From 9111df625733fa76fd4b1924c56d16018d1d6ef9 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Sat, 3 Jan 2026 16:21:14 -0600
Subject: [PATCH] add weight and joint accessors

---
 gltf.hpp      | 61 +++++++++++++++++++++++++++++----------------------
 render_cpp.py | 23 ++++++++++++++-----
 2 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/gltf.hpp b/gltf.hpp
index 646b879..5eb089e 100644
--- a/gltf.hpp
+++ b/gltf.hpp
@@ -1,29 +1,37 @@
-template <typename T>
-struct Array {
-  T * e;
-  int length;
-};
-
 struct Mesh {
-  D3DXVECTOR3 * position;
-  D3DXVECTOR3 * normal;
-  D3DXVECTOR2 * texcoord_0;
-  DWORD * indices;
+  const D3DXVECTOR3 * position;
+  const DWORD position_size;
+
+  const D3DXVECTOR3 * normal;
+  const DWORD normal_size;
+
+  const D3DXVECTOR2 * texcoord_0;
+  const DWORD texcoord_0_size;
+
+  const D3DXVECTOR4 * weights_0;
+  const DWORD weights_0_size;
+
+  const D3DXVECTOR4 * joints_0;
+  const DWORD joints_0_size;
+
+  const DWORD * indices;
+  const DWORD indices_size;
 };
 
 struct Skin;
 
 struct Node {
-  Skin * skin; // skin index (global)
-  Mesh * mesh; // mesh index (global)
-  D3DXVECTOR3 scale;
-  D3DXVECTOR3 translation;
-  D3DXQUATERNION rotation;
+  const Skin * skin; // skin index (global)
+  const Mesh * mesh; // mesh index (global)
+  const D3DXVECTOR3 translation;
+  const D3DXQUATERNION rotation;
+  const D3DXVECTOR3 scale;
 };
 
 struct Skin {
-  D3DXMATRIX * inverse_bind_matrices; // accessor
-  Array<Node *> joints;
+  const D3DXMATRIX * inverse_bind_matrices; // accessor
+  const Node ** joints;
+  DWORD joints_length;
 };
 
 enum AnimationChannelPath {
@@ -34,19 +42,20 @@ enum AnimationChannelPath {
 };
 
 struct AnimationSampler {
-  float * input;  // accessor index, containing keyframe timestamps
-  void * output; // accessor index, containing keyframe values (type depends on channel target path)
+  const float * input;  // accessor index, containing keyframe timestamps
+  const void * output; // accessor index, containing keyframe values (type depends on channel target path)
+  const int length;
 };
 
 struct AnimationChannel {
-  AnimationSampler * sampler; // sampler index, this animation
+  const AnimationSampler * sampler; // sampler index, this animation
   struct {
-    Node * node; // node index
-    AnimationChannelPath path; // property to animate
+    const Node * node; // node index
+    const AnimationChannelPath path; // property to animate
   } target;
 };
 
-struct Animation {
-  Array<AnimationChannel> channels;
-  Array<AnimationSampler> samplers;
-};
+//struct Animation {
+//  const AnimationChannel * channels;
+//  const AnimationSampler * samplers;
+//};
diff --git a/render_cpp.py b/render_cpp.py
index 2780889..a1561eb 100644
--- a/render_cpp.py
+++ b/render_cpp.py
@@ -75,12 +75,23 @@ def render_meshes(gltf):
         position = attributes["POSITION"]
         normal = attributes.get("NORMAL", None)
         texcoord_0 = attributes.get("TEXCOORD_0", None)
+        weights_0 = attributes.get("WEIGHTS_0", None)
+        joints_0 = attributes.get("JOINTS_0", None)
         indices = primitive["indices"]
         yield f"const Mesh mesh_{mesh_ix} = {{"
         yield f"accessor_{position}, // position"
-        yield f"accessor_{normal}, // normal" if normal is not None else "NULL,"
-        yield f"accessor_{texcoord_0}, // texcoord_0" if texcoord_0 is not None else "NULL,"
+        yield f"(sizeof (accessor_{position})),"
+        yield f"accessor_{normal}, // normal" if normal is not None else "NULL, // normal"
+        yield f"(sizeof (accessor_{normal}))," if normal is not None else "0,"
+        yield f"accessor_{texcoord_0}, // texcoord_0" if texcoord_0 is not None else "NULL, // texcoord_0"
+        yield f"(sizeof (accessor_{texcoord_0}))," if texcoord_0 is not None else "0,"
+        yield f"accessor_{weights_0}, // weights_0" if weights_0 is not None else "NULL, // weights_0"
+        yield f"(sizeof (accessor_{weights_0}))," if weights_0 is not None else "0,"
+        yield f"accessor_{joints_0}, // joints_0" if joints_0 is not None else "NULL, // joints_0"
+        yield f"(sizeof (accessor_{joints_0}))," if joints_0 is not None else "0,"
         yield f"accessor_{indices}, // indices"
+        yield f"(sizeof (accessor_{indices})),"
+
         yield "};"
 
 def render_nodes(gltf):
@@ -88,7 +99,7 @@ def render_nodes(gltf):
         if "skin" not in node:
             continue
         skin = node["skin"]
-        yield f"const Skin skin_{skin};"
+        yield f"extern const Skin skin_{skin};"
 
     for node_ix, node in enumerate(gltf.json["nodes"]):
         skin = f"&skin_{node['skin']}" if "skin" in node else "NULL"
@@ -107,9 +118,9 @@ def render_nodes(gltf):
         yield f"const Node node_{node_ix} = {{"
         yield f"{skin}, // skin"
         yield f"{mesh}, // mesh"
-        yield f"{render_value(scale, 'D3DXVECTOR3')}, // scale"
         yield f"{render_value(translation, 'D3DXVECTOR3')}, // translation"
         yield f"{render_value(rotation, 'D3DXVECTOR4')}, // rotation"
+        yield f"{render_value(scale, 'D3DXVECTOR3')}, // scale"
         yield "};"
 
 def render_skins(gltf):
@@ -123,7 +134,8 @@ def render_skins(gltf):
         inverse_bind_matrices = skin["inverseBindMatrices"]
         yield f"const Skin skin_{skin_ix} = {{"
         yield f"accessor_{inverse_bind_matrices}, // inverse bind matrices"
-        yield f"{{ skin_{skin_ix}__joints, {len(skin['joints'])} }},"
+        yield f"skin_{skin_ix}__joints, // joints"
+        yield f"{len(skin['joints'])}, // joints length"
         yield "};"
 
 def render_animation_samplers(animation_ix, samplers):
@@ -131,6 +143,7 @@ def render_animation_samplers(animation_ix, samplers):
         yield f"const AnimationSampler animation_{animation_ix}__sampler_{sampler_ix} = {{"
         yield f"accessor_{sampler['input']}, // input, keyframe timestamps"
         yield f"accessor_{sampler['output']}, // output, keyframe values (void *)"
+        yield f"accessor_{sampler['input']}_length, // length"
         yield "};"