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Add DEFAULT_ADDITIONAL_DIRS CMake option
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The main motivation behind this change is to make it easier to package
Descent 3 for Linux. For example, let’s say that you’re packaging
Descent 3 for Debian and you want to make the package work well with
Debian’s game-data-packager. The package for the Descent 3 engine will
put d3-linux.hog in one directory, and the package for the proprietary
Descent 3 game data will put d3.hog into a different directory [1]. The
Descent 3 engine package can use the DEFAULT_ADDITIONAL_DIRS CMake
option in order to make sure that both d3-linux.hog and d3.hog are
located automatically.

For the example value in USAGE.md, I decided to use Windows paths in
order to showcase the fact that you have to escape backslashes.

[1]: <#373 (comment)>
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@Jayman2000
Jayman2000 committed Jan 3, 2025
1 parent d143d08 commit a2dc357
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23 changes: 12 additions & 11 deletions BUILD.md
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Expand Up @@ -179,14 +179,15 @@ cmake --preset linux -DENABLE_LOGGER=ON

**NOTE:** CMake variables, or more technically _CMake cache entries_, will persist in their values until they are explicitly cleared. So, if you set a variable and then run another CMake command _without_ that variable specified, the variable will still be set. Variables must be explicitly unset, or the `builds/` directory cleaned, in order to be cleared.

| Option | Description | Default |
|--------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------|
| `CMAKE_BUILD_TYPE` | `Debug` builds are generally larger, slower and contain extra correctness checks that will validate game data and interrupt gameplay when problems are detected.<br>`Release` builds are optimized for size and speed and do not include debugging information, which makes it harder to find problems. | `Debug` |
| `BUILD_EDITOR` | _(Windows-only)_ Build internal editor. | `OFF` |
| `BUILD_TESTING` | Enable testing. Requires GTest. | `OFF` |
| `ENABLE_LOGGER` | Enable logging to the terminal. | `OFF` |
| `ENABLE_MEM_RTL` | Enable Real-time library memory management functions (disable to verbose memory allocations). | `ON` |
| `FORCE_COLORED_OUTPUT` | Always produce ANSI-colored compiler warnings/errors (GCC/Clang only; esp. useful with Ninja). | `OFF` |
| `FORCE_PORTABLE_INSTALL` | Install all files into local directory defined by `CMAKE_INSTALL_PREFIX`. | `ON` |
| `USE_EXTERNAL_PLOG` | Use system plog library. | `OFF` |
| `USE_VCPKG` | Explicitly control whether or not to use vcpkg for dependency resolution. `ON` requires the environment variable `VCPKG_ROOT` to be set. | Determined by the existence of `VCPKG_ROOT` in the environment: If it exists, vcpkg is used. |
| Option | Description | Default |
|---------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------|
| `CMAKE_BUILD_TYPE` | `Debug` builds are generally larger, slower and contain extra correctness checks that will validate game data and interrupt gameplay when problems are detected.<br>`Release` builds are optimized for size and speed and do not include debugging information, which makes it harder to find problems. | `Debug` |
| `BUILD_EDITOR` | _(Windows-only)_ Build internal editor. | `OFF` |
| `BUILD_TESTING` | Enable testing. Requires GTest. | `OFF` |
| `DEFAULT_ADDITIONAL_DIRS` | A list of directories that Descent 3 will use as read-only base directories (see [USAGE.md’s Base directories section](./USAGE.md#base-directories)). This value gets interpreted as a C++ expression, so you’ll need to use C++’s syntax. Here’s an example of a valid value: <pre lang=cpp>`{"C:\\Games\\Descent3\\", "D:\\"}`</pre> | `{}` |
| `ENABLE_LOGGER` | Enable logging to the terminal. | `OFF` |
| `ENABLE_MEM_RTL` | Enable Real-time library memory management functions (disable to verbose memory allocations). | `ON` |
| `FORCE_COLORED_OUTPUT` | Always produce ANSI-colored compiler warnings/errors (GCC/Clang only; esp. useful with Ninja). | `OFF` |
| `FORCE_PORTABLE_INSTALL` | Install all files into local directory defined by `CMAKE_INSTALL_PREFIX`. | `ON` |
| `USE_EXTERNAL_PLOG` | Use system plog library. | `OFF` |
| `USE_VCPKG` | Explicitly control whether or not to use vcpkg for dependency resolution. `ON` requires the environment variable `VCPKG_ROOT` to be set. | Determined by the existence of `VCPKG_ROOT` in the environment: If it exists, vcpkg is used. |
3 changes: 3 additions & 0 deletions Descent3/init.cpp
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Expand Up @@ -1414,6 +1414,9 @@ void InitIOSystems(bool editor) {
ddio_SetWorkingDir(writable_base_directory.u8string().c_str());
cf_AddBaseDirectory(writable_base_directory);

// Set the default base directories
cf_AddDefaultBaseDirectories();

// Set any additional base directories
auto additionaldirarg = 0;
while (0 != (additionaldirarg = FindArg("-additionaldir", additionaldirarg))) {
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8 changes: 5 additions & 3 deletions USAGE.md
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Expand Up @@ -92,18 +92,19 @@ Descent 3 has two types of base directories:
- The writable base directory can contain both read-write files and read-only files. There is only one writeable base directory. By default, the writable base directory gets set to the current working directory.
- The read-only base directories can only contain read-only files. There can be any number of read-only base directories. By default, Descent 3 uses zero read-only base directories.

You can set the writable base directory and the list of read-only base directories using the `-setdir`, `-useexedir` and `-additionaldir` command-line options (see [the next section](#command-line-options)).
You can set the writable base directory and the list of read-only base directories using the `-setdir`, `-useexedir` and `-additionaldir` command-line options (see [the next section](#command-line-options)). Descent 3 also has a list of default read-only base directories. Normally, the list of default read-only base directories is empty, but you can change it by using the `DEFAULT_ADDITIONAL_DIRS` CMake option when compiling Descent 3 (see [BUILD.md’s Build Options section](./BUILD.md#build-options)).

When Descent 3 tries to find a read-only file, then it will look through the list of base directories in this order:

- the last read-only base directory that was specified on the command-line,
- the second-to-last read-only base directory that was specified on the command-line,
- the third-to-last read-only base directory that was specified on the command-line,
- …
- the first read-only base directory that was specified on the command-line and, finally,
- the first read-only base directory that was specified on the command-line,
- all of the items on the `DEFAULT_ADDITIONAL_DIRS` list in reverse order, and, finally,
- the writable base directory.

Files that are in base directories that are higher on that list will override files that are in base directories that are lower on that list. For example, lets say that you run Descent 3 like this:
Files that are in base directories that are higher on that list will override files that are in base directories that are lower on that list. For example, lets say that the `DEFAULT_ADDITIONAL_DIRS` list is empty and that you run Descent 3 like this:

```
Descent3 -setdir /home/user/my-writable-base-directory -additionaldir /home/user/my-read-only-base-directory
Expand Down Expand Up @@ -527,6 +528,7 @@ The following command-line options are available in Descent 3. You can set comma

**Description:** Tells Descent 3 to use the directory in which the executable is located as the writable base directory.


### Other Options

- `-logfile`
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11 changes: 10 additions & 1 deletion cfile/CMakeLists.txt
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@@ -1,5 +1,6 @@
set(HEADERS
cfile.h
default_base_directories.h
hogfile.h
inffile.h)
set(CPPS
Expand All @@ -8,7 +9,15 @@ set(CPPS
inffile.cpp
)

add_library(cfile STATIC ${HEADERS} ${CPPS})
set(DEFAULT_ADDITIONAL_DIRS "{}" CACHE STRING "A list of directories that Descent 3 will use as read-only base directories.")
set(DBD_CPP ${CMAKE_CURRENT_BINARY_DIR}/default_base_directories.cpp)
configure_file(
${CMAKE_CURRENT_SOURCE_DIR}/default_base_directories.cpp.in
${DBD_CPP}
@ONLY
)

add_library(cfile STATIC ${HEADERS} ${CPPS} ${DBD_CPP})
target_link_libraries(cfile PRIVATE
ddebug
ddio
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12 changes: 12 additions & 0 deletions cfile/cfile.cpp
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Expand Up @@ -30,6 +30,7 @@
#include "byteswap.h"
#include "crossplat.h"
#include "cfile.h"
#include "default_base_directories.h"
#include "ddio.h"
#include "hogfile.h" //info about library file
#include "log.h"
Expand Down Expand Up @@ -78,6 +79,17 @@ cfile_error cfe;
// The message for unexpected end of file
const char *eof_error = "Unexpected end of file";

/* The user can specify a list of default read-only base directories by setting
* the -DDEFAULT_ADDITIONAL_DIRS CMake option. This function adds those base
* directories to the list of base directories that the game is currently
* using.
*/
void cf_AddDefaultBaseDirectories() {
for (const auto &base_directory : Default_read_only_base_directories) {
cf_AddBaseDirectory(base_directory);
}
}

/* This function should be called at least once before you use anything else
* from this module.
*/
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7 changes: 7 additions & 0 deletions cfile/cfile.h
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Expand Up @@ -155,6 +155,13 @@ extern std::vector<std::filesystem::path> Base_directories;
*/
void cf_AddBaseDirectory(const std::filesystem::path &base_directory);

/* The user can specify a list of default read-only base directories by setting
* the -DDEFAULT_ADDITIONAL_DIRS CMake option. This function adds those base
* directories to the list of base directories that the game is currently
* using.
*/
void cf_AddDefaultBaseDirectories();

/* After you call this function, you must call cf_AddBaseDirectory() at least
* once before you use anything else from this module.
*/
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23 changes: 23 additions & 0 deletions cfile/default_base_directories.cpp.in
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@@ -0,0 +1,23 @@
/*
* Descent 3
* Copyright (C) 2024 Descent Developers
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <filesystem>
#include <initializer_list>

#include "default_base_directories.h"

const std::initializer_list<std::filesystem::path> Default_read_only_base_directories = @DEFAULT_ADDITIONAL_DIRS@;
26 changes: 26 additions & 0 deletions cfile/default_base_directories.h
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@@ -0,0 +1,26 @@
/*
* Descent 3
* Copyright (C) 2024 Descent Developers
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef DEFAULT_ADDITIONAL_DIRECTORIES_H
#define DEFAULT_ADDITIONAL_DIRECTORIES_H

#include <filesystem>
#include <initializer_list>

extern const std::initializer_list<std::filesystem::path> Default_read_only_base_directories;

#endif

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