impeller::PointFieldGeometry Class Reference

#include <point_field_geometry.h>

Inheritance diagram for impeller::PointFieldGeometry:

Public Member Functions
	PointFieldGeometry (std::vector< Point > points, Scalar radius, bool round)
	~PointFieldGeometry ()=default
Public Member Functions inherited from impeller::Geometry
virtual GeometryResult::Mode	GetResultMode () const
virtual bool	CoversArea (const Matrix &transform, const Rect &rect) const
	Determines if this geometry, transformed by the given transform, will completely cover all surface area of the given rect.
virtual bool	IsAxisAlignedRect () const
virtual bool	CanApplyMaskFilter () const

Private Member Functions
GeometryResult	GetPositionBuffer (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
std::optional< Rect >	GetCoverage (const Matrix &transform) const override

Additional Inherited Members
Static Public Member Functions inherited from impeller::Geometry
static std::shared_ptr< Geometry >	MakeFillPath (const Path &path, std::optional< Rect > inner_rect=std::nullopt)
static std::shared_ptr< Geometry >	MakeStrokePath (const Path &path, Scalar stroke_width=0.0, Scalar miter_limit=4.0, Cap stroke_cap=Cap::kButt, Join stroke_join=Join::kMiter)
static std::shared_ptr< Geometry >	MakeCover ()
static std::shared_ptr< Geometry >	MakeRect (const Rect &rect)
static std::shared_ptr< Geometry >	MakeOval (const Rect &rect)
static std::shared_ptr< Geometry >	MakeLine (const Point &p0, const Point &p1, Scalar width, Cap cap)
static std::shared_ptr< Geometry >	MakeCircle (const Point &center, Scalar radius)
static std::shared_ptr< Geometry >	MakeStrokedCircle (const Point &center, Scalar radius, Scalar stroke_width)
static std::shared_ptr< Geometry >	MakeRoundRect (const Rect &rect, const Size &radii)
static std::shared_ptr< Geometry >	MakePointField (std::vector< Point > points, Scalar radius, bool round)
Static Protected Member Functions inherited from impeller::Geometry
static GeometryResult	ComputePositionGeometry (const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)

Detailed Description

Definition at line 12 of file point_field_geometry.h.

Constructor & Destructor Documentation

PointFieldGeometry()

impeller::PointFieldGeometry::PointFieldGeometry	(	std::vector< Point >	points,
		Scalar	radius,
		bool	round
	)

Definition at line 13 of file point_field_geometry.cc.

    : points_(std::move(points)), radius_(radius), round_(round) {}

~PointFieldGeometry()

impeller::PointFieldGeometry::~PointFieldGeometry ( )

default

Member Function Documentation

GetCoverage()

std::optional< Rect > impeller::PointFieldGeometry::GetCoverage ( const Matrix &  transform ) const

overrideprivatevirtual

Implements impeller::Geometry.

Definition at line 87 of file point_field_geometry.cc.

                                   {
  if (points_.size() > 0) {
    // Doesn't use MakePointBounds as this isn't resilient to points that
    // all lie along the same axis.
    auto first = points_.begin();
    auto last = points_.end();
    auto left = first->x;
    auto top = first->y;
    auto right = first->x;
    auto bottom = first->y;
    for (auto it = first + 1; it < last; ++it) {
      left = std::min(left, it->x);
      top = std::min(top, it->y);
      right = std::max(right, it->x);
      bottom = std::max(bottom, it->y);
    }
    auto coverage = Rect::MakeLTRB(left - radius_, top - radius_,
                                   right + radius_, bottom + radius_);
    return coverage.TransformBounds(transform);
  }
  return std::nullopt;
}

GetPositionBuffer()

GeometryResult impeller::PointFieldGeometry::GetPositionBuffer ( const ContentContext &  renderer, const Entity &  entity, RenderPass &  pass  ) const

overrideprivatevirtual

Implements impeller::Geometry.

Definition at line 18 of file point_field_geometry.cc.

                            {
  if (radius_ < 0.0) {
    return {};
  }
  Matrix transform = entity.GetTransform();
  Scalar determinant = transform.GetDeterminant();
  if (determinant == 0) {
    return {};
  }
 
  Scalar min_size = 1.0f / sqrt(std::abs(determinant));
  Scalar radius = std::max(radius_, min_size);
 
  HostBuffer& host_buffer = renderer.GetTransientsBuffer();
  VertexBufferBuilder<SolidFillVertexShader::PerVertexData> vtx_builder;
 
  if (round_) {
    // Get triangulation relative to {0, 0} so we can translate it to each
    // point in turn.
    auto generator =
        renderer.GetTessellator()->FilledCircle(transform, {}, radius);
    FML_DCHECK(generator.GetTriangleType() == PrimitiveType::kTriangleStrip);
    std::vector<Point> circle_vertices;
    circle_vertices.reserve(generator.GetVertexCount());
    generator.GenerateVertices([&circle_vertices](const Point& p) {  //
      circle_vertices.push_back(p);
    });
    FML_DCHECK(circle_vertices.size() == generator.GetVertexCount());
 
    vtx_builder.Reserve((circle_vertices.size() + 2) * points_.size() - 2);
    for (auto& center : points_) {
      if (vtx_builder.HasVertices()) {
        vtx_builder.AppendVertex(vtx_builder.Last());
        vtx_builder.AppendVertex({center + circle_vertices[0]});
      }
 
      for (auto& vertex : circle_vertices) {
        vtx_builder.AppendVertex({center + vertex});
      }
    }
  } else {
    vtx_builder.Reserve(6 * points_.size() - 2);
    for (auto& point : points_) {
      auto first = Point(point.x - radius, point.y - radius);
 
      if (vtx_builder.HasVertices()) {
        vtx_builder.AppendVertex(vtx_builder.Last());
        vtx_builder.AppendVertex({first});
      }
 
      // Z pattern from UL -> UR -> LL -> LR
      vtx_builder.AppendVertex({first});
      vtx_builder.AppendVertex({{point.x + radius, point.y - radius}});
      vtx_builder.AppendVertex({{point.x - radius, point.y + radius}});
      vtx_builder.AppendVertex({{point.x + radius, point.y + radius}});
    }
  }
 
  return GeometryResult{
      .type = PrimitiveType::kTriangleStrip,
      .vertex_buffer = vtx_builder.CreateVertexBuffer(host_buffer),
      .transform = entity.GetShaderTransform(pass),
  };
}

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The documentation for this class was generated from the following files:

• impeller/entity/geometry/point_field_geometry.h
• impeller/entity/geometry/point_field_geometry.cc