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AOS VXL Format

File format

Binary, as an array of BYTEs. No endianness issues.

Headerless.

Stores the Collumn data for each of the 2D map squares. Left-to-right, Top-to-bottom;

Example:
First Collumn: (0,0)
511th Collumn: (511,0)
512th Collumn: (0,1)
513th Collumn: (1,1)

Validation Algorythm

  • Check if first 4 bytes are a valid Span Descriptor.

Collumn data

Variable number of Spans.

Consists of repetitions of the Span format.
Last Spanis special : ends with Solid voxels extending down to z=63.

Span data

Variable Runs of voxel data

Encoded using explicit positions (heights) rather then lenghts.

Consists of the folowing Runs of voxels in order unless it's the last Span:

  • 0 or more Open voxels.
  • 1 or more Colored voxels (Top Colored Run).
  • 0 or more Solid voxels.
  • 0 or more Colored voxels (Bottom Colored Run).

Last Span consists of:

  • 1 or more Open voxels.
  • 1 or more Colored voxels (Top Colored Run).
  • All remaining voxels till z=63 are Solid

Stored Top-to-Bottom, (z=0 to z=63).

Heights

Measured starting from z=0 (highest position on sky), to z=63 (lowest position, must always be Solid, behaves as water).

z=62 is Indistructible, lowest non-water ground.

Data definition

START of Header
At byte offset 0, Length of Span data. (N*4 bytes including header) [N]
Note: N=0 defines the last Span of the Collumn
At byte offset 1, Starting height of Top Colored Run [S]
At byte offset 2, Ending height of Top Colored Run [E]
At byte offset 3, Starting height of Air Run [A]
Note: First span ignores value and assumes A=0
END of Header
START of Data
Note: Variable i is defined as 0..(N-1), encoding first colors of Top Colored Run, then encoding colors of Bottom Colored Run
At byte offset (4 + i*4), Blue channel for ith voxel. [b]
At byte offset (5 + i*4), Green channel for ith voxel. [g]
At byte offset (6 + i*4), Red channel for ith voxel. [r]
At byte offset (7 + i*4), Alpha channel for ith voxel. [a]
END of Data

Next byte after the list of colors, located at byte offset (8 + N*4) is the first byte of the next Span.

Useful formulas

Constants:
K is E - S + 1 [Length of Top Colored Run]
Z is (N - 1) - K or 0, If N=0 [Length of Bottom Colored Run]
M is A at Next Span or 64, If N=0

Determining storage space

Span: N
Last Span: 4 * (1 + K)

Open voxel run

Start: A
End: S-1
Length: S-A

Top Colored Run

Start: S
End: E
Length: K

Bottom Colored Run

Start: M - Z
End: M + 1
Length: Z

Solid voxel run

Start: E + 1
End: M - Z - 1
Length: M - Z - (E + 1)

Solid

Surface Voxel Rule

Supply colors for hidden blocks

Map Structure

2D Array of Collumns of voxels.
2D Array is width * height in size; Current format both are 512.

Each Collumn is stored independently of every other Collumn.

Spawning

Spawn locations are implicit on this version of the file format.

  • Blue at (0,128) to (256,384)
  • Red at (384,128) to (512,384)

Voxels

Kinds of voxels:

  • Open (Represent Air)
  • Solid (Represent solid space, are not visible)
  • Colored/Surface (Are visible, and as such must be drawn with a particular color)