From b052718d7e30a46c831aa8dfc8d935bbdda0b2e5 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Mon, 26 Jan 2026 21:19:53 -0600
Subject: [PATCH] collada/header: reference node transforms by index rather
 than by type

---
 collada/header.py                      | 29 ++++++++++++++++----------
 include/collada_types.hpp              |  2 +-
 include/scenes/curve_interpolation.hpp | 16 +++++++-------
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/collada/header.py b/collada/header.py
index 98ae9b3..6425126 100644
--- a/collada/header.py
+++ b/collada/header.py
@@ -549,15 +549,20 @@ target_attributes = {
     "A", "ANGLE", "B", "G", "P", "Q", "R", "S", "T", "TIME", "U", "V", "W", "X", "Y", "Z"
 }
 
-def render_transform_type(transformation_element):
-    return {
-        types.Lookat: "LOOKAT",
-        types.Matrix: "MATRIX",
-        types.Rotate: "ROTATE",
-        types.Scale: "SCALE",
-        types.Skew: "SKEW",
-        types.Translate: "TRANSLATE",
-    }[type(transformation_element)]
+def find_transform_index_in_node(node, transform):
+    for i, node_transform in enumerate(node.transformation_elements):
+        if node_transform is transform:
+            return i
+    assert False, (node, transform)
+
+def transform_sid_lookup(node, sid):
+    transform_types = {
+        types.Lookat, types.Matrix, types.Rotate,
+        types.Scale, types.Skew, types.Translate
+    }
+    transform = node.sid_lookup[sid]
+    assert type(transform) in transform_types, transform
+    return transform
 
 def render_channel(state, collada, channel):
     sampler = collada.lookup(channel.source, types.Sampler)
@@ -574,7 +579,9 @@ def render_channel(state, collada, channel):
     node = collada.lookup(f"#{node_id}", types.Node)
     node_name_id = get_node_name_id(node)
     node_name = sanitize_name(state, node_name_id, node)
-    transformation_element = node.sid_lookup[node_transform_sid]
+
+    transform = transform_sid_lookup(node, node_transform_sid)
+    transform_index = find_transform_index_in_node(node, transform)
 
     target_name = sanitize_name(state, channel.target, channel, allow_slash=True)
     assert target_name not in state.node_animation_channels[node.id]
@@ -582,7 +589,7 @@ def render_channel(state, collada, channel):
 
     yield f"channel const node_channel_{target_name} = {{"
     yield f".source_sampler = &sampler_{sampler_name},"
-    yield f".target_transform_type = transform_type::{render_transform_type(transformation_element)},"
+    yield f".target_transform_index = {transform_index},"
     yield f".target_attribute = target_attribute::{target_attribute},"
     yield "};"
 
diff --git a/include/collada_types.hpp b/include/collada_types.hpp
index 3fd3d08..a1a23bf 100644
--- a/include/collada_types.hpp
+++ b/include/collada_types.hpp
@@ -257,7 +257,7 @@ namespace collada {
   struct channel {
     sampler const * const source_sampler;
     int const target_node_index; // an index into the nodes array
-    transform_type const target_transform_type;
+    int const target_transform_index;
     target_attribute const target_attribute;
   };
 
diff --git a/include/scenes/curve_interpolation.hpp b/include/scenes/curve_interpolation.hpp
index 2da5128..09691e8 100644
--- a/include/scenes/curve_interpolation.hpp
+++ b/include/scenes/curve_interpolation.hpp
@@ -132,13 +132,13 @@ sampler const sampler_node_cube_translation_y_sampler = {
 
 channel const node_channel_node_cube_translation_x = {
   .source_sampler = &sampler_node_cube_translation_x_sampler,
-  .target_transform_type = transform_type::TRANSLATE,
+  .target_transform_index = 0,
   .target_attribute = target_attribute::X,
 };
 
 channel const node_channel_node_cube_translation_y = {
   .source_sampler = &sampler_node_cube_translation_y_sampler,
-  .target_transform_type = transform_type::TRANSLATE,
+  .target_transform_index = 0,
   .target_attribute = target_attribute::Y,
 };
 
@@ -543,7 +543,7 @@ node const * const node_children_node_cube = {
 transform const transforms_node_cube[] = {
   {
     .type = transform_type::TRANSLATE,
-    .translate = {10.0f, 0.0f, 0.0f},
+    .translate = {10.0f, -1.14258e-07f, 0.0f},
   },
 };
 
@@ -552,6 +552,10 @@ instance_material const instance_materials_node_cube_0[] = {
     .element_index = 1, // an index into mesh.triangles
     .material = &material_material__15_material,
   },
+  {
+    .element_index = 0, // an index into mesh.triangles
+    .material = &material_material__16_material,
+  },
   {
     .element_index = 5, // an index into mesh.triangles
     .material = &material_material__17_material,
@@ -564,10 +568,6 @@ instance_material const instance_materials_node_cube_0[] = {
     .element_index = 2, // an index into mesh.triangles
     .material = &material_material__19_material,
   },
-  {
-    .element_index = 0, // an index into mesh.triangles
-    .material = &material_material__16_material,
-  },
   {
     .element_index = 4, // an index into mesh.triangles
     .material = &material_material__20_material,
@@ -583,8 +583,8 @@ instance_geometry const instance_geometries_node_cube[] = {
 };
 
 channel const * const node_channels_node_cube[] = {
-  &node_channel_node_cube_translation_x,
   &node_channel_node_cube_translation_y,
+  &node_channel_node_cube_translation_x,
 };
 
 node const node_node_cube = {