fix: handle non-contiguous xmodel root bones (#1009)

* fix: handle non-contiguous xmodel root bones * chore: add comment about invalid parent index fix --------- Co-authored-by: Jan Laupetin <[email protected]>
2026-09-22 22:07:08 +00:00 · 2026-09-21 21:23:25 +02:00
parent fc1a0bbc38
commit 209d0105c3
3 changed files with 117 additions and 10 deletions
@@ -0,0 +1,96 @@
+#include "Game/T4/XModel/XModelToCommonConverterT4.h"
+#include "XModel/Gltf/GltfWriter.h"
+
+#include <array>
+#include <catch2/catch_test_macros.hpp>
+#include <nlohmann/json.hpp>
+#include <optional>
+#include <string>
+
+using namespace T4;
+
+namespace
+{
+    class MockGltfOutput final : public gltf::Output
+    {
+    public:
+        std::optional<std::string> CreateBufferUri(const void* buffer, size_t bufferSize) const override
+        {
+            return std::nullopt;
+        }
+
+        void EmitJson(const nlohmann::ordered_json& json) const override
+        {
+            m_json = json;
+        }
+
+        void EmitBuffer(const void* buffer, size_t bufferSize) const override {}
+
+        void Finalize() const override {}
+
+        mutable nlohmann::ordered_json m_json;
+    };
+
+    TEST_CASE("XModelGltfWriterT4: Can write a non-contiguous root bone", "[t4][xmodel][gltf]")
+    {
+        constexpr std::array boneNameValues{
+            "tag_weapon",
+            "tag_brass",
+            "tag_flash",
+            "tag_sights",
+            "tag_sights_front",
+            "tag_clip",
+        };
+
+        Zone zone("MockZone", 0, GameId::T4, GamePlatform::PC);
+
+        std::array<ScriptString, boneNameValues.size()> boneNames{};
+        for (auto boneIndex = 0u; boneIndex < boneNameValues.size(); boneIndex++)
+            boneNames[boneIndex] = zone.m_script_strings.AddOrGetScriptString(boneNameValues[boneIndex]);
+
+        // The final offset is malformed in the source model: bone 5 minus 6 would be -1.
+        // Treating the subtraction as unsigned used to turn this into UINT_MAX and crash the GLTF writer.
+        std::array<unsigned char, boneNameValues.size() - 1> parentList{1, 2, 3, 4, 6};
+        std::array<XModelQuat, boneNameValues.size() - 1> quats{};
+        std::array<float, (boneNameValues.size() - 1) * 3> trans{};
+        std::array<DObjAnimMat, boneNameValues.size()> baseMats{};
+        for (auto& baseMat : baseMats)
+            baseMat.quat.w = 1.0f;
+
+        XModel model{};
+        model.name = "bo2_worldmodel_an94";
+        model.numBones = static_cast<unsigned char>(boneNames.size());
+        model.numRootBones = 1;
+        model.boneNames = boneNames.data();
+        model.parentList = parentList.data();
+        model.quats = quats.data();
+        model.trans = trans.data();
+        model.baseMat = baseMats.data();
+        model.numLods = 1;
+
+        XAssetInfo<XModel> assetInfo(ASSET_TYPE_XMODEL, model.name, &model);
+        assetInfo.m_zone = &zone;
+
+        xmodel::ToCommonConverterT4 converter;
+        const auto common = converter.Convert(assetInfo, 0);
+
+        REQUIRE(common.has_value());
+        REQUIRE(common->m_bones.size() == boneNameValues.size());
+        REQUIRE(common->m_bones[0].parentIndex == std::nullopt);
+        REQUIRE(common->m_bones[1].parentIndex == 0u);
+        REQUIRE(common->m_bones[2].parentIndex == 0u);
+        REQUIRE(common->m_bones[3].parentIndex == 0u);
+        REQUIRE(common->m_bones[4].parentIndex == 0u);
+        REQUIRE(common->m_bones[5].parentIndex == std::nullopt);
+
+        MockGltfOutput output;
+        const auto writer = gltf::Writer::CreateWriter(&output, "T4", zone.m_name);
+        writer->Write(*common);
+
+        REQUIRE(output.m_json["nodes"].size() == 7);
+        REQUIRE(output.m_json["nodes"][0]["children"] == nlohmann::ordered_json::array({1, 2, 3, 4}));
+        REQUIRE(output.m_json["nodes"][6]["children"] == nlohmann::ordered_json::array({0, 5}));
+        REQUIRE(output.m_json["skins"].size() == 1);
+        REQUIRE_FALSE(output.m_json["skins"][0].contains("skeleton"));
+    }
+} // namespace