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This file contains some quick notes about this plugin.
======================================================
Some useful links:
------------------
<http://codeincomplete.com/projects/racer/> - a very good tutorial on building a similar game in Javascript
<http://www.extentofthejam.com/pseudo/> - excellent page on pseudo-3d
Terminology:
------------
In the code, a "fixed-point" number is one that has a nonzero number of fractional bits.
When dealing with these numbers, you must be careful to convert all operands to fixed-point, and use the correct function/macro to replace the operators.
In the code, I've tried to make all fixed-point numbers of type 'long.'
An "integer" is a number with zero fractional bits.
(NOTE: I'm not sure if this "proper" terminology)
Code structure:
---------------
generator.c: random map generator
graphics.c: this is where almost all of the rendering takes place
main.c: main loop
sprite.c: static sprite data (offsets, dimensions)
util.c miscellaneous functions, also contains FOV calculation code
Proposed map formats:
---------------------
There will be two map formats: one that can be compiled into the executable ("Internal format"), and one that can be loaded from a file ("Interchange format").
Internal format:
----------------
This format is represented as a series of struct road_section's.
struct road_section {
uchar type;
uint32 len;
int slope;
long curve; // <<< this is fixed-point with 8 fracbits
};
'type' can be any of the following:
0: constant segment - all 3 parameters used
1: up-hill - an up hill is added. actual length is len + 2*slope due to enters and exits
2: down-hill - a down hill is added. actual length is len + 2*slope due to enters and exits
Endianness is platform-dependent in the Internal format.
Interchange format:
-------------------
NOTE: all numbers are BIG-ENDIAN unless otherwise specified!
This format is essentially the Internal format serialized into a file, but with some minor differences.
File extension: .xrm
Current format version number: 0x0000
- File header - 8 bytes
- 0x00-0x04: 'XMaP'
- 0x05-0x06: version number (see above)
- 0x07-0x08: 0xFF padding
- Data blocks - 15 bytes each (corresponds to the "sections" of the Internal format)
- 0x00 : type
- 0x01-0x04: length
- 0x05-0x08: slope (signed two's complement)
- 0x09-0x0C: curve (signed two's complement, fixed-point with 8 fractional bits)
- 0x0D-0x0E: CRC16-CCITT of data from 0x0-0xC
- 0x0F : CRC high byte XOR CRC low byte
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