vulkano_test/src/renderer/render_context.rs

use std::sync::Arc;
use vulkano::device::Device;
use vulkano::image::ImageUsage;
use vulkano::image::view::ImageView;
use vulkano::pipeline::graphics::viewport::Viewport;
use vulkano::swapchain::{Surface, Swapchain, SwapchainCreateInfo};
use vulkano::sync;
use vulkano::sync::GpuFuture;
use winit::window::Window;
use crate::renderer::window_size_dependent_setup;

pub struct RenderContext {
    pub(super) window: Arc<Window>,
    pub(super) swapchain: Arc<Swapchain>,
    pub(super) attachment_image_views: Vec<Arc<ImageView>>,
    pub(super) viewport: Viewport,
    pub(super) recreate_swapchain: bool,
    pub(super) previous_frame_end: Option<Box<dyn GpuFuture>>,
}

impl RenderContext {
    pub fn new(window: Arc<Window>, surface: Arc<Surface>, device: &Arc<Device>) -> Self {
        let window_size = window.inner_size();


        // 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 the swapchain.
        let (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 surface_capabilities = device
                .physical_device()
                .surface_capabilities(&surface, Default::default())
                .unwrap();

            // Choosing the internal format that the images will have.
            let (image_format, _) = device
                .physical_device()
                .surface_formats(&surface, Default::default())
                .unwrap()[0];

            // Please take a look at the docs for the meaning of the parameters we didn't mention.
            Swapchain::new(
                device.clone(),
                surface,
                SwapchainCreateInfo {
                    // Some drivers report an `min_image_count` of 1, but fullscreen mode requires
                    // at least 2. Therefore we must ensure the count is at least 2, otherwise the
                    // program would crash when entering fullscreen mode on those drivers.
                    min_image_count: surface_capabilities.min_image_count.max(2),

                    image_format,

                    // The size of the window, only used to initially setup the swapchain.
                    //
                    // NOTE:
                    // On some drivers the swapchain extent is specified by
                    // `surface_capabilities.current_extent` and the swapchain size must use this
                    // extent. This extent is always the same as the window size.
                    //
                    // However, other drivers don't specify a value, i.e.
                    // `surface_capabilities.current_extent` is `None`. These drivers will allow
                    // anything, but the only sensible value is the window size.
                    //
                    // Both of these cases need the swapchain to use the window size, so we just
                    // use that.
                    image_extent: window_size.into(),

                    image_usage: ImageUsage::COLOR_ATTACHMENT,

                    // 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.
                    composite_alpha: surface_capabilities
                        .supported_composite_alpha
                        .into_iter()
                        .next()
                        .unwrap(),

                    ..Default::default()
                },
            )
                .unwrap()
        };

        // When creating the swapchain, we only created plain images. To use them as an attachment
        // for rendering, we must wrap then in an image view.
        //
        // Since we need to draw to multiple images, we are going to create a different image view
        // for each image.
        let attachment_image_views = window_size_dependent_setup(&images);

        // Dynamic viewports allow us to recreate just the viewport when the window is resized.
        // Otherwise we would have to recreate the whole pipeline.
        let viewport = Viewport {
            offset: [0.0, 0.0],
            extent: window_size.into(),
            depth_range: 0.0..=1.0,
        };

        // 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 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 previous_frame_end = Some(sync::now(device.clone()).boxed());

        Self {
            window,
            swapchain,
            attachment_image_views,
            viewport,
            recreate_swapchain,
            previous_frame_end,
        }
    }
}