mirror of https://git.minetest.land/MineClone2/MineClone2.git synced 2024-12-04 16:53:46 +01:00

teknomunk b582afeb1f Update documentation for Minetest rename to Luanti (#4706 )

This updates the VoxeLibre documentation by replacing "Minetest" with "Luanti" and updating links.

Done:
* Update "Minetest" in documentation and comments to "Luanti"
* Update links to forums, ContentDB and Luanti project web page

Reviewed-on: https://git.minetest.land/VoxeLibre/VoxeLibre/pulls/4706
Reviewed-by: the-real-herowl <the-real-herowl@noreply.git.minetest.land>
Co-authored-by: teknomunk <teknomunk@protonmail.com>
Co-committed-by: teknomunk <teknomunk@protonmail.com>

2024-11-28 20:55:48 +01:00

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tga_encoder

A TGA Encoder written in Lua without the use of external Libraries.

Created by fleckenstein for VoxeLibre, then improved by erlehmann.

May be used as a Luanti mod.

See examples.lua for example code and usage hints.

Use Cases for `tga_encoder`

Encoding Textures for Editing

TGA images of types 1/2/3 consist of header data followed by a pixel array.

This makes it trivial to parse TGA files – and even edit pixels in-place.

No checksums need to be updated on any kind of in-place texture editing.

Tip: When storing an editable image in item meta, use zlib compression.

Legacy Luanti Texture Encoding

Luanti 5.4 did not include minetest.encode_png() (or any equvivalent).

Since tga_encoder is written in pure Lua, it does not need engine support.

Tip: Look at examples.lua and the Luanti mod mcl_maps for guidance.

Advanced Texture Format Control

The function minetest.encode_png() always encodes images as 32bpp RGBA.

tga_encoder allows saving images as grayscale, 16bpp RGBA and 24bpp RGB.

For generating maps from terrain, color-mapped formats can be more useful.

Encoding Very Small Textures

Images of size 8×8 or below are often smaller than an equivalent PNG file.

Note that on many filesystems files use at least 4096 bytes (i.e. 64×64).

Therefore, saving bytes on files up to a few 100 bytes is often useless.

Encoding Reference Textures

TGA is a simple format, which makes it easy to create reference textures.

Using a hex editor, one can trivially see how all the pixels are stored.

Supported Image Types

For all types, images are encoded in a fast single pass (i.e. append-only).

Color-Mapped Images (Type 1)

These images contain a palette, followed by pixel data.

A1R5G5B5 (8bpp RGB)
B8G8R8 (8bpp RGB)
B8G8R8A8 (8bpp RGBA)

True-Color Images (Type 2)

These images contain uncompressed RGB(A) pixel data.

A1R5G5B5 (16bpp RGBA)
B8G8R8 (24bpp RGB)
B8G8R8A8 (32bpp RGBA)

Grayscale Images (Type 3)

Y8 (8bpp grayscale)

Run-Length Encoded (RLE), True-Color Images (Type 10)

These images contain compressed RGB(A) pixel data.

A1R5G5B5 (16bpp RGBA)
B8G8R8 (24bpp RGB)
B8G8R8A8 (32bpp RGBA)

TODO

Actually support R8G8B8A8 input for A1R5G5B5 output
Add both zoomable and explorable maps to mcl_maps.

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