From 0bcc87adc33970de359257fc428e4acc0b24bb9f Mon Sep 17 00:00:00 2001
From: David Allemang <david.allemang@kitware.com>
Date: Mon, 1 Apr 2024 23:49:26 -0400
Subject: [PATCH] frames in flight

---
 src/main.zig | 66 ++++++++++++++++++++++++----------------------------
 1 file changed, 31 insertions(+), 35 deletions(-)

diff --git a/src/main.zig b/src/main.zig
index 8fceabd..5a5accf 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -107,25 +107,18 @@ pub fn main() !void {
         image: vk.Image = .null_handle,
         view: vk.ImageView = .null_handle,
         cmdbuf: vk.CommandBuffer = .null_handle,
-        // fence: vk.Fence = .null_handle,
-        // image_available: vk.Semaphore = .null_handle,
-        // render_finished: vk.Semaphore = .null_handle,
+        fence: vk.Fence = .null_handle,
+        image_available: vk.Semaphore = .null_handle,
+        render_finished: vk.Semaphore = .null_handle,
     };
 
     var chain = std.MultiArrayList(ChainImage){};
     defer chain.deinit(ally);
     defer vkd.freeCommandBuffers(dev, pool, @intCast(chain.len), chain.items(.cmdbuf).ptr);
     defer for (chain.items(.view)) |view| vkd.destroyImageView(dev, view, null);
-    // defer for (chain.items(.fence)) |fence| vkd.destroyFence(dev, fence, null);
-    // defer for (chain.items(.image_available)) |sem| vkd.destroySemaphore(dev, sem, null);
-    // defer for (chain.items(.render_finished)) |sem| vkd.destroySemaphore(dev, sem, null);
-
-    const frame_fence = try vkd.createFence(dev, &.{ .flags = .{ .signaled_bit = true } }, null);
-    defer vkd.destroyFence(dev, frame_fence, null);
-    const image_available = try vkd.createSemaphore(dev, &.{}, null);
-    defer vkd.destroySemaphore(dev, image_available, null);
-    const render_finished = try vkd.createSemaphore(dev, &.{}, null);
-    defer vkd.destroySemaphore(dev, render_finished, null);
+    defer for (chain.items(.fence)) |fence| vkd.destroyFence(dev, fence, null);
+    defer for (chain.items(.image_available)) |sem| vkd.destroySemaphore(dev, sem, null);
+    defer for (chain.items(.render_finished)) |sem| vkd.destroySemaphore(dev, sem, null);
 
     swapchain = try vkd.createSwapchainKHR(dev, &.{
         .surface = surface,
@@ -164,17 +157,17 @@ pub fn main() !void {
         }, null);
     }
 
-    // for (chain.items(.fence)) |*fence| {
-    //     fence.* = try vkd.createFence(dev, &.{ .flags = .{ .signaled_bit = true } }, null);
-    // }
-    //
-    // for (chain.items(.image_available)) |*sem| {
-    //     sem.* = try vkd.createSemaphore(dev, &.{}, null);
-    // }
-    //
-    // for (chain.items(.render_finished)) |*sem| {
-    //     sem.* = try vkd.createSemaphore(dev, &.{}, null);
-    // }
+    for (chain.items(.fence)) |*fence| {
+        fence.* = try vkd.createFence(dev, &.{ .flags = .{ .signaled_bit = true } }, null);
+    }
+
+    for (chain.items(.image_available)) |*sem| {
+        sem.* = try vkd.createSemaphore(dev, &.{}, null);
+    }
+
+    for (chain.items(.render_finished)) |*sem| {
+        sem.* = try vkd.createSemaphore(dev, &.{}, null);
+    }
 
     try vkd.allocateCommandBuffers(dev, &.{
         .command_buffer_count = @intCast(chain.len),
@@ -224,7 +217,7 @@ pub fn main() !void {
         try record_cmdbuf(cmdbuf, vkd, image, view, extent, pipeline, vertex_buffer, index_buffer);
     }
 
-    // var index: u32 = 0;
+    var index: u32 = 0;
 
     while (c.glfwWindowShouldClose(window) == c.GLFW_FALSE) {
         var w: c_int = undefined;
@@ -237,31 +230,32 @@ pub fn main() !void {
             continue;
         }
 
-        _ = try vkd.waitForFences(dev, 1, @ptrCast(&frame_fence), vk.TRUE, std.math.maxInt(u64));
-        try vkd.resetFences(dev, 1, @ptrCast(&frame_fence));
+        const frame: ChainImage = chain.get(index);
+        // const next_frame: ChainImage = chain.get((index + 1) % chain.len);
 
-        // const frame: ChainImage = chain.get();
+        _ = try vkd.waitForFences(dev, 1, @ptrCast(&frame.fence), vk.TRUE, std.math.maxInt(u64));
+        try vkd.resetFences(dev, 1, @ptrCast(&frame.fence));
 
         // var index: u32 = undefined;
         // try vkd.acquireNextImageKHR(dev, swapchain, std.math.maxInt(u64), frame., fence);
-        const result = try vkd.acquireNextImageKHR(dev, swapchain, std.math.maxInt(u64), image_available, .null_handle);
-        
+        const result = try vkd.acquireNextImageKHR(dev, swapchain, std.math.maxInt(u64), frame.image_available, .null_handle);
+
         // std.log.debug("frame {d}", .{result.image_index});
-        const frame = chain.get(result.image_index);
+        // const frame = chain.get(result.image_index);
 
         try vkd.queueSubmit(queue, 1, @ptrCast(&vk.SubmitInfo{
             .wait_semaphore_count = 1,
-            .p_wait_semaphores = @ptrCast(&image_available),
+            .p_wait_semaphores = @ptrCast(&frame.image_available),
             .p_wait_dst_stage_mask = @ptrCast(&vk.PipelineStageFlags{ .color_attachment_output_bit = true }),
             .command_buffer_count = 1,
             .p_command_buffers = @ptrCast(&frame.cmdbuf),
             .signal_semaphore_count = 1,
-            .p_signal_semaphores = @ptrCast(&render_finished),
-        }), frame_fence);
+            .p_signal_semaphores = @ptrCast(&frame.render_finished),
+        }), frame.fence);
 
         _ = try vkd.queuePresentKHR(queue, &.{
             .wait_semaphore_count = 1,
-            .p_wait_semaphores = @ptrCast(&render_finished),
+            .p_wait_semaphores = @ptrCast(&frame.render_finished),
             .swapchain_count = 1,
             .p_swapchains = @ptrCast(&swapchain),
             .p_image_indices = @ptrCast(&result.image_index),
@@ -294,6 +288,8 @@ pub fn main() !void {
         // }
 
         c.glfwPollEvents();
+
+        index = @intCast((index + 1) % chain.len);
     }
 
     // try swapchain.waitForAllFences();