Support up to 16 joints

Author: luanpotter

packages/flame_3d/assets/shaders/spatial_material.shaderbundle

@@ -21,13 +21,10 @@ class SpatialMaterial extends Material {
                 'view',
                 'projection',
               }),
-              UniformSlot.value('JointMatrices', {
-                'joint0',
-                'joint1',
-                'joint2',
-                'joint3',
-                'joint4',
-              }),
+              UniformSlot.value(
+                'JointMatrices',
+                List.generate(_maxJoints, (idx) => 'joint$idx').toSet(),
+              ),
             ],
           ),
           fragmentShader: Shader(
@@ -81,9 +78,9 @@ class SpatialMaterial extends Material {
 
   void _bindJointMatrices(GraphicsDevice device) {
     final jointTransforms = device.jointsInfo.jointTransforms;
-    if (jointTransforms.length > 5) {
+    if (jointTransforms.length > _maxJoints) {
       throw Exception(
-        'At most 5 joints per surface, found ${jointTransforms.length}',
+        'At most $_maxJoints joints per surface, found ${jointTransforms.length}',
       );
     }
     for (final (idx, transform) in jointTransforms.indexed) {
@@ -113,4 +110,6 @@ class SpatialMaterial extends Material {
   static final _library = gpu.ShaderLibrary.fromAsset(
     'packages/flame_3d/assets/shaders/spatial_material.shaderbundle',
   )!;
+
+  static const _maxJoints = 16;
 }

packages/flame_3d/lib/src/resources/material/spatial_material.dart

@@ -3,6 +3,7 @@ import 'dart:typed_data';
 
 import 'package:flame_3d/graphics.dart';
 import 'package:flame_3d/resources.dart';
+import 'package:ordered_set/comparing.dart';
 
 /// {@template uniform_value}
 /// Instance of a uniform value. Represented by a [ByteBuffer].
@@ -21,7 +22,9 @@ class UniformValue extends UniformInstance<ByteBuffer> {
     if (super.resource == null) {
       var previousIndex = -1;
 
-      final data = _storage.entries.fold<List<double>>([], (p, e) {
+      final entries = _storage.entries.toList()
+        ..sort(Comparing.on((c) => c.key));
+      final data = entries.fold<List<double>>([], (p, e) {
         if (previousIndex + 1 != e.key) {
           final field =
               slot.fields.indexed.firstWhere((e) => e.$1 == previousIndex + 1);

packages/flame_3d/lib/src/resources/shader/uniform_value.dart

@@ -18,6 +18,7 @@ dependencies:
   flutter_gpu:
     sdk: flutter
   meta: ^1.12.0
+  ordered_set: ^6.0.1
   vector_math: ^2.1.4
 
 dev_dependencies:

packages/flame_3d/pubspec.yaml

@@ -24,6 +24,17 @@ uniform JointMatrices {
   mat4 joint2;
   mat4 joint3;
   mat4 joint4;
+  mat4 joint5;
+  mat4 joint6;
+  mat4 joint7;
+  mat4 joint8;
+  mat4 joint9;
+  mat4 joint10;
+  mat4 joint11;
+  mat4 joint12;
+  mat4 joint13;
+  mat4 joint14;
+  mat4 joint15;
 } joints;
 
 mat4 jointMat(float jointIndex) {
@@ -37,6 +48,28 @@ mat4 jointMat(float jointIndex) {
     return joints.joint3;
   } else if (jointIndex == 4.0) {
     return joints.joint4;
+  } else if (jointIndex == 5.0) {
+    return joints.joint5;
+  } else if (jointIndex == 6.0) {
+    return joints.joint6;
+  } else if (jointIndex == 7.0) {
+    return joints.joint7;
+  } else if (jointIndex == 8.0) {
+    return joints.joint8;
+  } else if (jointIndex == 9.0) {
+    return joints.joint9;
+  } else if (jointIndex == 10.0) {
+    return joints.joint10;
+  } else if (jointIndex == 11.0) {
+    return joints.joint11;
+  } else if (jointIndex == 12.0) {
+    return joints.joint12;
+  } else if (jointIndex == 13.0) {
+    return joints.joint13;
+  } else if (jointIndex == 14.0) {
+    return joints.joint14;
+  } else if (jointIndex == 15.0) {
+    return joints.joint15;
   } else {
     return mat4(0.0);
   }