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#4109 #4080 Apply coordinate rotation to GLTF inverse bind matrices #4151

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Merged
merged 2 commits into from
May 23, 2025
Merged

#4109 #4080 Apply coordinate rotation to GLTF inverse bind matrices #4151

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047b2e8
#4109 #4080 Apply coordinate rotation to GLTF inverse bind matrices
marchcat May 22, 2025
43cf28e
#4109 #4080 Undistort GLTF rigged mesh in Z-up coordinate transformation
marchcat May 22, 2025
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62 changes: 49 additions & 13 deletions indra/newview/gltf/llgltfloader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -257,10 +257,6 @@ bool LLGLTFLoader::parseMeshes()
validate_model(pModel))
{
mModelList.push_back(pModel);
LLMatrix4 saved_transform = mTransform;

// This will make sure the matrix is always valid from the node.
node.makeMatrixValid();

mTransform.setIdentity();
transformation = mTransform;
Expand Down Expand Up @@ -292,7 +288,6 @@ bool LLGLTFLoader::parseMeshes()

mScene[transformation].push_back(LLModelInstance(pModel, pModel->mLabel, transformation, mats));
stretch_extents(pModel, transformation);
mTransform = saved_transform;
}
else
{
Expand Down Expand Up @@ -708,14 +703,30 @@ bool LLGLTFLoader::populateModelFromMesh(LLModel* pModel, const LL::GLTF::Mesh&
{
// Process bind matrix
LL::GLTF::mat4 gltf_mat = gltf_skin.mInverseBindMatricesData[i];
LLMatrix4 gltf_transform(glm::value_ptr(gltf_mat));

// For inverse bind matrices, we need to:
// 1. Get the original bind matrix by inverting
// 2. Apply coordinate rotation to the original
// 3. Invert again to get the rotated inverse bind matrix
glm::mat4 original_bind_matrix = glm::inverse(gltf_mat);
glm::mat4 coord_rotation = glm::rotate(glm::mat4(1.0f), glm::radians(90.0f), glm::vec3(1.0f, 0.0f, 0.0f));
glm::mat4 rotated_original = coord_rotation * original_bind_matrix;
glm::mat4 rotated_inverse_bind_matrix = glm::inverse(rotated_original);

LLMatrix4 gltf_transform(glm::value_ptr(rotated_inverse_bind_matrix));
skin_info.mInvBindMatrix.push_back(LLMatrix4a(gltf_transform));

LL_INFOS("GLTF") << "mInvBindMatrix name: " << legal_name << " val: " << gltf_transform << LL_ENDL;
LL_INFOS("GLTF_DEBUG") << "mInvBindMatrix name: " << legal_name << " val: " << gltf_transform << LL_ENDL;

// For alternate bind matrix, use the ORIGINAL joint transform (before rotation)
// Get the original joint node and use its matrix directly
S32 joint = gltf_skin.mJoints[i];
LL::GLTF::Node& jointNode = mGLTFAsset.mNodes[joint];
jointNode.makeMatrixValid();
LLMatrix4 original_joint_transform(glm::value_ptr(jointNode.mMatrix));

// Translate based of mJointList
gltf_transform.setTranslation(mJointList[legal_name].getTranslation()); // name is supposed to be in mJointList
skin_info.mAlternateBindMatrix.push_back(LLMatrix4a(gltf_transform));
LL_INFOS("GLTF_DEBUG") << "mAlternateBindMatrix name: " << legal_name << " val: " << original_joint_transform << LL_ENDL;
skin_info.mAlternateBindMatrix.push_back(LLMatrix4a(original_joint_transform));
}
}

Expand All @@ -742,6 +753,11 @@ bool LLGLTFLoader::populateModelFromMesh(LLModel* pModel, const LL::GLTF::Mesh&

void LLGLTFLoader::populateJointFromSkin(const LL::GLTF::Skin& skin)
{
// Create coordinate system rotation matrix - GLTF is Y-up, SL is Z-up
glm::mat4 coord_system_rotation = glm::rotate(glm::mat4(1.0f), glm::radians(90.0f), glm::vec3(1.0f, 0.0f, 0.0f));

LL_INFOS("GLTF_DEBUG") << "populateJointFromSkin: Processing " << skin.mJoints.size() << " joints" << LL_ENDL;

for (auto joint : skin.mJoints)
{
auto jointNode = mGLTFAsset.mNodes[joint];
Expand All @@ -754,17 +770,37 @@ void LLGLTFLoader::populateJointFromSkin(const LL::GLTF::Skin& skin)
else
{
// ignore unrecognized joint
LL_DEBUGS("GLTF") << "Ignoring joing: " << legal_name << LL_ENDL;
LL_DEBUGS("GLTF") << "Ignoring joint: " << legal_name << LL_ENDL;
continue;
}

jointNode.makeMatrixValid();

LLMatrix4 gltf_transform = LLMatrix4(glm::value_ptr(jointNode.mMatrix));
// Debug: Log original joint matrix
glm::mat4 gltf_joint_matrix = jointNode.mMatrix;
LL_INFOS("GLTF_DEBUG") << "Joint '" << legal_name << "' original matrix:" << LL_ENDL;
for(int i = 0; i < 4; i++)
{
LL_INFOS("GLTF_DEBUG") << " [" << gltf_joint_matrix[i][0] << ", " << gltf_joint_matrix[i][1]
<< ", " << gltf_joint_matrix[i][2] << ", " << gltf_joint_matrix[i][3] << "]" << LL_ENDL;
}

// Apply coordinate system rotation to joint transform
glm::mat4 rotated_joint_matrix = coord_system_rotation * gltf_joint_matrix;

// Debug: Log rotated joint matrix
LL_INFOS("GLTF_DEBUG") << "Joint '" << legal_name << "' rotated matrix:" << LL_ENDL;
for(int i = 0; i < 4; i++)
{
LL_INFOS("GLTF_DEBUG") << " [" << rotated_joint_matrix[i][0] << ", " << rotated_joint_matrix[i][1]
<< ", " << rotated_joint_matrix[i][2] << ", " << rotated_joint_matrix[i][3] << "]" << LL_ENDL;
}

LLMatrix4 gltf_transform = LLMatrix4(glm::value_ptr(rotated_joint_matrix));
mJointList[legal_name] = gltf_transform;
mJointsFromNode.push_front(legal_name);

LL_DEBUGS("GLTF") << "mJointList name: " << legal_name << " val: " << gltf_transform << LL_ENDL;
LL_INFOS("GLTF_DEBUG") << "mJointList name: " << legal_name << " val: " << gltf_transform << LL_ENDL;
}
}

Expand Down