From 90d9d72530a893872e2413139410f5fcd48cb387 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Sat, 17 Feb 2024 20:19:46 -0800
Subject: Remove joint nodes after the model anima is loaded.

---
 gfx/src/asset/model.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/gfx/src/asset/model.c b/gfx/src/asset/model.c
index 73ce731..05e6e91 100644
--- a/gfx/src/asset/model.c
+++ b/gfx/src/asset/model.c
@@ -986,7 +986,7 @@ static bool load_meshes(
         const cgltf_buffer_view* view         = accessor->buffer_view;
         const cgltf_size         offset       = accessor->offset + view->offset;
         const cgltf_size         buffer_index = view->buffer - data->buffers;
-        
+
         assert(buffer_index < data->buffers_count);
         Buffer* buffer = buffers[buffer_index];
 
@@ -1492,6 +1492,66 @@ static void load_nodes(
   } // SceneNode.
 }
 
+/// Remove joint nodes from the Gfx Scene.
+///
+/// Joint nodes are not needed because joints are packed into the Anima.
+static void remove_joint_nodes(
+    const cgltf_data* data, SceneNode** scene_nodes) {
+  assert(data);
+  assert(scene_nodes);
+
+  // This works assuming the joint nodes are contiguous. Contiguity is checked
+  // when loading skins. See load_skins().
+  size_t min_joint_index = (size_t)-1;
+  size_t max_joint_index = 0;
+
+  // First get the minimum and maximum indices of all joint nodes.
+  for (cgltf_size s = 0; s < data->skins_count; ++s) {
+    const cgltf_skin* skin = &data->skins[s];
+
+    for (cgltf_size j = 0; j < skin->joints_count; ++j) {
+      // Joint is an index/pointer into the nodes array.
+      const cgltf_size joint_index = skin->joints[j] - data->nodes;
+      assert(joint_index < data->nodes_count);
+
+      if (joint_index < min_joint_index) {
+        min_joint_index = joint_index;
+      }
+      if (joint_index > max_joint_index) {
+        max_joint_index = joint_index;
+      }
+    }
+  }
+
+  assert(min_joint_index < data->nodes_count);
+  assert(max_joint_index < data->nodes_count);
+
+  // Now walk over the joint nodes. If a joint's parent is itself not a joint
+  // node, then that joint is a root of a joint hierarchy (skins in glTF may
+  // have multiple roots). In such case, delete the root joint recursively.
+  for (cgltf_size s = 0; s < data->skins_count; ++s) {
+    const cgltf_skin* skin = &data->skins[s];
+
+    for (cgltf_size j = 0; j < skin->joints_count; ++j) {
+      // Joint is an index/pointer into the nodes array.
+      const cgltf_size joint_index = skin->joints[j] - data->nodes;
+      assert(joint_index < data->nodes_count);
+
+      const cgltf_node* joint = &data->nodes[joint_index];
+
+      // Parent node index.
+      const cgltf_size parent_index = joint->parent - data->nodes;
+      assert(parent_index < data->nodes_count);
+
+      // If the parent is not a joint node, recursively delete this joint node.
+      if ((parent_index < min_joint_index) ||
+          (parent_index > max_joint_index)) {
+        gfx_destroy_node(&scene_nodes[joint_index]);
+      }
+    }
+  }
+}
+
 /// Load all scenes from the glTF file.
 ///
 /// If the scene is loaded from memory, set filepath = null.
@@ -1629,7 +1689,11 @@ static Model* load_scene(
   // The root node becomes the root of all scene nodes.
   load_nodes(data, root_node, scene_objects, scene_cameras, anima, scene_nodes);
 
-  // TODO: Clean up scene nodes that correspond to joints in the glTF.
+  // Clean up scene nodes that correspond to joints in the glTF. These are
+  // not needed anymore.
+  if (data->skins_count > 0) {
+    remove_joint_nodes(data, scene_nodes);
+  }
 
   model = gfx_make_model(root_node);
 
-- 
cgit v1.2.3