zig-experiments/src/au/SwapChain.zig

const std = @import("std");
const au = @import("../au.zig");
const vk = @import("vk");

const Self = @This();

alloc: std.mem.Allocator,
cinfo: vk.SwapchainCreateInfoKHR,
handle: vk.SwapchainKHR = .null_handle,
images: std.ArrayListUnmanaged(vk.Image) = .{},
views: std.ArrayListUnmanaged(vk.ImageView) = .{},

pub fn init(alloc: std.mem.Allocator) !Self {
    const caps = try au.I.getPhysicalDeviceSurfaceCapabilitiesKHR(au.device_config.pdev, au.W.surface);

    var min_image_count = @max(3, caps.min_image_count + 1); // todo magic numbers
    if (caps.max_image_count > 0) {
        min_image_count = @min(min_image_count, caps.max_image_count);
    }

    // determine format
    const format = au.device_config.format;

    return .{
        .alloc = alloc,
        .cinfo = .{
            .surface = au.W.surface,
            .min_image_count = min_image_count,
            .image_format = format.format,
            .image_color_space = format.color_space,
            .image_extent = undefined, // set in rebuild
            .image_array_layers = 1,
            .image_usage = .{ .color_attachment_bit = true },
            .image_sharing_mode = .exclusive,
            .pre_transform = .{ .identity_bit_khr = true },
            .composite_alpha = .{ .opaque_bit_khr = true },
            .present_mode = au.device_config.mode,
            .clipped = vk.TRUE,
            .old_swapchain = .null_handle,
        },
    };
}

pub fn deinit(self: *Self) void {
    for (self.views.items) |view| {
        au.D.destroyImageView(view, null);
    }
    self.views.deinit(self.alloc);

    self.images.deinit(self.alloc);

    au.D.destroySwapchainKHR(self.handle, null);
}

/// mark that the swapchain _should_ be rebuilt with the given extent
/// this function is reentrant, so the swapchain can be marked multiple times
/// and only one rebuild occur
pub fn mark(self: *Self) void {
    self.handle = .null_handle;
}

/// rebuild the swapchain only if it is marked. return true if the swapchain was rebuilt.
pub fn rebuild(self: *Self) !bool {
    if (self.handle != .null_handle) return false;

    const caps = try au.I.getPhysicalDeviceSurfaceCapabilitiesKHR(au.device_config.pdev, self.cinfo.surface);
    self.cinfo.image_extent = caps.current_extent;

    self.handle = try au.D.createSwapchainKHR(&self.cinfo, null);
    au.D.destroySwapchainKHR(self.cinfo.old_swapchain, null);
    self.cinfo.old_swapchain = self.handle;

    var count: u32 = undefined;
    _ = try au.D.getSwapchainImagesKHR(self.handle, &count, null);
    try self.images.resize(self.alloc, count);
    _ = try au.D.getSwapchainImagesKHR(self.handle, &count, self.images.items.ptr);

    for (self.views.items) |view| {
        au.D.destroyImageView(view, null);
    }
    try self.views.resize(self.alloc, count);
    for (self.images.items, self.views.items) |image, *view| {
        view.* = try au.D.createImageView(&vk.ImageViewCreateInfo{ .image = image, .view_type = .@"2d", .format = self.cinfo.image_format, .components = .{ .r = .identity, .g = .identity, .b = .identity, .a = .identity }, .subresource_range = .{
            .aspect_mask = .{ .color_bit = true },
            .base_mip_level = 0,
            .level_count = 1,
            .base_array_layer = 0,
            .layer_count = 1,
        } }, null);
    }

    return true;
}

pub fn acquire(self: Self, semaphore: vk.Semaphore, fence: vk.Fence) !Target {
    const acq = try au.D.acquireNextImageKHR(self.handle, std.math.maxInt(u64), semaphore, fence);
    return .{
        .idx = acq.image_index,
        .image = self.images.items[acq.image_index],
        .view = self.views.items[acq.image_index],
    };
}

const Target = struct {
    idx: u32,
    image: vk.Image,
    view: vk.ImageView,

    pub fn begin_rendering(self: Target, cmd: au.CommandBufferProxy, area: vk.Rect2D) void {
        cmd.pipelineBarrier(
            .{ .top_of_pipe_bit = true },
            .{ .color_attachment_output_bit = true },
            .{},
            0,
            null,
            0,
            null,
            1,
            &.{
                vk.ImageMemoryBarrier{
                    .src_access_mask = .{},
                    .dst_access_mask = .{ .color_attachment_write_bit = true },
                    .old_layout = .undefined,
                    .new_layout = .color_attachment_optimal,
                    .src_queue_family_index = 0,
                    .dst_queue_family_index = 0,
                    .image = self.image,
                    .subresource_range = .{
                        .aspect_mask = .{ .color_bit = true },
                        .base_mip_level = 0,
                        .level_count = 1,
                        .base_array_layer = 0,
                        .layer_count = 1,
                    },
                },
            },
        );

        cmd.beginRendering(&vk.RenderingInfo{
            .render_area = area,
            .layer_count = 1,
            .view_mask = 0,
            .color_attachment_count = 1,
            .p_color_attachments = &.{
                vk.RenderingAttachmentInfo{
                    .image_view = self.view,
                    .image_layout = .color_attachment_optimal,
                    .resolve_mode = .{},
                    .resolve_image_view = .null_handle,
                    .resolve_image_layout = .undefined,
                    .load_op = .clear,
                    .store_op = .store,
                    .clear_value = .{ .color = .{ .float_32 = .{ 0, 0, 0, 1 } } },
                },
            },
        });
    }

    pub fn end_rendering(self: Target, cmd: au.CommandBufferProxy) void {
        cmd.endRendering();

        cmd.pipelineBarrier(
            .{ .color_attachment_output_bit = true },
            .{ .bottom_of_pipe_bit = true },
            .{},
            0,
            null,
            0,
            null,
            1,
            &.{
                vk.ImageMemoryBarrier{
                    .src_access_mask = .{ .color_attachment_write_bit = true },
                    .dst_access_mask = .{},
                    .old_layout = .color_attachment_optimal,
                    .new_layout = .present_src_khr,
                    .src_queue_family_index = 0,
                    .dst_queue_family_index = 0,
                    .image = self.image,
                    .subresource_range = .{
                        .aspect_mask = .{ .color_bit = true },
                        .base_mip_level = 0,
                        .level_count = 1,
                        .base_array_layer = 0,
                        .layer_count = 1,
                    },
                },
            },
        );
    }
};

pub fn present(self: Self, wait_semaphores: []const vk.Semaphore, target: Target) !vk.Result {
    return try au.Q.presentKHR(&vk.PresentInfoKHR{
        .wait_semaphore_count = @intCast(wait_semaphores.len),
        .p_wait_semaphores = wait_semaphores.ptr,
        .swapchain_count = 1,
        .p_swapchains = &.{self.handle},
        .p_image_indices = &.{target.idx},
        .p_results = null,
    });
}