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fix: preserve material IDs and image data in GLB export #2

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fix: preserve material IDs and image data in GLB export #2

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3 changes: 2 additions & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,10 @@ target_compile_options(VCGCoreStatic PRIVATE $<$<CXX_COMPILER_ID:MSVC>:/utf-8>)

add_executable(vcg-simplifier ${CLI_SOURCES})

target_link_libraries(vcg-simplifier PRIVATE VCGCoreStatic)
target_link_libraries(vcg-simplifier PRIVATE VCGCoreStatic VCGSimplifier)
target_include_directories(vcg-simplifier PRIVATE ${SRC_DIR}/cli/Public)
target_include_directories(vcg-simplifier PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include)
target_include_directories(vcg-simplifier PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
target_include_directories(vcg-simplifier PRIVATE ${TINYGLTF_INCLUDE_DIRS})
target_compile_definitions(vcg-simplifier PRIVATE _CRT_SECURE_NO_WARNINGS)
target_compile_options(vcg-simplifier PRIVATE $<$<CXX_COMPILER_ID:MSVC>:/utf-8>)
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67 changes: 51 additions & 16 deletions src/cli/glb_loader.cpp
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Expand Up @@ -229,18 +229,11 @@ bool SaveGLB(MyMesh &m, const tinygltf::Model &originalModel, const std::string
outModel.asset = originalModel.asset;
outModel.asset.generator = "VCG-Simplifier";

// 【关键修复】处理图片和纹理引用
outModel.materials = originalModel.materials;
outModel.textures = originalModel.textures;
outModel.samplers = originalModel.samplers;
outModel.images = originalModel.images;

// 清除 BufferView 索引，强制 TinyGLTF 重新打包图片数据
for (auto &img : outModel.images) {
img.bufferView = -1;
img.uri = "";
}

// 2. 准备几何数据容器
std::vector<float> rawPos;
std::vector<float> rawNor;
Expand Down Expand Up @@ -350,7 +343,7 @@ bool SaveGLB(MyMesh &m, const tinygltf::Model &originalModel, const std::string
allIndices.insert(allIndices.end(), pair.second.begin(), pair.second.end());
}

// 3. 构建二进制 Buffer
// 3. 构建二进制 Buffer (几何 + 原始图片数据)
tinygltf::Buffer buffer;

size_t lenPos = rawPos.size() * sizeof(float);
Expand All @@ -365,23 +358,46 @@ bool SaveGLB(MyMesh &m, const tinygltf::Model &originalModel, const std::string
size_t offsetCol = offsetUV + lenUV;
size_t offsetInd = offsetCol + lenCol;

size_t totalSize = offsetInd + lenInd;

// 【关键修复】Buffer 总长度必须是 4 的倍数 (Padding)
size_t padding = 0;
if (totalSize % 4 != 0) {
padding = 4 - (totalSize % 4);
size_t geoEnd = offsetInd + lenInd;
if (geoEnd % 4 != 0) geoEnd += 4 - (geoEnd % 4);

// Collect raw image bytes from original buffer
struct ImgEntry { size_t srcOffset; size_t length; std::string mimeType; };
std::vector<ImgEntry> imgEntries;
size_t imgTotalSize = 0;
for (const auto &img : originalModel.images) {
if (img.bufferView >= 0 && !originalModel.buffers.empty()) {
const auto &bv = originalModel.bufferViews[img.bufferView];
size_t aligned = bv.byteLength;
if (aligned % 4 != 0) aligned += 4 - (aligned % 4);
imgEntries.push_back({bv.byteOffset, bv.byteLength, img.mimeType});
imgTotalSize += aligned;
} else {
imgEntries.push_back({0, 0, ""});
}
}

buffer.data.resize(totalSize + padding);
buffer.data.resize(geoEnd + imgTotalSize, 0);

// 写入数据
std::memcpy(buffer.data.data() + offsetPos, rawPos.data(), lenPos);
std::memcpy(buffer.data.data() + offsetNor, rawNor.data(), lenNor);
std::memcpy(buffer.data.data() + offsetUV, rawUV.data(), lenUV);
std::memcpy(buffer.data.data() + offsetCol, rawColorUB.data(), lenCol);
std::memcpy(buffer.data.data() + offsetInd, allIndices.data(), lenInd);

// Copy image data and update image references
size_t imgWriteOffset = geoEnd;
const auto &srcBuf = originalModel.buffers[0].data;
for (size_t i = 0; i < imgEntries.size(); ++i) {
if (imgEntries[i].length == 0) continue;
std::memcpy(buffer.data.data() + imgWriteOffset,
srcBuf.data() + imgEntries[i].srcOffset,
imgEntries[i].length);
imgWriteOffset += imgEntries[i].length;
if (imgWriteOffset % 4 != 0)
imgWriteOffset += 4 - (imgWriteOffset % 4);
}

outModel.buffers.push_back(buffer);
int bufferId = 0;

Expand All @@ -402,6 +418,25 @@ bool SaveGLB(MyMesh &m, const tinygltf::Model &originalModel, const std::string
int bvCol = addBufferView(offsetCol, lenCol, TINYGLTF_TARGET_ARRAY_BUFFER);
int bvInd = addBufferView(offsetInd, lenInd, TINYGLTF_TARGET_ELEMENT_ARRAY_BUFFER);

// Image bufferViews — keep images in BIN chunk
size_t imgBvOffset = geoEnd;
for (size_t i = 0; i < imgEntries.size(); ++i) {
if (imgEntries[i].length == 0) continue;
tinygltf::BufferView bv;
bv.buffer = bufferId;
bv.byteOffset = imgBvOffset;
bv.byteLength = imgEntries[i].length;
bv.target = 0;
int bvIdx = (int)outModel.bufferViews.size();
outModel.bufferViews.push_back(bv);
outModel.images[i].bufferView = bvIdx;
outModel.images[i].mimeType = imgEntries[i].mimeType;
outModel.images[i].uri = "";
imgBvOffset += imgEntries[i].length;
if (imgBvOffset % 4 != 0)
imgBvOffset += 4 - (imgBvOffset % 4);
}

// 5. 创建 Accessors
// 【关键修复】参数 typeEnum 改为 int，并接收 Min/Max
auto addAccessor = [&](int bv, int count, int compType, int typeEnum,
Expand Down
50 changes: 49 additions & 1 deletion src/cli/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,9 @@
#include "mymesh.h"
#include "obj_loader.h"
#include <cstdio>
#include <cmath>
#include <map>
#include <vector>

// --- 主程序 ---
void LogStatus(MyMesh &m, const char *stage) { printf("[%s] V:%d F:%d\n", stage, m.VN(), m.FN()); }
Expand Down Expand Up @@ -125,6 +128,17 @@ int main(int argc, char **argv) {
vcgData.wedge_tangents = wtangents.data();
vcgData.wedge_binormal_signs = wb_signs.data();

// Save original face centroids + matId for post-simplification recovery
struct OrigFaceInfo { float cx, cy, cz; int matId; };
std::vector<OrigFaceInfo> origFaces(vcgData.num_faces);
for (int i = 0; i < vcgData.num_faces; ++i) {
int i0 = idx[i*3+0], i1 = idx[i*3+1], i2 = idx[i*3+2];
origFaces[i].cx = (pos[i0*3+0]+pos[i1*3+0]+pos[i2*3+0]) / 3.0f;
origFaces[i].cy = (pos[i0*3+1]+pos[i1*3+1]+pos[i2*3+1]) / 3.0f;
origFaces[i].cz = (pos[i0*3+2]+pos[i1*3+2]+pos[i2*3+2]) / 3.0f;
origFaces[i].matId = mat_id[i];
}

printf("Calling CreateMesh...\n");
// ======= C API 调用 =======
VCGMeshHandle handle = VCG_CreateMesh();
Expand All @@ -142,7 +156,41 @@ int main(int argc, char **argv) {
printf("Calling GetMeshData...\n");
fflush(stdout);
VCG_GetMeshData(handle, &vcgData);
printf("API done. Unpacking data...\n");
printf("API done. Recovering material IDs...\n");
printf(" Result: V=%d F=%d\n", vcgData.num_vertices, vcgData.num_faces);

// Recover matId by nearest-centroid matching
for (int i = 0; i < vcgData.num_faces; ++i) {
int i0 = vcgData.indices[i*3+0];
int i1 = vcgData.indices[i*3+1];
int i2 = vcgData.indices[i*3+2];
float cx = (vcgData.positions[i0*3+0]+vcgData.positions[i1*3+0]+vcgData.positions[i2*3+0]) / 3.0f;
float cy = (vcgData.positions[i0*3+1]+vcgData.positions[i1*3+1]+vcgData.positions[i2*3+1]) / 3.0f;
float cz = (vcgData.positions[i0*3+2]+vcgData.positions[i1*3+2]+vcgData.positions[i2*3+2]) / 3.0f;

float bestDist = 1e30f;
int bestMat = 0;
for (int j = 0; j < (int)origFaces.size(); ++j) {
float dx = cx - origFaces[j].cx;
float dy = cy - origFaces[j].cy;
float dz = cz - origFaces[j].cz;
float d = dx*dx + dy*dy + dz*dz;
if (d < bestDist) {
bestDist = d;
bestMat = origFaces[j].matId;
if (d == 0.0f) break;
}
}
vcgData.material_ids[i] = bestMat;
}

{
std::map<int, int> matCount;
for (int i = 0; i < vcgData.num_faces; ++i)
matCount[vcgData.material_ids[i]]++;
for (auto &p : matCount)
printf(" matId=%d count=%d\n", p.first, p.second);
}
fflush(stdout);
// ======= 更新 MyMesh =======
m.Clear();
Expand Down