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// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.
// Welcome to the triangle example!
//
// This is the only example that is entirely detailed. All the other examples avoid code
// duplication by using helper functions.
//
// This example assumes that you are already more or less familiar with graphics programming
// and that you want to learn Vulkan. This means that for example it won't go into details about
// what a vertex or a shader is.
use vulkano::buffer::{BufferUsage, CpuAccessibleBuffer};
use vulkano::command_buffer::{AutoCommandBufferBuilder, DynamicState};
use vulkano::device::{Device, DeviceExtensions};
use vulkano::framebuffer::{Framebuffer, FramebufferAbstract, Subpass, RenderPassAbstract};
use vulkano::image::SwapchainImage;
use vulkano::instance::{Instance, PhysicalDevice};
use vulkano::pipeline::GraphicsPipeline;
use vulkano::pipeline::viewport::Viewport;
use vulkano::swapchain::{AcquireError, PresentMode, SurfaceTransform, Swapchain, SwapchainCreationError, ColorSpace};
use vulkano::swapchain;
use vulkano::sync::{GpuFuture, FlushError};
use vulkano::sync;
use vulkano_win::VkSurfaceBuild;
use winit::window::{WindowBuilder, Window};
use winit::event_loop::{EventLoop, ControlFlow};
use winit::event::{Event, WindowEvent};
use std::sync::Arc;
fn main() {
// The first step of any Vulkan program is to create an instance.
//
// When we create an instance, we have to pass a list of extensions that we want to enable.
//
// All the window-drawing functionalities are part of non-core extensions that we need
// to enable manually. To do so, we ask the `vulkano_win` crate for the list of extensions
// required to draw to a window.
let required_extensions = vulkano_win::required_extensions();
// Now creating the instance.
let instance = Instance::new(None, &required_extensions, None).unwrap();
// We then choose which physical device to use.
//
// In a real application, there are three things to take into consideration:
//
// - Some devices may not support some of the optional features that may be required by your
// application. You should filter out the devices that don't support your app.
//
// - Not all devices can draw to a certain surface. Once you create your window, you have to
// choose a device that is capable of drawing to it.
//
// - You probably want to leave the choice between the remaining devices to the user.
//
// For the sake of the example we are just going to use the first device, which should work
// most of the time.
let physical = PhysicalDevice::enumerate(&instance).next().unwrap();
// Some little debug infos.
println!("Using device: {} (type: {:?})", physical.name(), physical.ty());
// The objective of this example is to draw a triangle on a window. To do so, we first need to
// create the window.
//
// This is done by creating a `WindowBuilder` from the `winit` crate, then calling the
// `build_vk_surface` method provided by the `VkSurfaceBuild` trait from `vulkano_win`. If you
// ever get an error about `build_vk_surface` being undefined in one of your projects, this
// probably means that you forgot to import this trait.
//
// This returns a `vulkano::swapchain::Surface` object that contains both a cross-platform winit
// window and a cross-platform Vulkan surface that represents the surface of the window.
let event_loop = EventLoop::new();
let surface = WindowBuilder::new().build_vk_surface(&event_loop, instance.clone()).unwrap();
// The next step is to choose which GPU queue will execute our draw commands.
//
// Devices can provide multiple queues to run commands in parallel (for example a draw queue
// and a compute queue), similar to CPU threads. This is something you have to have to manage
// manually in Vulkan.
//
// In a real-life application, we would probably use at least a graphics queue and a transfers
// queue to handle data transfers in parallel. In this example we only use one queue.
//
// We have to choose which queues to use early on, because we will need this info very soon.
let queue_family = physical.queue_families().find(|&q| {
// We take the first queue that supports drawing to our window.
q.supports_graphics() && surface.is_supported(q).unwrap_or(false)
}).unwrap();
// Now initializing the device. This is probably the most important object of Vulkan.
//
// We have to pass five parameters when creating a device:
//
// - Which physical device to connect to.
//
// - A list of optional features and extensions that our program needs to work correctly.
// Some parts of the Vulkan specs are optional and must be enabled manually at device
// creation. In this example the only thing we are going to need is the `khr_swapchain`
// extension that allows us to draw to a window.
//
// - A list of layers to enable. This is very niche, and you will usually pass `None`.
//
// - The list of queues that we are going to use. The exact parameter is an iterator whose
// items are `(Queue, f32)` where the floating-point represents the priority of the queue
// between 0.0 and 1.0. The priority of the queue is a hint to the implementation about how
// much it should prioritize queues between one another.
//
// The list of created queues is returned by the function alongside with the device.
let device_ext = DeviceExtensions { khr_swapchain: true, .. DeviceExtensions::none() };
let (device, mut queues) = Device::new(physical, physical.supported_features(), &device_ext,
[(queue_family, 0.5)].iter().cloned()).unwrap();
// Since we can request multiple queues, the `queues` variable is in fact an iterator. In this
// example we use only one queue, so we just retrieve the first and only element of the
// iterator and throw it away.
let queue = queues.next().unwrap();
// Before we can draw on the surface, we have to create what is called a swapchain. Creating
// a swapchain allocates the color buffers that will contain the image that will ultimately
// be visible on the screen. These images are returned alongside with the swapchain.
let (mut swapchain, images) = {
// Querying the capabilities of the surface. When we create the swapchain we can only
// pass values that are allowed by the capabilities.
let caps = surface.capabilities(physical).unwrap();
let usage = caps.supported_usage_flags;
// The alpha mode indicates how the alpha value of the final image will behave. For example
// you can choose whether the window will be opaque or transparent.
let alpha = caps.supported_composite_alpha.iter().next().unwrap();
// Choosing the internal format that the images will have.
let format = caps.supported_formats[0].0;
// The dimensions of the window, only used to initially setup the swapchain.
// NOTE:
// On some drivers the swapchain dimensions are specified by `caps.current_extent` and the
// swapchain size must use these dimensions.
// These dimensions are always the same as the window dimensions
//
// However other drivers dont specify a value i.e. `caps.current_extent` is `None`
// These drivers will allow anything but the only sensible value is the window dimensions.
//
// Because for both of these cases, the swapchain needs to be the window dimensions, we just use that.
let dimensions: [u32; 2] = surface.window().inner_size().into();
// Please take a look at the docs for the meaning of the parameters we didn't mention.
Swapchain::new(device.clone(), surface.clone(), caps.min_image_count, format,
dimensions, 1, usage, &queue, SurfaceTransform::Identity, alpha,
PresentMode::Fifo, true, ColorSpace::SrgbNonLinear).unwrap()
};
// We now create a buffer that will store the shape of our triangle.
let vertex_buffer = {
#[derive(Default, Debug, Clone)]
struct Vertex { position: [f32; 2] }
vulkano::impl_vertex!(Vertex, position);
CpuAccessibleBuffer::from_iter(device.clone(), BufferUsage::all(), [
Vertex { position: [-0.5, -0.25] },
Vertex { position: [0.0, 0.5] },
Vertex { position: [0.25, -0.1] }
].iter().cloned()).unwrap()
};
// The next step is to create the shaders.
//
// The raw shader creation API provided by the vulkano library is unsafe, for various reasons.
//
// An overview of what the `vulkano_shaders::shader!` macro generates can be found in the
// `vulkano-shaders` crate docs. You can view them at https://docs.rs/vulkano-shaders/
//
// TODO: explain this in details
mod vs {
vulkano_shaders::shader!{
ty: "vertex",
src: "
#version 450
layout(location = 0) in vec2 position;
void main() {
gl_Position = vec4(position, 0.0, 1.0);
}
"
}
}
mod fs {
vulkano_shaders::shader!{
ty: "fragment",
src: "
#version 450
layout(location = 0) out vec4 f_color;
void main() {
f_color = vec4(1.0, 0.0, 0.0, 1.0);
}
"
}
}
let vs = vs::Shader::load(device.clone()).unwrap();
let fs = fs::Shader::load(device.clone()).unwrap();
// At this point, OpenGL initialization would be finished. However in Vulkan it is not. OpenGL
// implicitly does a lot of computation whenever you draw. In Vulkan, you have to do all this
// manually.
// The next step is to create a *render pass*, which is an object that describes where the
// output of the graphics pipeline will go. It describes the layout of the images
// where the colors, depth and/or stencil information will be written.
let render_pass = Arc::new(vulkano::single_pass_renderpass!(
device.clone(),
attachments: {
// `color` is a custom name we give to the first and only attachment.
color: {
// `load: Clear` means that we ask the GPU to clear the content of this
// attachment at the start of the drawing.
load: Clear,
// `store: Store` means that we ask the GPU to store the output of the draw
// in the actual image. We could also ask it to discard the result.
store: Store,
// `format: <ty>` indicates the type of the format of the image. This has to
// be one of the types of the `vulkano::format` module (or alternatively one
// of your structs that implements the `FormatDesc` trait). Here we use the
// same format as the swapchain.
format: swapchain.format(),
// TODO:
samples: 1,
}
},
pass: {
// We use the attachment named `color` as the one and only color attachment.
color: [color],
// No depth-stencil attachment is indicated with empty brackets.
depth_stencil: {}
}
).unwrap());
// Before we draw we have to create what is called a pipeline. This is similar to an OpenGL
// program, but much more specific.
let pipeline = Arc::new(GraphicsPipeline::start()
// We need to indicate the layout of the vertices.
// The type `SingleBufferDefinition` actually contains a template parameter corresponding
// to the type of each vertex. But in this code it is automatically inferred.
.vertex_input_single_buffer()
// A Vulkan shader can in theory contain multiple entry points, so we have to specify
// which one. The `main` word of `main_entry_point` actually corresponds to the name of
// the entry point.
.vertex_shader(vs.main_entry_point(), ())
// The content of the vertex buffer describes a list of triangles.
.triangle_list()
// Use a resizable viewport set to draw over the entire window
.viewports_dynamic_scissors_irrelevant(1)
// See `vertex_shader`.
.fragment_shader(fs.main_entry_point(), ())
// We have to indicate which subpass of which render pass this pipeline is going to be used
// in. The pipeline will only be usable from this particular subpass.
.render_pass(Subpass::from(render_pass.clone(), 0).unwrap())
// Now that our builder is filled, we call `build()` to obtain an actual pipeline.
.build(device.clone())
.unwrap());
// Dynamic viewports allow us to recreate just the viewport when the window is resized
// Otherwise we would have to recreate the whole pipeline.
let mut dynamic_state = DynamicState { line_width: None, viewports: None, scissors: None, compare_mask: None, write_mask: None, reference: None };
// The render pass we created above only describes the layout of our framebuffers. Before we
// can draw we also need to create the actual framebuffers.
//
// Since we need to draw to multiple images, we are going to create a different framebuffer for
// each image.
let mut framebuffers = window_size_dependent_setup(&images, render_pass.clone(), &mut dynamic_state);
// Initialization is finally finished!
// In some situations, the swapchain will become invalid by itself. This includes for example
// when the window is resized (as the images of the swapchain will no longer match the
// window's) or, on Android, when the application went to the background and goes back to the
// foreground.
//
// In this situation, acquiring a swapchain image or presenting it will return an error.
// Rendering to an image of that swapchain will not produce any error, but may or may not work.
// To continue rendering, we need to recreate the swapchain by creating a new swapchain.
// Here, we remember that we need to do this for the next loop iteration.
let mut recreate_swapchain = false;
// In the loop below we are going to submit commands to the GPU. Submitting a command produces
// an object that implements the `GpuFuture` trait, which holds the resources for as long as
// they are in use by the GPU.
//
// Destroying the `GpuFuture` blocks until the GPU is finished executing it. In order to avoid
// that, we store the submission of the previous frame here.
let mut previous_frame_end = Some(Box::new(sync::now(device.clone())) as Box<dyn GpuFuture>);
event_loop.run(move |event, _, control_flow| {
match event {
Event::WindowEvent { event: WindowEvent::CloseRequested, .. } => {
*control_flow = ControlFlow::Exit;
},
Event::WindowEvent { event: WindowEvent::Resized(_), .. } => {
recreate_swapchain = true;
},
Event::RedrawEventsCleared => {
// It is important to call this function from time to time, otherwise resources will keep
// accumulating and you will eventually reach an out of memory error.
// Calling this function polls various fences in order to determine what the GPU has
// already processed, and frees the resources that are no longer needed.
previous_frame_end.as_mut().unwrap().cleanup_finished();
// Whenever the window resizes we need to recreate everything dependent on the window size.
// In this example that includes the swapchain, the framebuffers and the dynamic state viewport.
if recreate_swapchain {
// Get the new dimensions of the window.
let dimensions: [u32; 2] = surface.window().inner_size().into();
let (new_swapchain, new_images) = match swapchain.recreate_with_dimension(dimensions) {
Ok(r) => r,
// This error tends to happen when the user is manually resizing the window.
// Simply restarting the loop is the easiest way to fix this issue.
Err(SwapchainCreationError::UnsupportedDimensions) => return,
Err(e) => panic!("Failed to recreate swapchain: {:?}", e)
};
swapchain = new_swapchain;
// Because framebuffers contains an Arc on the old swapchain, we need to
// recreate framebuffers as well.
framebuffers = window_size_dependent_setup(&new_images, render_pass.clone(), &mut dynamic_state);
recreate_swapchain = false;
}
// Before we can draw on the output, we have to *acquire* an image from the swapchain. If
// no image is available (which happens if you submit draw commands too quickly), then the
// function will block.
// This operation returns the index of the image that we are allowed to draw upon.
//
// This function can block if no image is available. The parameter is an optional timeout
// after which the function call will return an error.
let (image_num, acquire_future) = match swapchain::acquire_next_image(swapchain.clone(), None) {
Ok(r) => r,
Err(AcquireError::OutOfDate) => {
recreate_swapchain = true;
return;
},
Err(e) => panic!("Failed to acquire next image: {:?}", e)
};
// Specify the color to clear the framebuffer with i.e. blue
let clear_values = vec!([0.0, 0.0, 1.0, 1.0].into());
// In order to draw, we have to build a *command buffer*. The command buffer object holds
// the list of commands that are going to be executed.
//
// Building a command buffer is an expensive operation (usually a few hundred
// microseconds), but it is known to be a hot path in the driver and is expected to be
// optimized.
//
// Note that we have to pass a queue family when we create the command buffer. The command
// buffer will only be executable on that given queue family.
let command_buffer = AutoCommandBufferBuilder::primary_one_time_submit(device.clone(), queue.family()).unwrap()
// Before we can draw, we have to *enter a render pass*. There are two methods to do
// this: `draw_inline` and `draw_secondary`. The latter is a bit more advanced and is
// not covered here.
//
// The third parameter builds the list of values to clear the attachments with. The API
// is similar to the list of attachments when building the framebuffers, except that
// only the attachments that use `load: Clear` appear in the list.
.begin_render_pass(framebuffers[image_num].clone(), false, clear_values).unwrap()
// We are now inside the first subpass of the render pass. We add a draw command.
//
// The last two parameters contain the list of resources to pass to the shaders.
// Since we used an `EmptyPipeline` object, the objects have to be `()`.
.draw(pipeline.clone(), &dynamic_state, vertex_buffer.clone(), (), ()).unwrap()
// We leave the render pass by calling `draw_end`. Note that if we had multiple
// subpasses we could have called `next_inline` (or `next_secondary`) to jump to the
// next subpass.
.end_render_pass().unwrap()
// Finish building the command buffer by calling `build`.
.build().unwrap();
let future = previous_frame_end.take().unwrap()
.join(acquire_future)
.then_execute(queue.clone(), command_buffer).unwrap()
// The color output is now expected to contain our triangle. But in order to show it on
// the screen, we have to *present* the image by calling `present`.
//
// This function does not actually present the image immediately. Instead it submits a
// present command at the end of the queue. This means that it will only be presented once
// the GPU has finished executing the command buffer that draws the triangle.
.then_swapchain_present(queue.clone(), swapchain.clone(), image_num)
.then_signal_fence_and_flush();
match future {
Ok(future) => {
previous_frame_end = Some(Box::new(future) as Box<_>);
},
Err(FlushError::OutOfDate) => {
recreate_swapchain = true;
previous_frame_end = Some(Box::new(sync::now(device.clone())) as Box<_>);
}
Err(e) => {
println!("Failed to flush future: {:?}", e);
previous_frame_end = Some(Box::new(sync::now(device.clone())) as Box<_>);
}
}
},
_ => ()
}
});
}
/// This method is called once during initialization, then again whenever the window is resized
fn window_size_dependent_setup(
images: &[Arc<SwapchainImage<Window>>],
render_pass: Arc<dyn RenderPassAbstract + Send + Sync>,
dynamic_state: &mut DynamicState
) -> Vec<Arc<dyn FramebufferAbstract + Send + Sync>> {
let dimensions = images[0].dimensions();
let viewport = Viewport {
origin: [0.0, 0.0],
dimensions: [dimensions[0] as f32, dimensions[1] as f32],
depth_range: 0.0 .. 1.0,
};
dynamic_state.viewports = Some(vec!(viewport));
images.iter().map(|image| {
Arc::new(
Framebuffer::start(render_pass.clone())
.add(image.clone()).unwrap()
.build().unwrap()
) as Arc<dyn FramebufferAbstract + Send + Sync>
}).collect::<Vec<_>>()
}
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