Multi thread example

Author: lwjglgamedev

bookcontents/README.md

@@ -22,5 +22,7 @@ The book is structured in the following chapters:
 - [Chapter 17](chapter-17/chapter-17.md): Animations.
 - [Chapter 18](chapter-18/chapter-18.md): Buffer Device Address (BDA).
 - [Chapter 18](chapter-19/chapter-19.md): Indirect drawing.
+- [Chapter 18](chapter-19/chapter-20.md): Multi-thread.
+- [Chapter 18](chapter-19/chapter-21.md): Ray tracing.
 - [Appendix 01](appendix-01/appendix-01.md): This chapter provides some insights on how to troubleshoot a loss of device error.
 - [Appendix 02](appendix-02/appendix-02.md): This chapter provides a simple 3D game to put everything together

bookcontents/chapter-07/chapter-07.md

@@ -919,7 +919,7 @@ public class ScnRender {
                     .imageView(depthAttachments[i].getImageView().getVkImageView())
                     .imageLayout(VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL)
                     .loadOp(VK_ATTACHMENT_LOAD_OP_CLEAR)
-                    .storeOp(VK_ATTACHMENT_STORE_OP_STORE)
+                    .storeOp(VK_ATTACHMENT_STORE_OP_DONT_CARE)
                     .clearValue(clearValue);
             result[i] = attachments;
         }
@@ -929,7 +929,9 @@ public class ScnRender {
 }
 ```
 
-The code is quite similar as the one used for color attachments, but the layout is different: `VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL` to state that is for depth values.
+The code is quite similar as the one used for color attachments, but the layout is different: `VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL` to state that is for depth values. In this case the store operation can be
+`VK_ATTACHMENT_STORE_OP_DONT_CARE` instead of `VK_ATTACHMENT_STORE_OP_STORE` because we do not need to store the results, we just
+need a depth attachment to perform depth tests. We do not need to access those results later on.
 
 The `createPipeline` needs to be updated to set the push constants range:
 

bookcontents/chapter-11/chapter-11.md

@@ -140,7 +140,7 @@ public class ScnRender {
 ```
 
 In addition to just having a single `VkRenderingAttachmentInfo.Buffer`, the `imageLayout` is now `VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL` instead of being
-`VK_IMAGE_LAYOUT_ATTACHMENT_OPTIMAL_KHR` since the image is not related yo the swp chain now. The methods `createDepthAttachment` and `createDepthAttachmentInfo` are
+`VK_IMAGE_LAYOUT_ATTACHMENT_OPTIMAL_KHR` since the image is not related yo the swap chain now. The methods `createDepthAttachment` and `createDepthAttachmentInfo` are
 like this:
 
 ```java
@@ -159,7 +159,7 @@ public class ScnRender {
                 .imageView(depthAttachment.getImageView().getVkImageView())
                 .imageLayout(VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL)
                 .loadOp(VK_ATTACHMENT_LOAD_OP_CLEAR)
-                .storeOp(VK_ATTACHMENT_STORE_OP_STORE)
+                .storeOp(VK_ATTACHMENT_STORE_OP_DONT_CARE)
                 .clearValue(clearValue);
     }
     ...

bookcontents/chapter-14/chapter-14.md

@@ -183,7 +183,7 @@ public class ScnRender {
                 .imageView(mrtAttachments.getDepthAttachment().getImageView().getVkImageView())
                 .imageLayout(VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL)
                 .loadOp(VK_ATTACHMENT_LOAD_OP_CLEAR)
-                .storeOp(VK_ATTACHMENT_STORE_OP_STORE)
+                .storeOp(VK_ATTACHMENT_STORE_OP_DONT_CARE)
                 .clearValue(clearValue);
     }
 
@@ -272,12 +272,6 @@ public class ScnRender {
                         VK_ACCESS_NONE, VK_ACCESS_2_COLOR_ATTACHMENT_WRITE_BIT,
                         VK_IMAGE_ASPECT_COLOR_BIT);
             }
-            VkUtils.imageBarrier(stack, cmdHandle, mrtAttachments.getDepthAttachment().getImage().getVkImage(),
-                    VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
-                    VK_PIPELINE_STAGE_2_EARLY_FRAGMENT_TESTS_BIT | VK_PIPELINE_STAGE_2_LATE_FRAGMENT_TESTS_BIT,
-                    VK_PIPELINE_STAGE_2_EARLY_FRAGMENT_TESTS_BIT | VK_PIPELINE_STAGE_2_LATE_FRAGMENT_TESTS_BIT,
-                    VK_ACCESS_2_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT, VK_ACCESS_2_DEPTH_STENCIL_ATTACHMENT_READ_BIT | VK_ACCESS_2_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT,
-                    VK_IMAGE_ASPECT_DEPTH_BIT);
             ...
             int width = mrtAttachments.getWidth();
             int height = mrtAttachments.getHeight();

bookcontents/chapter-16/chapter-16.md

@@ -478,10 +478,7 @@ public class ShadowRender {
 }
 ```
 
-We create the depth attachment in the `createDepthAttachment` information. In this case it will be a single image but with as many layers as cascade shadows will be. We
-will see how this modifies the creation of attachments. The size of the depth image will not be dependant on the screen size, it weill be a configurable value.
-The rest of the methods to crate attachment information, render information and shader and pipeline are quite similar.
-In this case, we are using three shader modules for vertex, geometry and fragment shading.
+We create the depth attachment in the `createDepthAttachment` information. In this case it will be a single image but with as many layers as cascade shadows will be. We will see how this modifies the creation of attachments. The size of the depth image will not be dependant on the screen size, it weill be a configurable value. The rest of the methods to crate attachment information, render information and shader and pipeline are quite similar. In this case, we are using three shader modules for vertex, geometry and fragment shading. In this case, we need to store depth attachment, this is why we use the `VK_ATTACHMENT_STORE_OP_STORE`, because we will sample it while applying lights
 
 The `ShadowRender` class defines also a `cleanup` method to free the resources and some getters to retrieve the depth attachment and the cascade shadows.
 

bookcontents/chapter-20/chapter-20.md

@@ -1,2 +1,2 @@
-# Chapter 20 - Ray tracing
+# Chapter 20 - Multi-thread
 TBD

bookcontents/chapter-21/chapter-21.md

@@ -0,0 +1,2 @@
+# Chapter 20 - Ray Tracing
+TBD

bookcontents/pandoc/settings.yaml

@@ -22,6 +22,7 @@ input-files:
   - ./chapter-18/chapter-18.md
   - ./chapter-19/chapter-19.md
   - ./chapter-20/chapter-20.md
+  - ./chapter-21/chapter-21.md
   - ./appendix-01/appendix-01.md
   - ./appendix-02/appendix-02.md
 epub-cover-image: pandoc/cover.png
@@ -50,6 +51,7 @@ resource-path:
   - chapter-18
   - chapter-19
   - chapter-20
+  - chapter-21
   - appendix-01
   - appendix-02
 toc: true

bookcontents/vulkanbook.epub

@@ -1,15 +1,24 @@
 package org.vulkanb.eng;
 
 import org.vulkanb.eng.graph.Render;
+import org.vulkanb.eng.graph.vk.VkUtils;
 import org.vulkanb.eng.scene.Scene;
 import org.vulkanb.eng.sound.SoundManager;
 import org.vulkanb.eng.wnd.Window;
 
+import java.util.concurrent.*;
+
 public class Engine {
 
+    private static final int WORKER_COUNT = 2;
     private final EngCtx engCtx;
+    private final ExecutorService executor;
     private final IGameLogic gameLogic;
+    private final Phaser phaser = new Phaser(1);
     private final Render render;
+    private final Callable<Void> renderTask;
+    private int currentRenderFrame;
+    private int currentUpdateFrame;
 
     public Engine(String windowTitle, IGameLogic appLogic) {
         this.gameLogic = appLogic;
@@ -18,9 +27,18 @@ public Engine(String windowTitle, IGameLogic appLogic) {
         render = new Render(engCtx);
         InitData initData = gameLogic.init(engCtx);
         render.init(engCtx, initData);
+        executor = Executors.newFixedThreadPool(WORKER_COUNT);
+        renderTask = () -> {
+            render.render(engCtx, currentUpdateFrame);
+            phaser.arriveAndDeregister();
+            return null;
+        };
+        currentUpdateFrame = 1;
+        currentRenderFrame = 0;
     }
 
     private void cleanup() {
+        executor.shutdownNow();
         gameLogic.cleanup();
         render.cleanup();
         engCtx.cleanup();
@@ -34,10 +52,16 @@ public void run() {
 
         long updateTime = initialTime;
         Window window = engCtx.window();
+        boolean firstExec = true;
         while (!window.shouldClose()) {
             long now = System.currentTimeMillis();
             deltaUpdate += (now - initialTime) / timeU;
 
+            if (!firstExec) {
+                phaser.register();
+                executor.submit(renderTask);
+            }
+
             window.pollEvents();
             gameLogic.input(engCtx, now - initialTime);
             window.resetInput();
@@ -48,10 +72,17 @@ public void run() {
                 updateTime = now;
                 deltaUpdate--;
             }
+            render.updateGlobalBuffers(engCtx, currentUpdateFrame);
+
+            if (!firstExec) {
+                phaser.arriveAndAwaitAdvance();
+            }
 
-            render.render(engCtx);
+            currentUpdateFrame = (currentUpdateFrame + 1) % VkUtils.MAX_IN_FLIGHT;
+            currentRenderFrame = (currentRenderFrame + 1) % VkUtils.MAX_IN_FLIGHT;
 
             initialTime = now;
+            firstExec = false;
         }
 
         cleanup();