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//! Items related to the **Frame** type, describing a single frame of graphics for a single window.
use crate::color::IntoLinSrgba;
use crate::wgpu;
use std::ops;
use std::path::PathBuf;
use std::sync::Mutex;
use std::time::Duration;
pub mod raw;
pub use self::raw::RawFrame;
/// A **Frame** to which the user can draw graphics before it is presented to the display.
///
/// **Frame**s are delivered to the user for drawing via the user's **view** function.
///
/// See the **RawFrame** docs for more details on how the implementation works under the hood. The
/// **Frame** type differs in that rather than drawing directly to the swapchain image the user may
/// draw to an intermediary linear sRGBA image. There are several advantages of drawing to an
/// intermediary image.
pub struct Frame<'swap_chain> {
raw_frame: RawFrame<'swap_chain>,
render_data: &'swap_chain RenderData,
capture_data: &'swap_chain CaptureData,
}
/// Data specific to the intermediary textures.
#[derive(Debug)]
pub struct RenderData {
intermediary_lin_srgba: IntermediaryLinSrgba,
msaa_samples: u32,
size: [u32; 2],
// For writing the intermediary linear sRGBA texture to the swap chain texture.
texture_reshaper: wgpu::TextureReshaper,
}
/// Data related to the capturing of a frame.
#[derive(Debug)]
pub(crate) struct CaptureData {
// If `Some`, indicates a path to which the current frame should be written.
pub(crate) next_frame_path: Mutex<Option<PathBuf>>,
// The `TextureCapturer` used to capture the frame.
pub(crate) texture_capturer: wgpu::TextureCapturer,
}
/// Intermediary textures used as a target before resolving multisampling and writing to the
/// swapchain texture.
#[derive(Debug)]
pub(crate) struct IntermediaryLinSrgba {
msaa_texture: Option<(wgpu::Texture, wgpu::TextureView)>,
texture: wgpu::Texture,
texture_view: wgpu::TextureView,
}
impl<'swap_chain> ops::Deref for Frame<'swap_chain> {
type Target = RawFrame<'swap_chain>;
fn deref(&self) -> &Self::Target {
&self.raw_frame
}
}
impl<'swap_chain> Frame<'swap_chain> {
/// The default number of multisample anti-aliasing samples used if the window with which the
/// `Frame` is associated supports it.
pub const DEFAULT_MSAA_SAMPLES: u32 = 4;
/// The texture format used by the intermediary linear sRGBA image.
///
/// We use a high bit depth format in order to retain as much information as possible when
/// converting from the linear representation to the swapchain format (normally a non-linear
/// representation).
// TODO: Kvark recommends trying `Rgb10A2Unorm`.
pub const TEXTURE_FORMAT: wgpu::TextureFormat =
wgpu::RenderPipelineBuilder::DEFAULT_COLOR_FORMAT;
// Initialise a new empty frame ready for "drawing".
pub(crate) fn new_empty(
raw_frame: RawFrame<'swap_chain>,
render_data: &'swap_chain RenderData,
capture_data: &'swap_chain CaptureData,
) -> Self {
Frame {
raw_frame,
render_data,
capture_data,
}
}
// The private implementation of `submit`, allowing it to be called during `drop` if submission
// has not yet occurred.
fn submit_inner(&mut self) {
let Frame {
ref capture_data,
ref render_data,
ref mut raw_frame,
} = *self;
// Resolve the MSAA if necessary.
if let Some((_, ref msaa_texture_view)) = render_data.intermediary_lin_srgba.msaa_texture {
let mut encoder = raw_frame.command_encoder();
wgpu::resolve_texture(
msaa_texture_view,
&render_data.intermediary_lin_srgba.texture_view,
&mut *encoder,
);
}
// Check to see if the user specified capturing the frame.
let mut snapshot_capture = None;
if let Ok(mut guard) = capture_data.next_frame_path.lock() {
if let Some(path) = guard.take() {
let device = raw_frame.device_queue_pair().device();
let mut encoder = raw_frame.command_encoder();
let snapshot = capture_data.texture_capturer.capture(
device,
&mut *encoder,
&render_data.intermediary_lin_srgba.texture,
);
snapshot_capture = Some((path, snapshot));
}
}
// Convert the linear sRGBA image to the swapchain image.
//
// To do so, we sample the linear sRGBA image and draw it to the swapchain image using
// two triangles and a fragment shader.
{
let mut encoder = raw_frame.command_encoder();
render_data
.texture_reshaper
.encode_render_pass(raw_frame.swap_chain_texture(), &mut *encoder);
}
// Submit all commands on the device queue.
raw_frame.submit_inner();
// If the user did specify capturing the frame, submit the asynchronous read.
if let Some((path, snapshot)) = snapshot_capture {
let result = snapshot.read(move |result| match result {
// TODO: Log errors, don't print to stderr.
Err(e) => eprintln!("failed to async read captured frame: {:?}", e),
Ok(image) => {
let image = image.to_owned();
if let Err(e) = image.save(&path) {
// TODO: Log errors, don't print to stderr.
eprintln!(
"failed to save captured frame to \"{}\": {}",
path.display(),
e
);
}
}
});
if let Err(wgpu::TextureCapturerAwaitWorkerTimeout(_)) = result {
// TODO: Log errors, don't print to stderr.
eprintln!("timed out while waiting for a worker thread to capture the frame");
}
}
}
/// The texture to which all graphics should be drawn this frame.
///
/// This is **not** the swapchain texture, but rather an intermediary linear sRGBA image. This
/// intermediary image is used in order to:
///
/// - Ensure consistent MSAA resolve behaviour across platforms.
/// - Avoid the need for multiple implicit conversions to and from linear sRGBA for each
/// graphics pipeline render pass that is used.
/// - Allow for the user's rendered image to persist between frames.
///
/// The exact format of the texture is equal to `Frame::TEXTURE_FORMAT`.
///
/// If the number of MSAA samples specified is greater than `1` (which it is by default if
/// supported by the platform), this will be a multisampled texture. After the **view**
/// function returns, this texture will be resolved to a non-multisampled linear sRGBA texture.
/// After the texture has been resolved if necessary, it will then be used as a shader input
/// within a graphics pipeline used to draw the swapchain texture.
pub fn texture(&self) -> &wgpu::Texture {
self.render_data
.intermediary_lin_srgba
.msaa_texture
.as_ref()
.map(|(tex, _)| tex)
.unwrap_or(&self.render_data.intermediary_lin_srgba.texture)
}
/// A full view into the frame's texture.
///
/// See `texture` for details.
pub fn texture_view(&self) -> &wgpu::TextureView {
self.render_data.texture_view()
}
/// Returns the resolve target texture in the case that MSAA is enabled.
pub fn resolve_target(&self) -> Option<&wgpu::TextureView> {
if self.render_data.msaa_samples <= 1 {
None
} else {
Some(&self.render_data.intermediary_lin_srgba.texture_view)
}
}
/// The color format of the `Frame`'s intermediary linear sRGBA texture (equal to
/// `Frame::TEXTURE_FORMAT`).
pub fn texture_format(&self) -> wgpu::TextureFormat {
Self::TEXTURE_FORMAT
}
/// The number of MSAA samples of the `Frame`'s intermediary linear sRGBA texture.
pub fn texture_msaa_samples(&self) -> u32 {
self.render_data.msaa_samples
}
/// The size of the frame's texture in pixels.
pub fn texture_size(&self) -> [u32; 2] {
self.render_data.size
}
/// Short-hand for constructing a `wgpu::RenderPassColorAttachment` for use within a
/// render pass that targets this frame's texture. The returned descriptor's `attachment` will
/// the same `wgpu::TextureView` returned by the `Frame::texture` method.
///
/// Note that this method will not perform any resolving. In the case that `msaa_samples` is
/// greater than `1`, a render pass will be automatically added after the `view` completes and
/// before the texture is drawn to the swapchain.
pub fn color_attachment_descriptor(&self) -> wgpu::RenderPassColorAttachment {
let load = wgpu::LoadOp::Load;
let store = true;
let attachment = match self.render_data.intermediary_lin_srgba.msaa_texture {
None => &self.render_data.intermediary_lin_srgba.texture_view,
Some((_, ref msaa_texture_view)) => msaa_texture_view,
};
let resolve_target = None;
wgpu::RenderPassColorAttachment {
view: attachment,
resolve_target,
ops: wgpu::Operations { load, store },
}
}
/// Clear the texture with the given color.
pub fn clear<C>(&self, color: C)
where
C: IntoLinSrgba<f32>,
{
let lin_srgba = color.into_lin_srgba();
let (r, g, b, a) = lin_srgba.into_components();
let (r, g, b, a) = (r as f64, g as f64, b as f64, a as f64);
let color = wgpu::Color { r, g, b, a };
self.raw_frame.clear(self.texture_view(), color);
}
/// Submit the frame to the GPU!
///
/// Note that you do not need to call this manually as submission will occur automatically when
/// the **Frame** is dropped.
///
/// Before submission, the frame does the following:
///
/// - If the frame's intermediary linear sRGBA texture is multisampled, resolve it.
/// - Write the intermediary linear sRGBA image to the swap chain texture.
///
/// It can sometimes be useful to submit the **Frame** before `view` completes in order to read
/// the frame's texture back to the CPU (e.g. for screen shots, recordings, etc).
pub fn submit(mut self) {
self.submit_inner();
}
}
impl CaptureData {
pub(crate) fn new(max_jobs: u32, timeout: Option<Duration>) -> Self {
CaptureData {
next_frame_path: Default::default(),
texture_capturer: wgpu::TextureCapturer::new(Some(max_jobs), timeout),
}
}
}
impl RenderData {
/// Initialise the render data.
///
/// Creates an `wgpu::TextureView` with the given parameters.
///
/// If `msaa_samples` is greater than 1 a `multisampled` texture will also be created. Otherwise the
/// a regular non-multisampled image will be created.
pub(crate) fn new(
device: &wgpu::Device,
swap_chain_dims: [u32; 2],
swap_chain_format: wgpu::TextureFormat,
msaa_samples: u32,
) -> Self {
let intermediary_lin_srgba =
create_intermediary_lin_srgba(device, swap_chain_dims, msaa_samples);
let src_sample_count = 1;
let swap_chain_sample_count = 1;
let texture_reshaper = wgpu::TextureReshaper::new(
device,
&intermediary_lin_srgba.texture_view,
src_sample_count,
intermediary_lin_srgba.texture_view.sample_type(),
swap_chain_sample_count,
swap_chain_format,
);
RenderData {
intermediary_lin_srgba,
texture_reshaper,
size: swap_chain_dims,
msaa_samples,
}
}
/// A full view into the associated texture.
///
/// See `texture` for details.
pub(crate) fn texture_view(&self) -> &wgpu::TextureView {
self.intermediary_lin_srgba
.msaa_texture
.as_ref()
.map(|(_, view)| view)
.unwrap_or(&self.intermediary_lin_srgba.texture_view)
}
}
impl<'swap_chain> Drop for Frame<'swap_chain> {
fn drop(&mut self) {
if !self.raw_frame.is_submitted() {
self.submit_inner();
}
}
}
fn create_lin_srgba_msaa_texture(
device: &wgpu::Device,
swap_chain_dims: [u32; 2],
msaa_samples: u32,
) -> wgpu::Texture {
wgpu::TextureBuilder::new()
.size(swap_chain_dims)
.sample_count(msaa_samples)
.usage(wgpu::TextureUsages::RENDER_ATTACHMENT)
.format(Frame::TEXTURE_FORMAT)
.build(device)
}
fn create_lin_srgba_texture(device: &wgpu::Device, swap_chain_dims: [u32; 2]) -> wgpu::Texture {
wgpu::TextureBuilder::new()
.size(swap_chain_dims)
.format(Frame::TEXTURE_FORMAT)
.usage(wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING)
.build(device)
}
fn create_intermediary_lin_srgba(
device: &wgpu::Device,
swap_chain_dims: [u32; 2],
msaa_samples: u32,
) -> IntermediaryLinSrgba {
let msaa_texture = match msaa_samples {
0 | 1 => None,
_ => {
let texture = create_lin_srgba_msaa_texture(device, swap_chain_dims, msaa_samples);
let texture_view = texture.view().build();
Some((texture, texture_view))
}
};
let texture = create_lin_srgba_texture(device, swap_chain_dims);
let texture_view = texture.view().build();
IntermediaryLinSrgba {
msaa_texture,
texture,
texture_view,
}
}