From 594c736afa0582a65d4dfc2ad7749687a9c57094 Mon Sep 17 00:00:00 2001
From: Sergey Kosarevsky <sk@linderdaum.com>
Date: Wed, 11 Dec 2024 00:24:11 -0800
Subject: [PATCH] Fixed skybox push constants size to be less than 128 bytes

---
 Chapter08/02_SceneGraph/src/skybox.frag | 3 +--
 Chapter08/02_SceneGraph/src/skybox.vert | 5 ++---
 Chapter08/03_LargeScene/src/main.cpp    | 6 ++----
 Chapter10/Skybox.h                      | 6 ++----
 4 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/Chapter08/02_SceneGraph/src/skybox.frag b/Chapter08/02_SceneGraph/src/skybox.frag
index db52cf9..ed8031b 100644
--- a/Chapter08/02_SceneGraph/src/skybox.frag
+++ b/Chapter08/02_SceneGraph/src/skybox.frag
@@ -1,8 +1,7 @@
 //
 
 layout(push_constant) uniform PerFrameData {
-  mat4 view;
-  mat4 proj;
+  mat4 mvp;
   uint texSkybox;
 } pc;
 
diff --git a/Chapter08/02_SceneGraph/src/skybox.vert b/Chapter08/02_SceneGraph/src/skybox.vert
index 90452da..b2df36c 100644
--- a/Chapter08/02_SceneGraph/src/skybox.vert
+++ b/Chapter08/02_SceneGraph/src/skybox.vert
@@ -1,8 +1,7 @@
 //
 
 layout(push_constant) uniform PerFrameData {
-  mat4 view;
-  mat4 proj;
+  mat4 mvp;
   uint texSkybox;
 } pc;
 
@@ -31,6 +30,6 @@ const int indices[36] = int[36](
 
 void main() {
 	int idx = indices[gl_VertexIndex];
-	gl_Position = pc.proj * mat4(mat3(pc.view)) * vec4(1.0 * pos[idx], 1.0);
+	gl_Position = pc.mvp * vec4(1.0 * pos[idx], 1.0);
 	dir = pos[idx].xyz;
 }
diff --git a/Chapter08/03_LargeScene/src/main.cpp b/Chapter08/03_LargeScene/src/main.cpp
index c49e409..450c492 100644
--- a/Chapter08/03_LargeScene/src/main.cpp
+++ b/Chapter08/03_LargeScene/src/main.cpp
@@ -176,12 +176,10 @@ int main()
         buf.cmdPushDebugGroupLabel("Skybox", 0xff0000ff);
         buf.cmdBindRenderPipeline(pipelineSkybox);
         const struct {
-          mat4 view;
-          mat4 proj;
+          mat4 mvp;
           uint32_t texSkybox;
         } pc = {
-          .view      = view,
-          .proj      = proj,
+          .mvp       = proj * mat4(mat3(view)), // discard the translation
           .texSkybox = texSkybox.index(),
         };
         buf.cmdPushConstants(pc);
diff --git a/Chapter10/Skybox.h b/Chapter10/Skybox.h
index eacd7f3..a27b499 100644
--- a/Chapter10/Skybox.h
+++ b/Chapter10/Skybox.h
@@ -26,12 +26,10 @@ class Skybox
     buf.cmdPushDebugGroupLabel("Skybox", 0xff0000ff);
     buf.cmdBindRenderPipeline(pipelineSkybox);
     const struct {
-      mat4 view;
-      mat4 proj;
+      mat4 mvp;
       uint32_t texSkybox;
     } pc = {
-      .view      = view,
-      .proj      = proj,
+      .mvp       = proj * mat4(mat3(view)), // discard the translation
       .texSkybox = texSkybox.index(),
     };
     buf.cmdPushConstants(pc);