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// 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.
#ifndef FLUTTER_IMPELLER_RENDERER_COMPUTE_TESSELLATOR_H_
#define FLUTTER_IMPELLER_RENDERER_COMPUTE_TESSELLATOR_H_
#include "flutter/fml/macros.h"
#include "impeller/core/buffer_view.h"
#include "impeller/geometry/path.h"
#include "impeller/renderer/command_buffer.h"
#include "impeller/renderer/context.h"
namespace impeller {
//------------------------------------------------------------------------------
/// @brief A utility that generates triangles of the specified fill type
/// given a path.
///
class ComputeTessellator {
public:
ComputeTessellator();
~ComputeTessellator();
static constexpr size_t kMaxCubicCount = 512;
static constexpr size_t kMaxQuadCount = 2048;
static constexpr size_t kMaxLineCount = 4096;
static constexpr size_t kMaxComponentCount =
kMaxCubicCount + kMaxQuadCount + kMaxLineCount;
enum class Status {
kCommandInvalid,
kTooManyComponents,
kOk,
};
enum class Style {
kStroke,
// TODO(dnfield): Implement kFill.
};
ComputeTessellator& SetStyle(Style value);
ComputeTessellator& SetStrokeWidth(Scalar value);
ComputeTessellator& SetStrokeJoin(Join value);
ComputeTessellator& SetStrokeCap(Cap value);
ComputeTessellator& SetMiterLimit(Scalar value);
ComputeTessellator& SetCubicAccuracy(Scalar value);
ComputeTessellator& SetQuadraticTolerance(Scalar value);
//----------------------------------------------------------------------------
/// @brief Generates triangles from the path.
/// If the data needs to be synchronized back to the CPU, e.g.
/// because one of the buffer views are host visible and will be
/// used without creating a blit pass to copy them back, the
/// callback is used to determine when the GPU calculation is
/// complete and its status.
/// On Metal, no additional synchronization is needed as long as
/// the buffers are not heap allocated, so no additional
/// synchronization mechanism is provided.
///
/// @return A |Status| value indicating success or failure of the submission.
///
// TODO(dnfield): Provide additional synchronization methods here for Vulkan
// and heap allocated buffers on Metal.
Status Tessellate(
const Path& path,
HostBuffer& host_buffer,
const std::shared_ptr<Context>& context,
BufferView vertex_buffer,
BufferView vertex_buffer_count,
const CommandBuffer::CompletionCallback& callback = nullptr) const;
private:
Style style_ = Style::kStroke;
Scalar stroke_width_ = 1.0f;
Cap stroke_cap_ = Cap::kButt;
Join stroke_join_ = Join::kMiter;
Scalar miter_limit_ = 4.0f;
Scalar cubic_accuracy_ = kDefaultCurveTolerance;
Scalar quad_tolerance_ = .1f;
ComputeTessellator(const ComputeTessellator&) = delete;
ComputeTessellator& operator=(const ComputeTessellator&) = delete;
};
} // namespace impeller
#endif // FLUTTER_IMPELLER_RENDERER_COMPUTE_TESSELLATOR_H_