284 lines
12 KiB
Markdown
284 lines
12 KiB
Markdown
Ash
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A very lightweight wrapper around Vulkan
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-
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[](https://crates.io/crates/ash)
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[](https://docs.rs/ash)
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[](https://github.com/MaikKlein/ash/actions?workflow=CI)
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[](LICENSE-MIT)
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[](LICENSE-APACHE)
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[](https://gitter.im/MaikKlein/ash?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
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## Overview
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- [x] A true Vulkan API without compromises
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- [x] Convenience features without limiting functionality
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- [x] Additional type safety
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- [x] Device local function pointer loading
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- [x] No validation, everything is **unsafe**
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- [x] Generated from `vk.xml`
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- [x] Support for Vulkan `1.1`, `1.2`
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## Features
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### Explicit returns with `Result`
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```rust
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// function signature
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pub fn create_instance(&self,
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create_info: &vk::InstanceCreateInfo,
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allocation_callbacks: Option<&vk::AllocationCallbacks>)
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-> Result<Instance, InstanceError> { .. }
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let instance = entry.create_instance(&create_info, None)
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.expect("Instance creation error");
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```
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### `Vec<T>` instead of mutable slices
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```rust
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pub fn get_swapchain_images(&self,
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swapchain: vk::SwapchainKHR)
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-> VkResult<Vec<vk::Image>>;
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let present_images = swapchain_loader.get_swapchain_images_khr(swapchain).unwrap();
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```
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*Note*: Functions don't return `Vec<T>` if this would limit the functionality. See `p_next`.
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### Slices
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```rust
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pub fn cmd_pipeline_barrier(&self,
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command_buffer: vk::CommandBuffer,
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src_stage_mask: vk::PipelineStageFlags,
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dst_stage_mask: vk::PipelineStageFlags,
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dependency_flags: vk::DependencyFlags,
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memory_barriers: &[vk::MemoryBarrier],
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buffer_memory_barriers: &[vk::BufferMemoryBarrier],
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image_memory_barriers: &[vk::ImageMemoryBarrier]);
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```
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### Strongly typed handles
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Each Vulkan handle type is exposed as a newtyped struct for improved type safety. Null handles can be constructed with
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`T::null()`, and handles may be freely converted to and from `u64` with `Handle::from_raw` and `Handle::as_raw` for
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interop with non-Ash Vulkan code.
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### Default implementation for all types
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```rust
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// No need to manually set the structure type
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let desc_alloc_info = vk::DescriptorSetAllocateInfo {
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descriptor_pool: self.pool,
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descriptor_set_count: self.layouts.len() as u32,
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p_set_layouts: self.layouts.as_ptr(),
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..Default::default()
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};
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```
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### Builder pattern
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```rust
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// We lose all lifetime information when we call `.build()`. Be careful!
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let queue_info = [vk::DeviceQueueCreateInfo::builder()
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.queue_family_index(queue_family_index)
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.queue_priorities(&priorities)
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.build()];
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// We don't need to call `.build()` here because builders implement `Deref`.
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let device_create_info = vk::DeviceCreateInfo::builder()
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.queue_create_infos(&queue_info)
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.enabled_extension_names(&device_extension_names_raw)
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.enabled_features(&features);
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let device: Device = instance
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.create_device(pdevice, &device_create_info, None)
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.unwrap();
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```
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To not lose this lifetime single items can be "cast" to a slice of length _one_ with `std::slice::from_ref` while still taking advantage of `Deref`:
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```rust
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let queue_info = vk::DeviceQueueCreateInfo::builder()
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.queue_family_index(queue_family_index)
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.queue_priorities(&priorities);
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let device_create_info = vk::DeviceCreateInfo::builder()
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.queue_create_infos(std::slice::from_ref(&queue_info))
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...;
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```
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Builders have an explicit lifetime, and are marked as `#[repr(transparent)]`.
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```rust
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#[repr(transparent)]
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pub struct DeviceCreateInfoBuilder<'a> {
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inner: DeviceCreateInfo,
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marker: ::std::marker::PhantomData<&'a ()>,
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}
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impl<'a> DeviceCreateInfoBuilder<'a> {
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//...
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pub fn queue_create_infos(
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mut self,
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queue_create_infos: &'a [DeviceQueueCreateInfo],
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) -> DeviceCreateInfoBuilder<'a> {...}
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//...
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```
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Every reference has to live as long as the builder itself. Builders implement `Deref` targeting their corresponding Vulkan struct, so references to builders can be passed directly
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to Vulkan functions.
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Calling `.build()` will **discard** that lifetime because Vulkan structs use raw pointers internally. This should be avoided as much as possible because this can easily lead to dangling pointers. If `.build()` has to be called, it should be called as late as possible. [Lifetimes of temporaries](https://doc.rust-lang.org/reference/expressions.html#temporary-lifetimes) are extended to the enclosing statement, ensuring they are valid for the duration of a Vulkan call occurring in the same statement.
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### Pointer chains
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```rust
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let mut variable_pointers = vk::PhysicalDeviceVariablePointerFeatures::builder();
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let mut corner =
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vk::PhysicalDeviceCornerSampledImageFeaturesNV::builder();
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;
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let mut device_create_info = vk::DeviceCreateInfo::builder()
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.push_next(&mut corner)
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.push_next(&mut variable_pointers);
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```
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Pointer chains in builders differ from raw Vulkan. Instead of chaining every struct manually, you instead use `.push_next` on the struct that you are going to pass into the function. Those structs then get *prepended* into the chain.
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`push_next` is also type checked, you can only add valid structs to the chain. Both the structs and the builders can be passed into `push_next`. Only builders for structs that can be passed into functions will implement a `push_next`.
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### Flags and constants as associated constants
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```rust
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// Bitflag
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vk::AccessFlags::COLOR_ATTACHMENT_READ | vk::AccessFlags::COLOR_ATTACHMENT_WRITE
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```
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```rust
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// Constant
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vk::PipelineBindPoint::GRAPHICS,
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```
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### Debug/Display for Flags
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```rust
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let flag = vk::AccessFlags::COLOR_ATTACHMENT_READ
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| vk::AccessFlags::COLOR_ATTACHMENT_WRITE;
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println!("Debug: {:?}", flag);
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println!("Display: {}", flag);
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// Prints:
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// Debug: AccessFlags(110000000)
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// Display: COLOR_ATTACHMENT_READ | COLOR_ATTACHMENT_WRITE
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```
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### Function pointer loading
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Ash also takes care of loading the function pointers. Function pointers are split into 3 categories.
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* Entry: Loads the Vulkan library. Needs to outlive `Instance` and `Device`.
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* Instance: Loads instance level functions. Needs to outlive the `Device`s it has created.
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* Device: Loads device **local** functions.
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The loader is just one possible implementation:
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* Device level functions are retrieved on a per device basis.
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* Everything is loaded by default, functions that failed to load are initialized to a function that always panics.
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* Do not call Vulkan 1.1 functions if you have created a 1.0 instance. Doing so will result in a panic.
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Custom loaders can be implemented.
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### Extension loading
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Additionally, every Vulkan extension has to be loaded explicitly. You can find all extensions under [ash::extensions](https://github.com/MaikKlein/ash/tree/master/ash/src/extensions).
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```rust
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use ash::extensions::khr::Swapchain;
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let swapchain_loader = Swapchain::new(&instance, &device);
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let swapchain = swapchain_loader.create_swapchain(&swapchain_create_info).unwrap();
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```
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### Raw function pointers
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Raw function pointers are available, if something hasn't been exposed yet in the higher level API. Please open an issue if anything is missing.
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```rust
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device.fp_v1_0().destroy_device(...);
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```
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### Support for extension names
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```rust
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use ash::extensions::{Swapchain, XlibSurface, Surface, DebugReport};
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#[cfg(all(unix, not(target_os = "android")))]
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fn extension_names() -> Vec<*const i8> {
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vec![
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Surface::name().as_ptr(),
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XlibSurface::name().as_ptr(),
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DebugReport::name().as_ptr()
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]
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}
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```
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### Implicit handles
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Handles from Instance or Device are passed implicitly.
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```rust
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pub fn create_command_pool(&self,
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create_info: &vk::CommandPoolCreateInfo)
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-> VkResult<vk::CommandPool>;
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let pool = device.create_command_pool(&pool_create_info).unwrap();
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```
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### Optional linking
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The default `loaded` cargo feature will dynamically load the default Vulkan library for the current platform with `Entry::load`, meaning that the build environment does not have to have Vulkan development packages installed.
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If, on the other hand, your application cannot handle Vulkan being missing at runtime, you can instead enable the `linked` feature, which will link your binary with the Vulkan loader directly and expose the infallible `Entry::linked`.
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## Example
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You can find the examples [here](https://github.com/MaikKlein/ash/tree/master/examples).
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All examples currently require: the LunarG Validation layers and a Vulkan library that is visible in your `PATH`. An easy way to get started is to use the [LunarG Vulkan SDK](https://lunarg.com/vulkan-sdk/)
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#### Windows
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Make sure that you have a Vulkan ready driver and install the [LunarG Vulkan SDK](https://lunarg.com/vulkan-sdk/).
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#### Linux
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Make sure that you have a Vulkan ready driver and install the [LunarG Vulkan SDK](https://lunarg.com/vulkan-sdk/). You also have to add the library and layers to your path. Have a look at my [post](http://askubuntu.com/a/803110/77183) if you are unsure how to do that.
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#### macOS
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Install the [LunarG Vulkan SDK](https://lunarg.com/vulkan-sdk/). This basically entails extracting the downloaded tarball to any location you choose and then setting a few environment variables. Specifically, if `SDK_PATH` is set to the root extracted SDK directory,
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* `DYLD_LIBRARY_PATH = $SDK_PATH/macOS/lib`
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* `VK_ICD_FILENAMES = $SDK_PATH/macOS/etc/vulkan/icd.d/MoltenVK_icd.json`
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* `VK_LAYER_PATH = $SDK_PATH/macOS/etc/vulkan/explicit_layer.d`
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### [Triangle](https://github.com/MaikKlein/ash/blob/master/examples/src/bin/triangle.rs)
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Displays a triangle with vertex colors.
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```
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cd examples
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cargo run --bin triangle
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```
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### [Texture](https://github.com/MaikKlein/ash/blob/master/examples/src/bin/texture.rs)
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Displays a texture on a quad.
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```
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cd examples
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cargo run --bin texture
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```
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## Useful resources
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### Examples
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* [vulkan-tutorial-rust](https://github.com/Usami-Renko/vulkan-tutorial-rust) - A port of [vulkan-tutorial.com](https://vulkan-tutorial.com).
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* [ash-sample-progression](https://github.com/bzm3r/ash-sample-progression) - A port of the LunarG examples.
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* [ash-nv-rt](https://github.com/gwihlidal/ash-nv-rt) A raytracing example for ash.
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### Utility libraries
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* [vk-sync](https://github.com/gwihlidal/vk-sync-rs) - Simplified Vulkan synchronization logic, written in rust.
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* [vk-mem-rs](https://github.com/gwihlidal/vk-mem-rs) - This crate provides an FFI layer and idiomatic rust wrappers for the excellent AMD Vulkan Memory Allocator (VMA) C/C++ library.
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* [gpu-allocator](https://github.com/Traverse-Research/gpu-allocator) - Memory allocator written in pure Rust for GPU memory in Vulkan and in the future DirectX 12
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* [lahar](https://github.com/Ralith/lahar) - Tools for asynchronously uploading data to a Vulkan device.
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### Libraries that use ash
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* [gfx-rs](https://github.com/gfx-rs/gfx) - gfx-rs is a low-level, cross-platform graphics abstraction library in Rust.
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## A thanks to
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* [Api with no secrets](https://software.intel.com/en-us/articles/api-without-secrets-introduction-to-vulkan-part-1)
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* [Vulkan tutorial](http://jhenriques.net/development.html)
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* [Vulkan examples](https://github.com/SaschaWillems/Vulkan)
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* [Vulkan tutorial](https://vulkan-tutorial.com/)
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* [Vulkano](https://github.com/vulkano-rs/vulkano)
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* [vk-rs](https://github.com/Osspial/vk-rs)
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