# `vk-bootstrap`

A utility library that jump starts initialization of Vulkan 

This library simplifies the tedious process of:

* Instance creation
* Physical Device selection
* Device creation
* Getting queues
* Swapchain creation

It also adds several conveniences for:

* Enabling validation layers
* Adding a debug callback messenger
* Enabling extensions on a physical device
* Select a gpu based on a set of criteria like features, extensions, memory, etc

Read the [Getting Started](docs/getting_started.md) guide for a quick start on using `vk-bootstrap`

## Basic Usage

```cpp

#include "VkBootstrap.h"

bool init_vulkan () {
    vkb::InstanceBuilder builder;
    auto inst_ret = builder.set_app_name ("Example Vulkan Application")
                        .request_validation_layers ()
                        .use_default_debug_messenger ()
                        .build ();
    if (!inst_ret) {
        std::cerr << "Failed to create Vulkan instance. Error: " << inst_ret.error().message() << "\n";
        return false;
    }
    vkb::Instance vkb_inst = inst_ret.value ();

    vkb::PhysicalDeviceSelector selector{ vkb_inst };
    auto phys_ret = selector.set_surface (/* from user created window*/)
                        .set_minimum_version (1, 1) // require a vulkan 1.1 capable device
                        .require_dedicated_transfer_queue ()
                        .select ();
    if (!phys_ret) {
        std::cerr << "Failed to select Vulkan Physical Device. Error: " << phys_ret.error().message() << "\n";
        return false;
    }

    vkb::DeviceBuilder device_builder{ phys_ret.value () };
    // automatically propagate needed data from instance & physical device
    auto dev_ret = device_builder.build ();
    if (!dev_ret) {
        std::cerr << "Failed to create Vulkan device. Error: " << dev_ret.error().message() << "\n";
        return false;
    }
    vkb::Device vkb_device = dev_ret.value ();

    // Get the VkDevice handle used in the rest of a vulkan application
    VkDevice device = vkb_device.device;

    // Get the graphics queue with a helper function
    auto graphics_queue_ret = vkb_device.get_queue (vkb::QueueType::graphics);
    if (!graphics_queue_ret) {
        std::cerr << "Failed to get graphics queue. Error: " << graphics_queue_ret.error().message() << "\n";
        return false;
    }
    VkQueue graphics_queue = graphics_queue_ret.value ();

    // Turned 400-500 lines of boilerplate into less than fifty.
    return true;
}
```

See `example/triangle.cpp` for an example that renders a triangle to the screen.

## Setting up `vk-bootstrap`

This library has no external dependencies beyond C++14, its standard library, and the Vulkan Headers.

Note: on Unix platforms, `vk-bootstrap` will require the dynamic linker in order to compile as the library doesn't link against `vulkan-1.dll`/`libvulkan.so` directly. 

### Copy-Paste

Copy the `src/VkBootstrap.h` and `src/VkBootstrap.cpp` files into your project, include them into your build, then compile as you normally would.

`vk-bootstrap` is *not* a header only library, so no need to worry about macros in the header.

### git-submodule + CMake

Add this project as a git-submodule into the root directory. Suggested is using a subdirectory to hold all submodules.

```bash
git submodule add https://github.com/charles-lunarg/vk-bootstrap
```

With CMake, add the subdirectory to include the project

```cmake
add_subdirectory(vk-bootstrap)
```

Then use `target_link_libraries` to use the library in whichever target needs it. 

```cmake
target_link_libraries(your_application_name vk-bootstrap)
```

### CMake Fetch Content
If cmake 3.12 is available, use the FetchContent capability of cmake to directly download and build the library for you.

```cmake
include(FetchContent)
FetchContent_Declare(
    fetch_vk_bootstrap
    GIT_REPOSITORY https://github.com/charles-lunarg/vk-bootstrap
    GIT_TAG        BRANCH_OR_TAG #suggest using a tag so the library doesn't update whenever new commits are pushed to a branch 
)
FetchContent_MakeAvailable(fetch_vk_bootstrap)
target_link_libraries(your_application_name vk-bootstrap)
```

### Manually Building

```bash
git clone https://github.com/charles-lunarg/vk-bootstrap
cd vk-bootstrap
mkdir build
cd build
cmake ..
```

### Vulkan-Headers dependency

By default, when using vk-bootstrap through CMake, it will attempt to locate the Vulkan-Headers on the system and fall back to downloading them directly if they aren't present. If the `VK_BOOTSTRAP_VULKAN_HEADER_DIR` option is specified, it will use that directory instead.


### Testing

Tests will be enabled if you open this project standalone. If you include this project as a subdirectory or sub-project, you can force enable tests by setting the option `VK_BOOTSTRAP_TEST` to `ON`. Testing requires GLFW and Catch2 but are acquired automatically using cmake fetch content.

```bash
cmake ../path/to/your_project/ -DVK_BOOTSTRAP_TEST=ON
```

### Build Options
| Name | Type |  Default Value | Description |
| ---- | --- | ---- | ----- | 
| `VK_BOOTSTRAP_TEST` | bool | `OFF` | Enable building of the tests in this project. Will download GLFW and Catch2 automatically if enabled. |
| `VK_BOOTSTRAP_VULKAN_HEADER_DIR` | string | `""` | Optional. Specify the directory that contains the Vulkan Headers. Useful if you are downloading the headers manually and don't want vk-bootstrap to download them itself. |