to run this.

#ifdef (View_POV_Include_Stack)
    #debug "including forkversionhook.inc\n"
#end

#macro Have_f_odd_fork_hook()
    #local Func_ = function {internal(43)}; // This f_odd() index.
    ((99 = Func_(0.99,0.99,0.99,99)) & (99 = Func_(0,0,0,0)))
#end

// Elsewhere define or uncomment line below to dump available "povr" fork_str
// and fork_val pairs to debug output with a stop using #error before render.
// #declare Dump_povr_fork_ = true;

#if ((Have_f_odd_fork_hook()) & (defined(Dump_povr_fork_)))
    #if (!strcmp(fork_str(0),"povr"))
        #debug "\n-------- Available fork_str, fork_val indexes and information --------\n"
        #debug concat("\nfork_str(0) = ",fork_str(0))
        #debug concat("\nfork_val(0) = ",str(fork_val(0),6,4)," and it's the povr fork version.\n")

        #debug concat("\nfork_str(1) = ",fork_str(1))
        #debug concat("\nfork_val(1) = ",str(fork_val(1),6,4),"\n")

        #local ForkStr = fork_str(2); // Done like this to test assignments.
        #local ForkVal = fork_val(2);

        #debug concat("\nfork_str(2) = ",ForkStr)
        #debug concat("\nfork_val(2) = ",str(ForkVal,6,4),"\n")
        #debug "----------------------------------------------------------------------\n"

        #error "\n\nStop after wrting povr's available fork_str() and fork_val() pairs.\n"
    #else
        #error "\n\nDid not find fork_str(0) to be the string 'povr'.\nNo fork_str() and fork_val() output generated.\n"
    #end
#else

#end

#version Forkversionhook_include_temp;

#end

// Example code using only Have_f_odd_fork_hook() after including this file.
// Place code below in a file name testHook.pov or similar an uncomment.
// Run via <cmd> testHook.pov.
//---
//#version 3.7;
//
//global_settings {assumed_gamma 1}
//box {0,1}
//
//#include "forkversionhook.inc"
//
//#if (Have_f_odd_fork_hook())
//    #debug "\nFound f_odd hook indicating fork_str(), fork_var() parse functions exist.\n\n"
//#else
//    #debug "\nNo f_odd hook indicating fork_str(), fork_var() parse functions exist.\n\n"
//#end
//
//#error "\nStopping early.\nThis example code using forkversionhook.inc and Have_f_odd_fork_hook() macro.\n"
//