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//! A tiny library providing a GPU-powered pixel buffer.
//!
//! [`Pixels`] represents a 2D pixel buffer with an explicit image resolution, making it ideal for
//! prototyping simple pixel-based games, animations, and emulators. The pixel buffer is rendered
//! entirely on the GPU, allowing developers to easily incorporate special effects with shaders and
//! a customizable pipeline.
//!
//! The GPU interface is offered by [`wgpu`](https://crates.io/crates/wgpu), and is re-exported for
//! your convenience. Use a windowing framework or context manager of your choice;
//! [`winit`](https://crates.io/crates/winit) is a good place to start. Any windowing framework that
//! uses [`raw-window-handle`](https://crates.io/crates/raw-window-handle) will work.
//!
//! # Environment variables
//!
//! Pixels will default to selecting the most powerful GPU and most modern graphics API available on
//! the system, and these choices can be overridden with environment variables. These are the same
//! vars supported by the [`wgpu` examples](https://github.com/gfx-rs/wgpu/tree/v0.10/wgpu#usage).
//!
//! * `WGPU_BACKEND`: Select the backend (aka graphics API).
//! * Supported values: `vulkan`, `metal`, `dx11`, `dx12`, `gl`, `webgpu`
//! * The default depends on capabilities of the host system, with `vulkan` being preferred on
//! Linux and Windows, and `metal` preferred on macOS.
//! * `WGPU_ADAPTER_NAME`: Select an adapter (aka GPU) with substring matching.
//! * E.g. `1080` will match `NVIDIA GeForce 1080ti`
//! * `WGPU_POWER_PREF`: Select an adapter (aka GPU) that meets the given power profile.
//! * Supported values: `low`, `high`
//! * The default is `low`. I.e. an integrated GPU will be preferred over a discrete GPU.
//!
//! Note that `WGPU_ADAPTER_NAME` and `WGPU_POWER_PREF` are mutually exclusive and that
//! `WGPU_ADAPTER_NAME` takes precedence.
#![deny(clippy::all)]
pub use crate::builder::PixelsBuilder;
pub use crate::renderers::ScalingRenderer;
pub use raw_window_handle;
use raw_window_handle::HasRawWindowHandle;
use std::num::NonZeroU32;
use thiserror::Error;
pub use wgpu;
mod builder;
mod renderers;
/// A logical texture for a window surface.
#[derive(Debug)]
pub struct SurfaceTexture<'win, W: HasRawWindowHandle> {
window: &'win W,
size: SurfaceSize,
}
/// A logical texture size for a window surface.
#[derive(Debug)]
struct SurfaceSize {
width: u32,
height: u32,
}
/// Provides the internal state for custom shaders.
///
/// A reference to this struct is given to the `render_function` closure when using
/// [`Pixels::render_with`].
#[derive(Debug)]
pub struct PixelsContext {
/// The `Device` allows creating GPU resources.
pub device: wgpu::Device,
/// The `Queue` provides access to the GPU command queue.
pub queue: wgpu::Queue,
surface: wgpu::Surface,
/// This is the texture that your raw data is copied to by [`Pixels::render`] or
/// [`Pixels::render_with`].
pub texture: wgpu::Texture,
/// Provides access to the texture size.
pub texture_extent: wgpu::Extent3d,
pub texture_format: wgpu::TextureFormat,
/// Defines the "data rate" for the raw texture data. This is effectively the "bytes per pixel"
/// count.
///
/// Compressed textures may have less than one byte per pixel.
pub texture_format_size: f32,
/// A default renderer to scale the input texture to the screen size.
pub scaling_renderer: ScalingRenderer,
}
/// Represents a 2D pixel buffer with an explicit image resolution.
///
/// See [`PixelsBuilder`] for building a customized pixel buffer.
#[derive(Debug)]
pub struct Pixels {
context: PixelsContext,
surface_size: SurfaceSize,
present_mode: wgpu::PresentMode,
render_texture_format: wgpu::TextureFormat,
// Pixel buffer
pixels: Vec<u8>,
// The inverse of the scaling matrix used by the renderer
// Used to convert physical coordinates back to pixel coordinates (for the mouse)
scaling_matrix_inverse: ultraviolet::Mat4,
}
/// All the ways in which creating a pixel buffer can fail.
#[derive(Error, Debug)]
pub enum Error {
/// No suitable [`wgpu::Adapter`] found
#[error("No suitable `wgpu::Adapter` found.")]
AdapterNotFound,
/// Equivalent to [`wgpu::RequestDeviceError`]
#[error("No wgpu::Device found.")]
DeviceNotFound(wgpu::RequestDeviceError),
/// Equivalent to [`wgpu::SurfaceError`]
#[error("The GPU failed to acquire a surface frame.")]
Surface(wgpu::SurfaceError),
/// User-defined error from custom render function
#[error("User-defined error.")]
UserDefined(#[from] DynError),
}
type DynError = Box<dyn std::error::Error + Send + Sync + 'static>;
impl<'win, W: HasRawWindowHandle> SurfaceTexture<'win, W> {
/// Create a logical texture for a window surface.
///
/// It is recommended (but not required) that the `width` and `height` are equivalent to the
/// physical dimensions of the `surface`. E.g. scaled by the HiDPI factor.
///
/// # Examples
///
/// ```no_run
/// use pixels::SurfaceTexture;
/// use winit::event_loop::EventLoop;
/// use winit::window::Window;
///
/// let event_loop = EventLoop::new();
/// let window = Window::new(&event_loop).unwrap();
/// let size = window.inner_size();
///
/// let surface_texture = SurfaceTexture::new(size.width, size.height, &window);
/// # Ok::<(), pixels::Error>(())
/// ```
///
/// # Panics
///
/// Panics when `width` or `height` are 0.
pub fn new(width: u32, height: u32, window: &'win W) -> Self {
assert!(width > 0);
assert!(height > 0);
let size = SurfaceSize { width, height };
Self { window, size }
}
}
impl Pixels {
/// Create a pixel buffer instance with default options.
///
/// Any ratio differences between the pixel buffer texture size and surface texture size will
/// result in a border being added around the pixel buffer texture to maintain an integer
/// scaling ratio.
///
/// For instance, a pixel buffer with `320x240` can be scaled to a surface texture with sizes
/// `320x240`, `640x480`, `960x720`, etc. without adding a border because these are exactly
/// 1x, 2x, and 3x scales, respectively.
///
/// This method blocks the current thread, making it unusable on Web targets. Use
/// [`Pixels::new_async`] for a non-blocking alternative.
///
/// # Examples
///
/// ```no_run
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new(320, 240, surface_texture)?;
/// # Ok::<(), pixels::Error>(())
/// ```
///
/// # Errors
///
/// Returns an error when a [`wgpu::Adapter`] cannot be found.
///
/// # Panics
///
/// Panics when `width` or `height` are 0.
#[cfg(not(target_arch = "wasm32"))]
pub fn new<W: HasRawWindowHandle>(
width: u32,
height: u32,
surface_texture: SurfaceTexture<'_, W>,
) -> Result<Self, Error> {
PixelsBuilder::new(width, height, surface_texture).build()
}
/// Asynchronously create a pixel buffer instance with default options.
///
/// See [`Pixels::new`] for more information.
///
/// # Examples
///
/// ```no_run
/// # async fn test() -> Result<(), pixels::Error> {
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new_async(320, 240, surface_texture).await?;
/// # Ok::<(), pixels::Error>(())
/// # }
/// ```
///
/// # Errors
///
/// Returns an error when a [`wgpu::Adapter`] cannot be found.
///
/// # Panics
///
/// Panics when `width` or `height` are 0.
pub async fn new_async<W: HasRawWindowHandle>(
width: u32,
height: u32,
surface_texture: SurfaceTexture<'_, W>,
) -> Result<Self, Error> {
PixelsBuilder::new(width, height, surface_texture)
.build_async()
.await
}
/// Resize the pixel buffer and zero its contents.
///
/// This does not resize the surface upon which the pixel buffer texture is rendered. Use
/// [`Pixels::resize_surface`] to change the size of the surface texture.
///
/// The pixel buffer will be fit onto the surface texture as best as possible by scaling to the
/// nearest integer, e.g. 2x, 3x, 4x, etc. A border will be added around the pixel buffer
/// texture for non-integer scaling ratios.
///
/// Call this method to change the virtual screen resolution. E.g. when you want your pixel
/// buffer to be resized from `640x480` to `800x600`.
///
/// # Panics
///
/// Panics when `width` or `height` are 0.
pub fn resize_buffer(&mut self, width: u32, height: u32) {
assert!(width > 0);
assert!(height > 0);
// Recreate the backing texture
let (scaling_matrix_inverse, texture_extent, texture, scaling_renderer, pixels_buffer_size) =
builder::create_backing_texture(
&self.context.device,
// Backing texture values
width,
height,
self.context.texture_format,
// Render texture values
&self.surface_size,
self.render_texture_format,
);
self.scaling_matrix_inverse = scaling_matrix_inverse;
self.context.texture_extent = texture_extent;
self.context.texture = texture;
self.context.scaling_renderer = scaling_renderer;
// Resize the pixel buffer
self.pixels
.resize_with(pixels_buffer_size, Default::default);
}
/// Resize the surface upon which the pixel buffer texture is rendered.
///
/// This does not resize the pixel buffer. Use [`Pixels::resize_buffer`] to change the size of
/// the pixel buffer.
///
/// The pixel buffer texture will be fit onto the surface texture as best as possible by scaling
/// to the nearest integer, e.g. 2x, 3x, 4x, etc. A border will be added around the pixel buffer
/// texture for non-integer scaling ratios.
///
/// Call this method in response to a resize event from your window manager. The size expected
/// is in physical pixel units. Does nothing when `width` or `height` are 0.
pub fn resize_surface(&mut self, width: u32, height: u32) {
if width == 0 || height == 0 {
return;
}
// Update SurfaceTexture dimensions
self.surface_size.width = width;
self.surface_size.height = height;
// Update ScalingMatrix for mouse transformation
self.scaling_matrix_inverse = renderers::ScalingMatrix::new(
(
self.context.texture_extent.width as f32,
self.context.texture_extent.height as f32,
),
(width as f32, height as f32),
)
.transform
.inversed();
// Reconfigure the surface
self.reconfigure_surface();
// Update state for all render passes
self.context
.scaling_renderer
.resize(&self.context.queue, width, height);
}
/// Draw this pixel buffer to the configured [`SurfaceTexture`].
///
/// # Errors
///
/// Returns an error when [`wgpu::Surface::get_current_texture`] fails.
///
/// # Example
///
/// ```no_run
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new(320, 240, surface_texture)?;
///
/// // Clear the pixel buffer
/// let frame = pixels.get_frame();
/// for pixel in frame.chunks_exact_mut(4) {
/// pixel[0] = 0x00; // R
/// pixel[1] = 0x00; // G
/// pixel[2] = 0x00; // B
/// pixel[3] = 0xff; // A
/// }
///
/// // Draw it to the `SurfaceTexture`
/// pixels.render()?;
/// # Ok::<(), pixels::Error>(())
/// ```
pub fn render(&self) -> Result<(), Error> {
self.render_with(|encoder, render_target, context| {
context.scaling_renderer.render(encoder, render_target);
Ok(())
})
}
/// Draw this pixel buffer to the configured [`SurfaceTexture`] using a custom user-provided
/// render function.
///
/// Provides access to a [`wgpu::CommandEncoder`], a [`wgpu::TextureView`] from the surface
/// which you can use to render to the screen, and a [`PixelsContext`] with all of the internal
/// `wgpu` context.
///
/// The render function must return a `Result`. This allows fallible render functions to be
/// handled gracefully. The boxed `Error` will be made available in the [`Error::UserDefined`]
/// variant returned by `render_with()`.
///
/// # Errors
///
/// Returns an error when either [`wgpu::Surface::get_current_texture`] or the provided render
/// function fails.
///
/// # Example
///
/// ```no_run
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new(320, 240, surface_texture)?;
///
/// // Clear the pixel buffer
/// let frame = pixels.get_frame();
/// for pixel in frame.chunks_exact_mut(4) {
/// pixel[0] = 0x00; // R
/// pixel[1] = 0x00; // G
/// pixel[2] = 0x00; // B
/// pixel[3] = 0xff; // A
/// }
///
/// // Draw it to the `SurfaceTexture`
/// pixels.render_with(|encoder, render_target, context| {
/// context.scaling_renderer.render(encoder, render_target);
/// // etc...
/// Ok(())
/// })?;
/// # Ok::<(), pixels::Error>(())
/// ```
pub fn render_with<F>(&self, render_function: F) -> Result<(), Error>
where
F: FnOnce(
&mut wgpu::CommandEncoder,
&wgpu::TextureView,
&PixelsContext,
) -> Result<(), DynError>,
{
let frame = self
.context
.surface
.get_current_texture()
.or_else(|err| match err {
wgpu::SurfaceError::Outdated => {
// Reconfigure the surface to mitigate race condition on window resize.
// See https://github.com/parasyte/pixels/issues/121
self.reconfigure_surface();
self.context.surface.get_current_texture()
}
err => Err(err),
})
.map_err(Error::Surface)?;
let mut encoder =
self.context
.device
.create_command_encoder(&wgpu::CommandEncoderDescriptor {
label: Some("pixels_command_encoder"),
});
// Update the pixel buffer texture view
let bytes_per_row =
(self.context.texture_extent.width as f32 * self.context.texture_format_size) as u32;
self.context.queue.write_texture(
wgpu::ImageCopyTexture {
texture: &self.context.texture,
mip_level: 0,
origin: wgpu::Origin3d { x: 0, y: 0, z: 0 },
aspect: wgpu::TextureAspect::All,
},
&self.pixels,
wgpu::ImageDataLayout {
offset: 0,
bytes_per_row: NonZeroU32::new(bytes_per_row),
rows_per_image: NonZeroU32::new(self.context.texture_extent.height),
},
self.context.texture_extent,
);
let view = frame
.texture
.create_view(&wgpu::TextureViewDescriptor::default());
// Call the user's render function.
(render_function)(&mut encoder, &view, &self.context)?;
self.context.queue.submit(Some(encoder.finish()));
frame.present();
Ok(())
}
/// Reconfigure the surface.
///
/// Call this when the surface or presentation mode needs to be changed.
pub(crate) fn reconfigure_surface(&self) {
self.context.surface.configure(
&self.context.device,
&wgpu::SurfaceConfiguration {
usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
format: self.render_texture_format,
width: self.surface_size.width,
height: self.surface_size.height,
present_mode: self.present_mode,
},
);
}
/// Get a mutable byte slice for the pixel buffer. The buffer is _not_ cleared for you; it will
/// retain the previous frame's contents until you clear it yourself.
pub fn get_frame(&mut self) -> &mut [u8] {
&mut self.pixels
}
/// Calculate the pixel location from a physical location on the window,
/// dealing with window resizing, scaling, and margins. Takes a physical
/// position (x, y) within the window, and returns a pixel position (x, y).
///
/// The location must be given in physical units (for example, winit's `PhysicalLocation`)
///
/// If the given physical position is outside of the drawing area, this
/// function returns an `Err` value with the pixel coordinates outside of
/// the screen, using isize instead of usize.
///
/// ```no_run
/// use winit::dpi::PhysicalPosition;
///
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new(320, 240, surface_texture)?;
///
/// // A cursor position in physical units
/// let cursor_position: (f32, f32) = PhysicalPosition::new(0.0, 0.0).into();
///
/// // Convert it to a pixel location
/// let pixel_position: (usize, usize) = pixels.window_pos_to_pixel(cursor_position)
/// // Clamp the output to within the screen
/// .unwrap_or_else(|pos| pixels.clamp_pixel_pos(pos));
/// # Ok::<(), pixels::Error>(())
/// ```
pub fn window_pos_to_pixel(
&self,
physical_position: (f32, f32),
) -> Result<(usize, usize), (isize, isize)> {
let physical_width = self.surface_size.width as f32;
let physical_height = self.surface_size.height as f32;
let pixels_width = self.context.texture_extent.width as f32;
let pixels_height = self.context.texture_extent.height as f32;
let pos = ultraviolet::Vec4::new(
(physical_position.0 / physical_width - 0.5) * pixels_width,
(physical_position.1 / physical_height - 0.5) * pixels_height,
0.0,
1.0,
);
let pos = self.scaling_matrix_inverse * pos;
let offset_width = pixels_width.min(physical_width) / 2.0;
let offset_height = pixels_height.min(physical_height) / 2.0;
let pixel_x = (pos.x / pos.w + offset_width).floor() as isize;
let pixel_y = (-pos.y / pos.w + offset_height).floor() as isize;
if pixel_x < 0
|| pixel_x >= self.context.texture_extent.width as isize
|| pixel_y < 0
|| pixel_y >= self.context.texture_extent.height as isize
{
Err((pixel_x, pixel_y))
} else {
Ok((pixel_x as usize, pixel_y as usize))
}
}
/// Clamp a pixel position to the pixel buffer texture size.
///
/// This can be used to clamp the `Err` value returned by [`Pixels::window_pos_to_pixel`]
/// to a position clamped within the drawing area.
///
/// ```no_run
/// # use pixels::Pixels;
/// # let window = pixels_mocks::Rwh;
/// # let surface_texture = pixels::SurfaceTexture::new(320, 240, &window);
/// let mut pixels = Pixels::new(320, 240, surface_texture)?;
///
/// let pixel_pos = pixels.clamp_pixel_pos((-19, 20));
/// assert_eq!(pixel_pos, (0, 20));
///
/// let pixel_pos = pixels.clamp_pixel_pos((11, 3000));
/// assert_eq!(pixel_pos, (11, 239));
/// # Ok::<(), pixels::Error>(())
/// ```
pub fn clamp_pixel_pos(&self, pos: (isize, isize)) -> (usize, usize) {
(
pos.0
.max(0)
.min(self.context.texture_extent.width as isize - 1) as usize,
pos.1
.max(0)
.min(self.context.texture_extent.height as isize - 1) as usize,
)
}
/// Provides access to the internal [`wgpu::Device`].
pub fn device(&self) -> &wgpu::Device {
&self.context.device
}
/// Provides access to the internal [`wgpu::Queue`].
pub fn queue(&self) -> &wgpu::Queue {
&self.context.queue
}
/// Provides access to the internal source [`wgpu::Texture`].
///
/// This is the pre-scaled texture copied from the pixel buffer.
pub fn texture(&self) -> &wgpu::Texture {
&self.context.texture
}
/// Provides access to the internal [`PixelsContext`].
pub fn context(&self) -> &PixelsContext {
&self.context
}
/// Get the render texture format.
///
/// This texture format may be chosen automatically by the surface. See
/// [`PixelsBuilder::render_texture_format`] for more information.
pub fn render_texture_format(&self) -> wgpu::TextureFormat {
self.render_texture_format
}
}