Installation

Installation

Requirements

Component	Version used	Needed for
MSYS2 mingw-w64-x86_64 GCC, C++20	15.x	everything
CMake	>= 3.16	build
Ninja	any	build
mingw-w64-x86_64-openjpeg2	2.5.4	JPEG 2000 decoding
mingw-w64-x86_64-libpng	1.6.58	PNG output
mingw-w64-x86_64-gtest	1.17.0	unit tests
mingw-w64-x86_64-qt6-base	6.x	optional, GUI only

pacman -S --needed mingw-w64-x86_64-{toolchain,cmake,ninja,openjpeg2,libpng,gtest,qt6-base}

Linux (Debian / Ubuntu)

The same project builds against the distribution packages. Verified on Ubuntu 24.04 / Linux Mint 22 with GCC 13, CMake 3.28 and Ninja.

Component	Package	Needed for
GCC / C++20, CMake >= 3.16, Ninja	g++, cmake, ninja-build	everything
OpenJPEG 2.5	libopenjp2-7-dev	JPEG 2000 decoding
libpng 1.6	libpng-dev	PNG output
GoogleTest	libgtest-dev	unit tests
Qt 6 Widgets	qt6-base-dev	optional, GUI only

sudo apt-get install -y g++ cmake ninja-build libopenjp2-7-dev libpng-dev libgtest-dev qt6-base-dev

Qt 6 is optional: without it the GUI target is skipped and the build stays green. -DSLTCD_BUILD_GUI=OFF turns it off explicitly.

Build

Windows (MSYS2)

Run these from an MSYS2 MINGW64 shell (or any shell that has C:\msys64\mingw64\bin on PATH; the compiler, CMake and Ninja are all needed):

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=C:/msys64/mingw64
cmake --build build
ctest --test-dir build --output-on-failure

-DCMAKE_PREFIX_PATH=C:/msys64/mingw64 is what lets find_package locate Qt 6, OpenJPEG and libpng; it is harmless if Qt 6 is not installed.

Linux (Debian / Ubuntu)

The distribution packages are found without a prefix path:

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build --output-on-failure

libopenjp2-7-dev installs OpenJPEGConfig.cmake without a matching OpenJPEGConfigVersion.cmake, so the versioned find_package(OpenJPEG 2.5) is reported as "version: unknown" and rejected. CMakeLists.txt handles this by trying the versioned form first and falling back to the unversioned one when no version file is present.

For a development build use -DCMAKE_BUILD_TYPE=Debug (the test suite is quick, ~3 s, and does not need a real cache: tests/data/ holds a frozen slice).

Products

The binaries carry a .exe suffix in a Windows build and no suffix on Linux.

File	What it is
build/bin/SLTextureDecoder.exe	the command line tool
build/bin/SLTextureDecoderGUI.exe	the Qt 6 front end and the --batch headless mode
build/bin/sl_texture_decoder_tests.exe	the gtest binary
build/lib/libsl_texture_decoder_core.a	the decoding library the front ends link against

Deploying the GUI

Qt 6 from MSYS2 is linked dynamically. Either put C:\msys64\mingw64\bin on PATH, or copy the runtime next to the executable:

windeployqt --release build/bin/SLTextureDecoderGUI.exe

The CLI and the core library need only libopenjp2-7.dll, libpng16-16.dll and the GCC runtime, which windeployqt also brings along.

Where the viewer keeps its cache

The tool needs the directory that contains texture.entries, texture.cache and the 0..f shard folders. Typical Windows locations:

Viewer	Directory
Second Life (official viewer), 64 bit	%APPDATA%\SecondLife_x64\texturecache
Second Life (official viewer), 32 bit	%APPDATA%\SecondLife\texturecache
Firestorm Viewer	%APPDATA%\Firestorm_x64\texturecache
Firestorm (older 32 bit builds)	%APPDATA%\Firestorm\texturecache

Rules of thumb:

• %APPDATA% is C:\Users\<you>\AppData\Roaming; the directory name follows the viewer's own cache name, so a third party viewer may use a different one.
• If the viewer was installed into a custom location or you use several accounts, search for texture.entries and take the folder that also contains texture.cache and the hex named subdirectories.
• Open the cache while the viewer is closed, or at least accept that the viewer may rewrite/trim the cache while the tool reads it. The tool opens the cache read-only and never modifies it.

Then point the tool at it (see Usage):

.\build\bin\SLTextureDecoder.exe --cache-dir "$env:APPDATA\Firestorm_x64\texturecache" --limit 5 -v

Uninstall / cleanup

Nothing is installed system wide. Delete build/ and the output directory, and

• if you want to forget the GUI settings as well - the registry key HKCU\Software\SLTextureDecoder\GUI.