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Diffstat (limited to 'extern/draco/draco/src/draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_encoder.h')
| -rw-r--r-- | extern/draco/draco/src/draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_encoder.h | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_encoder.h b/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_encoder.h new file mode 100644 index 00000000000..813b72ae35f --- /dev/null +++ b/extern/draco/draco/src/draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_tex_coords_encoder.h @@ -0,0 +1,318 @@ +// Copyright 2016 The Draco Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +#ifndef DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_ENCODER_H_ +#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_ENCODER_H_ + +#include <math.h> + +#include "draco/compression/attributes/prediction_schemes/mesh_prediction_scheme_encoder.h" +#include "draco/compression/bit_coders/rans_bit_encoder.h" +#include "draco/core/varint_encoding.h" +#include "draco/core/vector_d.h" +#include "draco/mesh/corner_table.h" + +namespace draco { + +// Prediction scheme designed for predicting texture coordinates from known +// spatial position of vertices. For good parametrization, the ratios between +// triangle edge lengths should be about the same in both the spatial and UV +// coordinate spaces, which makes the positions a good predictor for the UV +// coordinates. +template <typename DataTypeT, class TransformT, class MeshDataT> +class MeshPredictionSchemeTexCoordsEncoder + : public MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT> { + public: + using CorrType = typename MeshPredictionSchemeEncoder<DataTypeT, TransformT, + MeshDataT>::CorrType; + MeshPredictionSchemeTexCoordsEncoder(const PointAttribute *attribute, + const TransformT &transform, + const MeshDataT &mesh_data) + : MeshPredictionSchemeEncoder<DataTypeT, TransformT, MeshDataT>( + attribute, transform, mesh_data), + pos_attribute_(nullptr), + entry_to_point_id_map_(nullptr), + num_components_(0) {} + + bool ComputeCorrectionValues( + const DataTypeT *in_data, CorrType *out_corr, int size, + int num_components, const PointIndex *entry_to_point_id_map) override; + + bool EncodePredictionData(EncoderBuffer *buffer) override; + + PredictionSchemeMethod GetPredictionMethod() const override { + return MESH_PREDICTION_TEX_COORDS_DEPRECATED; + } + + bool IsInitialized() const override { + if (pos_attribute_ == nullptr) { + return false; + } + if (!this->mesh_data().IsInitialized()) { + return false; + } + return true; + } + + int GetNumParentAttributes() const override { return 1; } + + GeometryAttribute::Type GetParentAttributeType(int i) const override { + DRACO_DCHECK_EQ(i, 0); + (void)i; + return GeometryAttribute::POSITION; + } + + bool SetParentAttribute(const PointAttribute *att) override { + if (att->attribute_type() != GeometryAttribute::POSITION) { + return false; // Invalid attribute type. + } + if (att->num_components() != 3) { + return false; // Currently works only for 3 component positions. + } + pos_attribute_ = att; + return true; + } + + protected: + Vector3f GetPositionForEntryId(int entry_id) const { + const PointIndex point_id = entry_to_point_id_map_[entry_id]; + Vector3f pos; + pos_attribute_->ConvertValue(pos_attribute_->mapped_index(point_id), + &pos[0]); + return pos; + } + + Vector2f GetTexCoordForEntryId(int entry_id, const DataTypeT *data) const { + const int data_offset = entry_id * num_components_; + return Vector2f(static_cast<float>(data[data_offset]), + static_cast<float>(data[data_offset + 1])); + } + + void ComputePredictedValue(CornerIndex corner_id, const DataTypeT *data, + int data_id); + + private: + const PointAttribute *pos_attribute_; + const PointIndex *entry_to_point_id_map_; + std::unique_ptr<DataTypeT[]> predicted_value_; + int num_components_; + // Encoded / decoded array of UV flips. + std::vector<bool> orientations_; +}; + +template <typename DataTypeT, class TransformT, class MeshDataT> +bool MeshPredictionSchemeTexCoordsEncoder<DataTypeT, TransformT, MeshDataT>:: + ComputeCorrectionValues(const DataTypeT *in_data, CorrType *out_corr, + int size, int num_components, + const PointIndex *entry_to_point_id_map) { + num_components_ = num_components; + entry_to_point_id_map_ = entry_to_point_id_map; + predicted_value_ = + std::unique_ptr<DataTypeT[]>(new DataTypeT[num_components]); + this->transform().Init(in_data, size, num_components); + // We start processing from the end because this prediction uses data from + // previous entries that could be overwritten when an entry is processed. + for (int p = + static_cast<int>(this->mesh_data().data_to_corner_map()->size()) - 1; + p >= 0; --p) { + const CornerIndex corner_id = this->mesh_data().data_to_corner_map()->at(p); + ComputePredictedValue(corner_id, in_data, p); + + const int dst_offset = p * num_components; + this->transform().ComputeCorrection( + in_data + dst_offset, predicted_value_.get(), out_corr + dst_offset); + } + return true; +} + +template <typename DataTypeT, class TransformT, class MeshDataT> +bool MeshPredictionSchemeTexCoordsEncoder<DataTypeT, TransformT, MeshDataT>:: + EncodePredictionData(EncoderBuffer *buffer) { + // Encode the delta-coded orientations using arithmetic coding. + const uint32_t num_orientations = static_cast<uint32_t>(orientations_.size()); + EncodeVarint(num_orientations, buffer); + bool last_orientation = true; + RAnsBitEncoder encoder; + encoder.StartEncoding(); + for (bool orientation : orientations_) { + encoder.EncodeBit(orientation == last_orientation); + last_orientation = orientation; + } + encoder.EndEncoding(buffer); + return MeshPredictionSchemeEncoder<DataTypeT, TransformT, + MeshDataT>::EncodePredictionData(buffer); +} + +template <typename DataTypeT, class TransformT, class MeshDataT> +void MeshPredictionSchemeTexCoordsEncoder<DataTypeT, TransformT, MeshDataT>:: + ComputePredictedValue(CornerIndex corner_id, const DataTypeT *data, + int data_id) { + // Compute the predicted UV coordinate from the positions on all corners + // of the processed triangle. For the best prediction, the UV coordinates + // on the next/previous corners need to be already encoded/decoded. + const CornerIndex next_corner_id = + this->mesh_data().corner_table()->Next(corner_id); + const CornerIndex prev_corner_id = + this->mesh_data().corner_table()->Previous(corner_id); + // Get the encoded data ids from the next and previous corners. + // The data id is the encoding order of the UV coordinates. + int next_data_id, prev_data_id; + + int next_vert_id, prev_vert_id; + next_vert_id = + this->mesh_data().corner_table()->Vertex(next_corner_id).value(); + prev_vert_id = + this->mesh_data().corner_table()->Vertex(prev_corner_id).value(); + + next_data_id = this->mesh_data().vertex_to_data_map()->at(next_vert_id); + prev_data_id = this->mesh_data().vertex_to_data_map()->at(prev_vert_id); + + if (prev_data_id < data_id && next_data_id < data_id) { + // Both other corners have available UV coordinates for prediction. + const Vector2f n_uv = GetTexCoordForEntryId(next_data_id, data); + const Vector2f p_uv = GetTexCoordForEntryId(prev_data_id, data); + if (p_uv == n_uv) { + // We cannot do a reliable prediction on degenerated UV triangles. + predicted_value_[0] = static_cast<int>(p_uv[0]); + predicted_value_[1] = static_cast<int>(p_uv[1]); + return; + } + + // Get positions at all corners. + const Vector3f tip_pos = GetPositionForEntryId(data_id); + const Vector3f next_pos = GetPositionForEntryId(next_data_id); + const Vector3f prev_pos = GetPositionForEntryId(prev_data_id); + // Use the positions of the above triangle to predict the texture coordinate + // on the tip corner C. + // Convert the triangle into a new coordinate system defined by orthogonal + // bases vectors S, T, where S is vector prev_pos - next_pos and T is an + // perpendicular vector to S in the same plane as vector the + // tip_pos - next_pos. + // The transformed triangle in the new coordinate system is then going to + // be represented as: + // + // 1 ^ + // | + // | + // | C + // | / \ + // | / \ + // |/ \ + // N--------------P + // 0 1 + // + // Where next_pos point (N) is at position (0, 0), prev_pos point (P) is + // at (1, 0). Our goal is to compute the position of the tip_pos point (C) + // in this new coordinate space (s, t). + // + const Vector3f pn = prev_pos - next_pos; + const Vector3f cn = tip_pos - next_pos; + const float pn_norm2_squared = pn.SquaredNorm(); + // Coordinate s of the tip corner C is simply the dot product of the + // normalized vectors |pn| and |cn| (normalized by the length of |pn|). + // Since both of these vectors are normalized, we don't need to perform the + // normalization explicitly and instead we can just use the squared norm + // of |pn| as a denominator of the resulting dot product of non normalized + // vectors. + float s, t; + // |pn_norm2_squared| can be exactly 0 when the next_pos and prev_pos are + // the same positions (e.g. because they were quantized to the same + // location). + if (pn_norm2_squared > 0) { + s = pn.Dot(cn) / pn_norm2_squared; + // To get the coordinate t, we can use formula: + // t = |C-N - (P-N) * s| / |P-N| + // Do not use std::sqrt to avoid changes in the bitstream. + t = sqrt((cn - pn * s).SquaredNorm() / pn_norm2_squared); + } else { + s = 0; + t = 0; + } + + // Now we need to transform the point (s, t) to the texture coordinate space + // UV. We know the UV coordinates on points N and P (N_UV and P_UV). Lets + // denote P_UV - N_UV = PN_UV. PN_UV is then 2 dimensional vector that can + // be used to define transformation from the normalized coordinate system + // to the texture coordinate system using a 3x3 affine matrix M: + // + // M = | PN_UV[0] -PN_UV[1] N_UV[0] | + // | PN_UV[1] PN_UV[0] N_UV[1] | + // | 0 0 1 | + // + // The predicted point C_UV in the texture space is then equal to + // C_UV = M * (s, t, 1). Because the triangle in UV space may be flipped + // around the PN_UV axis, we also need to consider point C_UV' = M * (s, -t) + // as the prediction. + const Vector2f pn_uv = p_uv - n_uv; + const float pnus = pn_uv[0] * s + n_uv[0]; + const float pnut = pn_uv[0] * t; + const float pnvs = pn_uv[1] * s + n_uv[1]; + const float pnvt = pn_uv[1] * t; + Vector2f predicted_uv; + + // When encoding compute both possible vectors and determine which one + // results in a better prediction. + const Vector2f predicted_uv_0(pnus - pnvt, pnvs + pnut); + const Vector2f predicted_uv_1(pnus + pnvt, pnvs - pnut); + const Vector2f c_uv = GetTexCoordForEntryId(data_id, data); + if ((c_uv - predicted_uv_0).SquaredNorm() < + (c_uv - predicted_uv_1).SquaredNorm()) { + predicted_uv = predicted_uv_0; + orientations_.push_back(true); + } else { + predicted_uv = predicted_uv_1; + orientations_.push_back(false); + } + if (std::is_integral<DataTypeT>::value) { + // Round the predicted value for integer types. + predicted_value_[0] = static_cast<int>(floor(predicted_uv[0] + 0.5)); + predicted_value_[1] = static_cast<int>(floor(predicted_uv[1] + 0.5)); + } else { + predicted_value_[0] = static_cast<int>(predicted_uv[0]); + predicted_value_[1] = static_cast<int>(predicted_uv[1]); + } + return; + } + // Else we don't have available textures on both corners. For such case we + // can't use positions for predicting the uv value and we resort to delta + // coding. + int data_offset = 0; + if (prev_data_id < data_id) { + // Use the value on the previous corner as the prediction. + data_offset = prev_data_id * num_components_; + } + if (next_data_id < data_id) { + // Use the value on the next corner as the prediction. + data_offset = next_data_id * num_components_; + } else { + // None of the other corners have a valid value. Use the last encoded value + // as the prediction if possible. + if (data_id > 0) { + data_offset = (data_id - 1) * num_components_; + } else { + // We are encoding the first value. Predict 0. + for (int i = 0; i < num_components_; ++i) { + predicted_value_[i] = 0; + } + return; + } + } + for (int i = 0; i < num_components_; ++i) { + predicted_value_[i] = data[data_offset + i]; + } +} + +} // namespace draco + +#endif // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_MESH_PREDICTION_SCHEME_TEX_COORDS_H_ |