Ash

A very lightweight wrapper around Vulkan

Overview

• A true Vulkan API without compromises
• Convenience features without limiting functionality
• Additional type safety
• Device local function pointer loading
• No validation, everything is unsafe
• Generated from vk.xml
• Support for Vulkan 1.1

Features

Explicit returns with Result

// function signature
pub fn create_instance(&self,
                       create_info: &vk::InstanceCreateInfo,
                       allocation_callbacks: Option<&vk::AllocationCallbacks>)
                       -> Result<Instance, InstanceError> { .. }
let instance = entry.create_instance(&create_info, None)
    .expect("Instance creation error");

Vec<T> instead of mutable slices

pub fn get_swapchain_images(&self,
                            swapchain: vk::SwapchainKHR)
                            -> VkResult<Vec<vk::Image>>;
let present_images = swapchain_loader.get_swapchain_images_khr(swapchain).unwrap();

Note: Functions don't return Vec<T> if this would limit the functionality. See p_next.

Slices

pub fn cmd_pipeline_barrier(&self,
                            command_buffer: vk::CommandBuffer,
                            src_stage_mask: vk::PipelineStageFlags,
                            dst_stage_mask: vk::PipelineStageFlags,
                            dependency_flags: vk::DependencyFlags,
                            memory_barriers: &[vk::MemoryBarrier],
                            buffer_memory_barriers: &[vk::BufferMemoryBarrier],
                            image_memory_barriers: &[vk::ImageMemoryBarrier]);

Strongly typed handles

Each Vulkan handle type is exposed as a newtyped struct for improved type safety. Null handles can be constructed with T::null(), and handles may be freely converted to and from u64 with Handle::from_raw and Handle::as_raw for interop with non-Ash Vulkan code.

Default implementation for all types

// No need to manually set the structure type
let desc_alloc_info = vk::DescriptorSetAllocateInfo {
    descriptor_pool: self.pool,
    descriptor_set_count: self.layouts.len() as u32,
    p_set_layouts: self.layouts.as_ptr(),
    ..Default::default()
};

Builder pattern

let pipeline_vertex_input_state_create_info = vk::PipelineVertexInputStateCreateInfo::builder()
    .vertex_binding_descriptions(&Vertex::binding_descriptions())
    .vertex_attribute_descriptions(&Vertex::attribute_descriptions()).build();

Builders implement Deref targeting their corresponding Vulkan struct, so references to builders can be passed directly to Vulkan functions. This is encouraged as doing so allows Rust to check the lifetimes of captured objects are valid, whereas calling build discards lifetime information, making inadvertent use-after-free errors more likely.

Flags and constants as associated constants

// Bitflag
vk::AccessFlags::COLOR_ATTACHMENT_READ | vk::AccessFlags::COLOR_ATTACHMENT_WRITE

// Constant
vk::PipelineBindPoint::GRAPHICS,

Debug/Display for Flags

let flag = vk::AccessFlags::COLOR_ATTACHMENT_READ
        | vk::AccessFlags::COLOR_ATTACHMENT_WRITE;
println!("Debug: {:?}", flag);
println!("Display: {}", flag);
// Prints:
// Debug: AccessFlags(110000000)
// Display: COLOR_ATTACHMENT_READ | COLOR_ATTACHMENT_WRITE

Function pointer loading

Ash also takes care of loading the function pointers. Function pointers are split into 3 categories.

• Entry: Loads the Vulkan library. Needs to outlive Instance and Device.
• Instance: Loads instance level functions. Needs to outlive the Devices it has created.
• Device: Loads device local functions.

The loader is just one possible implementation:

• Device level functions are retrieved on a per device basis.
• Everything is loaded by default, functions that failed to load are initialized to a function that always panics.
• Do not call Vulkan 1.1 functions if you have created a 1.0 instance. Doing so will result in a panic.

Custom loaders can be implemented.

Extension loading

Additionally, every Vulkan extension has to be loaded explicitly. You can find all extensions under ash::extensions.

use ash::extensions::khr::Swapchain;
let swapchain_loader = Swapchain::new(&instance, &device);
let swapchain = swapchain_loader.create_swapchain(&swapchain_create_info).unwrap();

Raw function pointers

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.

device.fp_v1_0().destroy_device(...);

Support for extension names

use ash::extensions::{Swapchain, XlibSurface, Surface, DebugReport};
#[cfg(all(unix, not(target_os = "android")))]
fn extension_names() -> Vec<*const i8> {
    vec![
        Surface::name().as_ptr(),
        XlibSurface::name().as_ptr(),
        DebugReport::name().as_ptr()
    ]
}

Implicit handles

Handles from Instance or Device are passed implicitly.

pub fn create_command_pool(&self,
                           create_info: &vk::CommandPoolCreateInfo)
                           -> VkResult<vk::CommandPool>;

let pool = device.create_command_pool(&pool_create_info).unwrap();

Example

You can find the examples here. 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

Windows

Make sure that you have a Vulkan ready driver and install the LunarG Vulkan SDK.

Linux

Make sure that you have a Vulkan ready driver and install the LunarG Vulkan SDK. You also have to add the library and layers to your path. Have a look at my post if you are unsure how to do that.

Triangle

Displays a triangle with vertex colors.

cd examples
cargo run --bin triangle

macOS

Install the LunarG 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,

• DYLD_LIBRARY_PATH = $SDK_PATH/macOS/lib
• VK_ICD_FILENAMES = $SDK_PATH/macOS/etc/vulkan/icd.d/MoltenVK_icd.json
• VK_LAYER_PATH = $SDK_PATH/macOS/etc/vulkan/explicit_layer.d

Texture

Displays a texture on a quad.

cd examples
cargo run --bin texture

Useful resources

Examples

• vulkan-tutorial-rust - A port of vulkan-tutorial.com.
• ash-sample-progression - A port of the LunarG examples.
• ash-nv-rt A raytracing example for ash.

Utility libraries

• vk-sync - Simplified Vulkan synchronization logic, written in rust.
• vk-mem-rs - This crate provides an FFI layer and idiomatic rust wrappers for the excellent AMD Vulkan Memory Allocator (VMA) C/C++ library.
• lahar - Tools for asynchronously uploading data to a Vulkan device.

Libraries that use ash

• gfx-rs - gfx-rs is a low-level, cross-platform graphics abstraction library in Rust.

A thanks to

• Api with no secrets
• Vulkan tutorial
• Vulkan examples
• Vulkan tutorial
• Vulkano
• vk-rs