Difference between revisions of "III/VC SCM"

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{{Cleanup-rewrite}}
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  (02 00 01)h + 32-bit offset    '''GOTO''' next header chunk
== Overall Format ==
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  byte                           Target game ('l' - Liberty for III, 'm' - Miami for VC, unused at runtime)
  (02 00 01)h + 32-bit int    Jump to second segment
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  32-bit int                  Number of cutscene starts (VC Mobile only, unused at runtime)
  byte                         Target game ('l' - Liberty for III, 'm' - Miami for VC)
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  (Cutscene start array)      32-bit offset of '''START_CUTSCENE''' command * 300 (VC Mobile only, unused at runtime)
   (Global vars)             Space for variable saving
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   (Global variable space)     Space for global variable storage (first global offset is 8, 1212 in VC Mobile)
  (02 00 01)h + 32-bit int    Jump to third segment
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  (02 00 01)h + 32-bit offset    '''GOTO''' next header chunk
  byte                         Padding (always 0)
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  byte                           Alignment (always 0, ignored)
   32-bit int                 Number of models
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   32-bit int                   Number of used objects (always 1 in VC Mobile{{ref|*}})
   (Model names)             24-byte model names * number of models (model 0 name is empty and therefore unused)
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   (Used object array)         24-byte object name * number of used objects (first object name is empty and therefore unused)
  (02 00 01)h + 32-bit int    Jump to fourth segment
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  (02 00 01)h + 32-bit offset    '''GOTO''' main script space (third header chunk is compiled only in script multifile)
  byte                         Padding (always 0)
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  byte                           Alignment (always 0, ignored)
   32-bit int                 MAIN size
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   32-bit int                   Main script size
   32-bit int                 Largest mission size
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   32-bit int                   Largest mission script size
   16-bit int                 Number of total missions
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   16-bit int                   Number of mission scripts (120 in total)
   16-bit int                 Number of exclusive missions
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   16-bit int                   Number of exclusive mission scripts (possibly 1 in III, 2 in VC)
   (Mission addresses)       32-bit addresses * number of missions
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   (Multi script array)         32-bit offset * number of mission scripts
  (MAIN code)                 MAIN section, equal to size defined earlier
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  (Main script space)           Space of main script (equal to size defined earlier)
  (Mission code)               The mission data, missions stored at offsets defined earlier
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  (Mission scripts space)       Space of mission scripts (each one is stored at file offsets defined earlier)
  
== Main Section ==
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{{note|*}} Compiler-wise, the model names of level objects are picked directly from [[OBJS]] and [[TOBJ]] sections of the [[IDE]] files whose <code>IDE Filename</code> begins with <code>DATA\</code> in [[Gta.dat|gta_vc.dat]].
Made up of many opcodes one after the other. Opcodes are of the format:
 
<source lang="c">TOpcode {
 
  Opcode[2]: Word; //Opocode number in word format
 
  Parameters: Array Of TParameter;
 
}</source>
 
The number of parameters is specific for each opcode. The [http://vc-db.webtools4you.net/ opcode database] has all of the opcodes in VC, with their parameter numbers, and for most, a description of what they do.
 
Parameters are of the format:
 
<source lang="c">TParameter {
 
  ParameterType[1]: Byte; //Says which type of parameter will follow
 
  ActualParameter: varies; //The actual parameter
 
}</source>
 
The [[Mission Scripting (Overview)#Data types|parameter types]] are as follows (but there are more in SA):
 
01: 32-bit int  (DWord)
 
02: global var  (Word)
 
03: local var    (Word)
 
04: 8-bit int    (Byte)
 
05: 16-bit int  (Word)
 
06: 4-byte float (Single)
 
[[Label]]s use the type 01 (although if they address is small enough using data types 04 and 05 will also work). Global and local vars can also be used for labels.
 
Global vars reference a position in the file much like a label. There is a space at the top of the scm file filled with 00's which is space reserved for global vars. This is divided into blocks of 4 bytes, each var taking up one of these blocks. In compiled form, the global vars each point to somewhere in that block (or should do as otherwise writing to it will modify the actual code).
 
== Example ==
 
This code:
 
<source lang="scm">0001: wait 8 ms
 
0002: jump $var1
 
0050: gosub 1@
 
0051: return</source>
 
 
...compiles as:
 
01 00 04 08 //wait opcode (First 2 bytes = opcode, next byte = 04 the parameter type for 8-bit int, and 08 is the actual value)
 
02 00 02 18 00 // jump opcode. The 18 00 would mean that the global var is stored at address 0x0018
 
50 00 03 01 00 //the gosub opcode
 
51 00 //the return opcode (it has no parameters)
 
 
 
{{Script-stub}}
 
  
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{{N|VC|III}}
 
[[Category:Mission Script]] [[Category:File Formats]]
 
[[Category:Mission Script]] [[Category:File Formats]]

Latest revision as of 23:25, 12 January 2021

(02 00 01)h + 32-bit offset    GOTO next header chunk
byte                           Target game ('l' - Liberty for III, 'm' - Miami for VC, unused at runtime)
  32-bit int                   Number of cutscene starts (VC Mobile only, unused at runtime)
  (Cutscene start array)       32-bit offset of START_CUTSCENE command * 300 (VC Mobile only, unused at runtime)
  (Global variable space)      Space for global variable storage (first global offset is 8, 1212 in VC Mobile)
(02 00 01)h + 32-bit offset    GOTO next header chunk
byte                           Alignment (always 0, ignored)
  32-bit int                   Number of used objects (always 1 in VC Mobile[*])
  (Used object array)          24-byte object name * number of used objects (first object name is empty and therefore unused)
(02 00 01)h + 32-bit offset    GOTO main script space (third header chunk is compiled only in script multifile)
byte                           Alignment (always 0, ignored)
  32-bit int                   Main script size
  32-bit int                   Largest mission script size
  16-bit int                   Number of mission scripts (120 in total)
  16-bit int                   Number of exclusive mission scripts (possibly 1 in III, 2 in VC)
  (Multi script array)         32-bit offset * number of mission scripts
(Main script space)            Space of main script (equal to size defined earlier)
(Mission scripts space)        Space of mission scripts (each one is stored at file offsets defined earlier)

^ Compiler-wise, the model names of level objects are picked directly from OBJS and TOBJ sections of the IDE files whose IDE Filename begins with DATA\ in gta_vc.dat.