From 9a97c51262e49515681762b2165663c26a6babc2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Wed, 8 Dec 2021 16:06:21 +0100
Subject: [PATCH] Add a "placeholder" MeshPrimitive::Meshlets.

Just so I can create custom Trade::MeshData instances with meshlet
contents, nothing else.
---
 doc/changelog.dox                                  |  3 +++
 src/Magnum/GL/Mesh.cpp                             |  3 ++-
 src/Magnum/Implementation/meshPrimitiveMapping.hpp |  1 +
 src/Magnum/Mesh.h                                  | 12 +++++++++++-
 src/Magnum/Vk/MeshLayout.cpp                       |  3 ++-
 5 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/doc/changelog.dox b/doc/changelog.dox
index 26ca1c203..3a1bb8489 100644
--- a/doc/changelog.dox
+++ b/doc/changelog.dox
@@ -265,6 +265,9 @@ See also:
 
 @subsection changelog-latest-changes Changes and improvements
 
+-   Added @ref MeshPrimitive::Meshlets as a placeholder for future meshlet
+    support in @ref Trade::MeshData
+
 @subsubsection changelog-latest-changes-debugtools DebugTools library
 
 -   @ref DebugTools::CompareImage now supports comparing half-float pixel
diff --git a/src/Magnum/GL/Mesh.cpp b/src/Magnum/GL/Mesh.cpp
index 37a984488..ba20441c3 100644
--- a/src/Magnum/GL/Mesh.cpp
+++ b/src/Magnum/GL/Mesh.cpp
@@ -62,7 +62,8 @@ constexpr MeshPrimitive PrimitiveMapping[]{
     MeshPrimitive::TriangleFan,
     MeshPrimitive(~UnsignedInt{}), /* Instances */
     MeshPrimitive(~UnsignedInt{}), /* Faces */
-    MeshPrimitive(~UnsignedInt{})  /* Edges */
+    MeshPrimitive(~UnsignedInt{}), /* Edges */
+    MeshPrimitive(~UnsignedInt{})  /* Meshlets */
 };
 
 constexpr MeshIndexType IndexTypeMapping[]{
diff --git a/src/Magnum/Implementation/meshPrimitiveMapping.hpp b/src/Magnum/Implementation/meshPrimitiveMapping.hpp
index b16b8dd25..41b23033a 100644
--- a/src/Magnum/Implementation/meshPrimitiveMapping.hpp
+++ b/src/Magnum/Implementation/meshPrimitiveMapping.hpp
@@ -35,4 +35,5 @@ _c(TriangleFan)
 _c(Instances)
 _c(Faces)
 _c(Edges)
+_c(Meshlets)
 #endif
diff --git a/src/Magnum/Mesh.h b/src/Magnum/Mesh.h
index 5ef337e51..5f1c3ceff 100644
--- a/src/Magnum/Mesh.h
+++ b/src/Magnum/Mesh.h
@@ -183,7 +183,17 @@ enum class MeshPrimitive: UnsignedInt {
      * half-edge mesh representation.
      * @see @ref Trade::meshAttributeCustom()
      */
-    Edges
+    Edges,
+
+    /**
+     * Meshlet data.
+     * @m_since_latest
+     *
+     * Can be used to annotate @ref Trade::MeshData containing meshlet chunks,
+     * i.e. groups of vertex references together with per-meshlet culling
+     * information such as a bounding sphere or visibility cone.
+     */
+    Meshlets
 };
 
 /** @debugoperatorenum{MeshPrimitive} */
diff --git a/src/Magnum/Vk/MeshLayout.cpp b/src/Magnum/Vk/MeshLayout.cpp
index ac485c340..3b32ef298 100644
--- a/src/Magnum/Vk/MeshLayout.cpp
+++ b/src/Magnum/Vk/MeshLayout.cpp
@@ -45,7 +45,8 @@ constexpr MeshPrimitive MeshPrimitiveMapping[]{
     MeshPrimitive::TriangleFan,
     MeshPrimitive(~Int{}), /* Instances */
     MeshPrimitive(~Int{}), /* Faces */
-    MeshPrimitive(~Int{})  /* Edges */
+    MeshPrimitive(~Int{}), /* Edges */
+    MeshPrimitive(~Int{})  /* Meshlets */
 };
 
 }