From fc940721e68f7b8a39f63afd008954b253b3f133 Mon Sep 17 00:00:00 2001
From: Squareys <squareys@googlemail.com>
Date: Sun, 3 May 2020 10:23:05 +0200
Subject: [PATCH] Shaders: Add Weights and JointIndices attribute types

Signed-off-by: Squareys <squareys@googlemail.com>
---
 src/Magnum/Shaders/Generic.h | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/Magnum/Shaders/Generic.h b/src/Magnum/Shaders/Generic.h
index 43858c0cd..4544dcfda 100644
--- a/src/Magnum/Shaders/Generic.h
+++ b/src/Magnum/Shaders/Generic.h
@@ -126,13 +126,13 @@ both bitangents and object ID for instancing, \n
 <tr>
 <td>6</td>
 <td colspan="3">
-* *Reserved* --- vertex weights
+@ref Weights
 </td>
 </tr>
 <tr>
 <td>7</td>
 <td colspan="3">
-* *Reserved* --- bone indices
+@ref JointIndices
 </td>
 </tr>
 <tr>
@@ -150,13 +150,13 @@ both bitangents and object ID for instancing, \n
 <tr>
 <td>10</td>
 <td colspan="2">
-* *Reserved* --- 2nd vertex weights
+@ref Weights
 </td>
 </tr>
 <tr>
 <td>11</td>
 <td colspan="2">
-* *Reserved* --- 2nd bone indices
+@ref JointIndices
 </td>
 </tr>
 <tr>
@@ -358,7 +358,26 @@ template<UnsignedInt dimensions> struct Generic {
      */
     typedef GL::Attribute<5, Vector3> Normal;
 
-    /* 6, 7 reserved for vertex weights / bone IDs */
+    /**
+     * @brief Skin weights
+     *
+     * @ref Magnum::Vector4 "Vector4", four weights of influence per @ref JointIndices.
+     * Corresponds to @ref Trade::MeshAttribute::Weights.
+     */
+    // TODO: E.g. gltf supports importing multiple sets of 4 weights (WEIGHTS_0 [0;3], WEIGHTS_1 [4;7])
+    // I suppose these would require special shaders and it's fine to only support 4 for the GenericShaders
+    typedef GL::Attribute<6, Vector4> Weights;
+
+    /**
+     * @brief Joint indices
+     *
+     * @ref Magnum::Vector4 "Vector4", four weights of influence per @ref JointIndices.
+     * Corresponds to @ref Trade::MeshAttribute::Weights.
+     */
+    // TODO: E.g. gltf supports importing multiple sets of 4 indices (JOINTS_0 [0;3], JOINTS_1 [4;7])
+    // I suppose these would require special shaders and it's fine to only support 4 for the GenericShaders
+    // TODO: This is called "Joints" in gltf.
+    typedef GL::Attribute<7, Vector4> JointIndices;
 
     /**
      * @brief (Instanced) transformation matrix