| // Copyright 2013 The Flutter Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #pragma once |
| |
| #include <functional> |
| #include <memory> |
| #include <vector> |
| |
| #include "flutter/fml/macros.h" |
| #include "impeller/geometry/path.h" |
| #include "impeller/geometry/point.h" |
| |
| struct TESStesselator; |
| |
| namespace impeller { |
| |
| void DestroyTessellator(TESStesselator* tessellator); |
| |
| using CTessellator = |
| std::unique_ptr<TESStesselator, decltype(&DestroyTessellator)>; |
| |
| enum class WindingOrder { |
| kClockwise, |
| kCounterClockwise, |
| }; |
| |
| //------------------------------------------------------------------------------ |
| /// @brief A utility that generates triangles of the specified fill type |
| /// given a polyline. This happens on the CPU. |
| /// |
| /// This object is not thread safe, and its methods must not be |
| /// called from multiple threads. |
| /// |
| class Tessellator { |
| public: |
| enum class Result { |
| kSuccess, |
| kInputError, |
| kTessellationError, |
| }; |
| |
| Tessellator(); |
| |
| ~Tessellator(); |
| |
| /// @brief An arbitrary value to determine when a multi-contour non-zero fill |
| /// path should be split into multiple tessellations. |
| static constexpr size_t kMultiContourThreshold = 30u; |
| |
| /// @brief A callback that returns the results of the tessellation. |
| /// |
| /// The index buffer may not be populated, in which case [indices] will |
| /// be nullptr and indices_count will be 0. |
| using BuilderCallback = std::function<bool(const float* vertices, |
| size_t vertices_count, |
| const uint16_t* indices, |
| size_t indices_count)>; |
| |
| //---------------------------------------------------------------------------- |
| /// @brief Generates filled triangles from the path. A callback is |
| /// invoked once for the entire tessellation. |
| /// |
| /// @param[in] path The path to tessellate. |
| /// @param[in] tolerance The tolerance value for conversion of the path to |
| /// a polyline. This value is often derived from the |
| /// Matrix::GetMaxBasisLength of the CTM applied to the |
| /// path for rendering. |
| /// @param[in] callback The callback, return false to indicate failure. |
| /// |
| /// @return The result status of the tessellation. |
| /// |
| Tessellator::Result Tessellate(const Path& path, |
| Scalar tolerance, |
| const BuilderCallback& callback); |
| |
| //---------------------------------------------------------------------------- |
| /// @brief Given a convex path, create a triangle fan structure. |
| /// |
| /// @param[in] path The path to tessellate. |
| /// @param[in] tolerance The tolerance value for conversion of the path to |
| /// a polyline. This value is often derived from the |
| /// Matrix::GetMaxBasisLength of the CTM applied to the |
| /// path for rendering. |
| /// |
| /// @return A point vector containing the vertices and a vector of indices |
| /// into the point vector. |
| /// |
| std::pair<std::vector<Point>, std::vector<uint16_t>> TessellateConvex( |
| const Path& path, |
| Scalar tolerance); |
| |
| private: |
| /// Used for polyline generation. |
| std::unique_ptr<std::vector<Point>> point_buffer_; |
| CTessellator c_tessellator_; |
| |
| Tessellator(const Tessellator&) = delete; |
| |
| Tessellator& operator=(const Tessellator&) = delete; |
| }; |
| |
| } // namespace impeller |