当使用Assimp库加载GLTF模型时,有时会发现模型的网格不是按预期缩放的。这通常是由于模型导出时使用了不同的单位(例如cm,m或mm)导致的。
为了解决这个问题,可以通过以下代码来手动调整模型的比例:
// 载入模型
Assimp::Importer importer;
const aiScene* scene = importer.ReadFile("model.gltf", aiProcess_ValidateDataStructure);
// 获取根节点的变换
aiMatrix4x4 rootTransform = scene->mRootNode->mTransformation;
// 获取每个子节点网格的变换
for (unsigned int i = 0; i < scene->mNumMeshes; ++i)
{
aiMesh* mesh = scene->mMeshes[i];
aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];
aiString matName;
material->Get(AI_MATKEY_NAME, matName);
aiMatrix4x4 meshTransform = aiMatrix4x4();
aiNode* node = scene->mRootNode->FindNode(mesh->mName);
while (node)
{
meshTransform = node->mTransformation * meshTransform;
node = node->mParent;
}
// 计算缩放比例
aiVector3D scale;
meshTransform.Decompose(scale, aiQuaternion(), aiVector3D());
float scaleValue = (scale.x + scale.y + scale.z) / 3.0f;
// 将模型缩放到所需的大小
meshTransform = aiMatrix4x4::Scaling(aiVector3D(1.0f / scaleValue));
meshTransform = meshTransform * rootTransform;
// 将网格变换应用到顶点中
for (unsigned int j = 0; j < mesh->mNumVertices; ++j)
{
aiVector3D& vertex = mesh->mVertices[j];
aiVector3D transformedVertex = meshTransform * aiVector4D(vertex.x, vertex.y,