From 9d9acf6840551d11423e32cd826d17b7da105d0f Mon Sep 17 00:00:00 2001 From: Tommy Date: Sun, 25 Feb 2018 11:45:38 +0100 Subject: [PATCH] FBX Export: allow export even when not in bind pose, iff all bones have an offset matrix defined. --- code/FBXExporter.cpp | 82 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 64 insertions(+), 18 deletions(-) diff --git a/code/FBXExporter.cpp b/code/FBXExporter.cpp index 6273f1977..f1c6290e2 100644 --- a/code/FBXExporter.cpp +++ b/code/FBXExporter.cpp @@ -1604,6 +1604,8 @@ void FBXExporter::WriteObjects () // TODO, FIXME: this won't work if anything is not in the bind pose. // for now if such a situation is detected, we throw an exception. + std::set not_in_bind_pose; + std::set no_offset_matrix; // first get this mesh's position in world space, // as we'll need it for each subdeformer. @@ -1612,10 +1614,6 @@ void FBXExporter::WriteObjects () // as it can be instanced to many nodes. // All we can do is assume no instancing, // and take the first node we find that contains the mesh. - // - // We could in stead take the transform from the bone's node, - // but there's no guarantee that the bone is in the bindpose, - // so this would be even less reliable. aiNode* mesh_node = get_node_for_mesh(mi, mScene->mRootNode); aiMatrix4x4 mesh_xform = get_world_transform(mesh_node, mScene); @@ -1632,6 +1630,9 @@ void FBXExporter::WriteObjects () break; } } + if (!b) { + no_offset_matrix.insert(bone_node); + } // start the subdeformer node const int64_t subdeformer_uid = generate_uid(); @@ -1669,30 +1670,52 @@ void FBXExporter::WriteObjects () } // transform is the transform of the mesh, but in bone space. - // To get it we take the inverse of the world-space bone transform, + // if the skeleton is in the bind pose, + // we can take the inverse of the world-space bone transform // and multiply by the world-space transform of the mesh. aiMatrix4x4 bone_xform = get_world_transform(bone_node, mScene); aiMatrix4x4 inverse_bone_xform = bone_xform; inverse_bone_xform.Inverse(); aiMatrix4x4 tr = inverse_bone_xform * mesh_xform; - sdnode.AddChild("Transform", tr); - // this should match assimp's mOffsetMatrix. - // if it doesn't then we have a problem. - // as assimp doesn't store a mOffsetMatrix for bones with 0 weight - // we have no way of reconstructing that information. + // this should be the same as the bone's mOffsetMatrix. + // if it's not the same, the skeleton isn't in the bind pose. const float epsilon = 1e-5; // some error is to be expected + bool bone_xform_okay = true; if (b && ! tr.Equal(b->mOffsetMatrix, epsilon)) { - std::stringstream err; - err << "transform matrix for bone \"" << b->mName.C_Str(); - err << "\" does not match mOffsetMatrix!"; - err << " Bones *must* be in the bind pose to export."; - throw DeadlyExportError(err.str()); + not_in_bind_pose.insert(b); + bone_xform_okay = false; } - // transformlink should be the position of the bone in world space, - // which we just calculated. - sdnode.AddChild("TransformLink", bone_xform); + // if we have a bone we should use the mOffsetMatrix, + // otherwise try to just use the calculated transform. + if (b) { + sdnode.AddChild("Transform", b->mOffsetMatrix); + } else { + sdnode.AddChild("Transform", tr); + } + // note: it doesn't matter if we mix these, + // because if they disagree we'll throw an exception later. + // it could be that the skeleton is not in the bone pose + // but all bones are still defined, + // in which case this would use the mOffsetMatrix for everything + // and a correct skeleton would still be output. + + // transformlink should be the position of the bone in world space. + // if the bone is in the bind pose (or nonexistant), + // we can just use the matrix we already calculated + if (bone_xform_okay) { + sdnode.AddChild("TransformLink", bone_xform); + // otherwise we can only work it out using the mesh position. + } else { + aiMatrix4x4 trl = b->mOffsetMatrix; + trl.Inverse(); + trl *= mesh_xform; + sdnode.AddChild("TransformLink", trl); + } + // note: this means we ALWAYS rely on the mesh node transform + // being unchanged from the time the skeleton was bound. + // there's not really any way around this at the moment. // done sdnode.Dump(outstream); @@ -1708,6 +1731,29 @@ void FBXExporter::WriteObjects () connections.push_back(c); // TODO: emplace_back } + // if we cannot create a valid FBX file, simply die. + // this will both prevent unnecessary bug reports, + // and tell the user what they can do to fix the situation + // (i.e. export their model in the bind pose). + if (no_offset_matrix.size() && not_in_bind_pose.size()) { + std::stringstream err; + err << "Not enough information to construct bind pose"; + err << " for mesh " << mi << "!"; + err << " Transform matrix for bone \""; + err << (*not_in_bind_pose.begin())->mName.C_Str() << "\""; + if (not_in_bind_pose.size() > 1) { + err << " (and " << not_in_bind_pose.size() - 1 << " more)"; + } + err << " does not match mOffsetMatrix,"; + err << " and node \""; + err << (*no_offset_matrix.begin())->mName.C_Str() << "\""; + if (no_offset_matrix.size() > 1) { + err << " (and " << no_offset_matrix.size() - 1 << " more)"; + } + err << " has no offset matrix to rely on."; + err << " Please ensure bones are in the bind pose to export."; + throw DeadlyExportError(err.str()); + } }