uber_sdf_parameters.h

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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_ENTITY_CONTENTS_UBER_SDF_PARAMETERS_H_
#define FLUTTER_IMPELLER_ENTITY_CONTENTS_UBER_SDF_PARAMETERS_H_
 
#include <optional>
 
#include "impeller/geometry/color.h"
#include "impeller/geometry/point.h"
#include "impeller/geometry/rect.h"
#include "impeller/geometry/round_rect.h"
#include "impeller/geometry/round_superellipse_param.h"
#include "impeller/geometry/stroke_parameters.h"
#include "impeller/geometry/vector.h"
 
namespace impeller {
 
/// Parameters for rendering shapes using the UberSDF shader.
struct UberSDFParameters {
  /// The amount by which the UberSDF shader fades the edge of the drawn shapes,
  /// in pixels.
  static constexpr Scalar kAntialiasPixels = 1.0f;
 
  /// The type of primitive shape.
  enum class Type {
    kCircle,
    kRect,
    kOval,
    kRoundedRect,
    kRoundedSuperellipseSymmetric,
  };
 
  /// Creates UberSDFParameters for a rectangle.
  static UberSDFParameters MakeRect(Color color,
                                    const Rect& rect,
                                    std::optional<StrokeParameters> stroke);
 
  /// Creates UberSDFParameters for a circle.
  static UberSDFParameters MakeCircle(Color color,
                                      const Point& center,
                                      Scalar radius,
                                      std::optional<StrokeParameters> stroke);
 
  /// Creates UberSDFParameters for an Oval.
  static UberSDFParameters MakeOval(Color color,
                                    const Rect& bounds,
                                    std::optional<StrokeParameters> stroke);
 
  /// Creates UberSDFParameters for a rounded rectangle.
  static UberSDFParameters MakeRoundedRect(
      Color color,
      const Rect& rect,
      const RoundingRadii& radii,
      std::optional<StrokeParameters> stroke);
 
  /// Creates UberSDFParameters for an asymmetric round superellipse.
  static UberSDFParameters MakeRoundedSuperellipse(
      Color color,
      const Rect& bounds,
      const RoundSuperellipseParam& round_superellipse_params,
      std::optional<StrokeParameters> stroke);
 
  /// The type of shape to render.
  Type type;
 
  /// The color used for filling or stroking the shape.
  Color color;
 
  /// The center point of the shape in local coordinates.
  Point center;
 
  /// For a rectangle, this is half the width and height.
  /// For a circle, this is the radius in both dimensions.
  /// For an oval, this is half the width and height of the bounds.
  Point size;
 
  /// The stroke parameters. If std::nullopt, the shape is filled.
  std::optional<StrokeParameters> stroke;
 
  /// The degree (n) of the superellipse curve for the top and right octants.
  Point superellipse_degree;
 
  /// The semi-axis length of the superellipse curve for the top and right
  /// octants.
  Point superellipse_semi_axis;
 
  /// The angular span of the circular cap for the top and right octants.
  Point angle_span;
 
  /// The geometric offset 'c' used to connect the two octants of each quadrant.
  float octant_offset_c;
 
  /// The circular cap center for the top octant of each
  /// quadrant.
  Point circle_center_top;
 
  /// The circular cap center for the right octant of each
  /// quadrant.
  Point circle_center_right;
 
  /// The scaling factors used to transform normalized superellipses to their
  /// true size.
  Point superellipse_scale;
 
  /// Rounding radii for standard rounded rects and corner radii for circular
  /// caps of superellipses for top and right octants.
  Vector4 radii;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_ENTITY_CONTENTS_UBER_SDF_PARAMETERS_H_