Flutter Impeller
impeller::ClipContents Class Reference

#include <clip_contents.h>

Public Member Functions

 ClipContents (Rect coverage_rect, bool is_axis_aligned_rect)
 
 ~ClipContents ()
 
void SetGeometry (GeometryResult geometry)
 Set the pre-tessellated clip geometry. More...
 
void SetClipOperation (Entity::ClipOperation clip_op)
 
ClipCoverage GetClipCoverage (const std::optional< Rect > &current_clip_coverage) const
 Given the current pass space bounding rectangle of the clip buffer, return the expected clip coverage after this draw call. This should only be implemented for contents that may write to the clip buffer. More...
 
bool Render (const ContentContext &renderer, RenderPass &pass, uint32_t clip_depth) const
 

Detailed Description

Definition at line 29 of file clip_contents.h.

Constructor & Destructor Documentation

◆ ClipContents()

impeller::ClipContents::ClipContents ( Rect  coverage_rect,
bool  is_axis_aligned_rect 
)

Definition at line 31 of file clip_contents.cc.

32  : coverage_rect_(coverage_rect),
33  is_axis_aligned_rect_(is_axis_aligned_rect) {}

◆ ~ClipContents()

impeller::ClipContents::~ClipContents ( )
default

Member Function Documentation

◆ GetClipCoverage()

ClipCoverage impeller::ClipContents::GetClipCoverage ( const std::optional< Rect > &  current_clip_coverage) const

Given the current pass space bounding rectangle of the clip buffer, return the expected clip coverage after this draw call. This should only be implemented for contents that may write to the clip buffer.

During rendering, coverage coordinates count pixels from the top left corner of the framebuffer.

Definition at line 45 of file clip_contents.cc.

46  {
47  if (!current_clip_coverage.has_value()) {
48  return ClipCoverage{.coverage = std::nullopt};
49  }
50  switch (clip_op_) {
52  // This can be optimized further by considering cases when the bounds of
53  // the current stencil will shrink.
54  return {
55  .is_difference_or_non_square = true, //
56  .coverage = current_clip_coverage //
57  };
59  if (coverage_rect_.IsEmpty() || !current_clip_coverage.has_value()) {
60  return ClipCoverage{.coverage = std::nullopt};
61  }
62  return {
63  .is_difference_or_non_square = !is_axis_aligned_rect_, //
64  .coverage = current_clip_coverage->Intersection(coverage_rect_), //
65  };
66  }
67  FML_UNREACHABLE();
68 }
constexpr bool IsEmpty() const
Returns true if either of the width or height are 0, negative, or NaN.
Definition: rect.h:301

References impeller::ClipCoverage::coverage, impeller::TRect< T >::IsEmpty(), impeller::Entity::kDifference, and impeller::Entity::kIntersect.

Referenced by impeller::EntityPassClipStack::RecordClip().

◆ Render()

bool impeller::ClipContents::Render ( const ContentContext renderer,
RenderPass pass,
uint32_t  clip_depth 
) const

Stencil preparation draw.

Write depth.

Definition at line 70 of file clip_contents.cc.

72  {
73  if (!clip_geometry_.vertex_buffer) {
74  return true;
75  }
76 
78 
79  VS::FrameInfo info;
80  info.depth = GetShaderClipDepth(clip_depth);
81 
82  auto options = OptionsFromPass(pass);
83  options.blend_mode = BlendMode::kDst;
84 
85  pass.SetStencilReference(0);
86 
87  /// Stencil preparation draw.
88 
89  options.depth_write_enabled = false;
90  options.primitive_type = clip_geometry_.type;
91  pass.SetVertexBuffer(clip_geometry_.vertex_buffer);
92  switch (clip_geometry_.mode) {
94  pass.SetCommandLabel("Clip stencil preparation (NonZero)");
95  options.stencil_mode =
97  break;
99  pass.SetCommandLabel("Clip stencil preparation (EvenOdd)");
100  options.stencil_mode =
102  break;
105  pass.SetCommandLabel("Clip stencil preparation (Increment)");
106  options.stencil_mode =
108  break;
109  }
110  pass.SetPipeline(renderer.GetClipPipeline(options));
111 
112  info.mvp = clip_geometry_.transform;
113  VS::BindFrameInfo(pass, renderer.GetTransientsBuffer().EmplaceUniform(info));
114 
115  if (!pass.Draw().ok()) {
116  return false;
117  }
118 
119  /// Write depth.
120 
121  options.depth_write_enabled = true;
122  options.primitive_type = PrimitiveType::kTriangleStrip;
123  Rect cover_area;
124  switch (clip_op_) {
126  pass.SetCommandLabel("Intersect Clip");
127  options.stencil_mode =
129  cover_area = Rect::MakeSize(pass.GetRenderTargetSize());
130  break;
132  pass.SetCommandLabel("Difference Clip");
134  cover_area = coverage_rect_;
135  break;
136  }
137  auto points = cover_area.GetPoints();
138  pass.SetVertexBuffer(
139  CreateVertexBuffer(points, renderer.GetTransientsBuffer()));
140 
141  pass.SetPipeline(renderer.GetClipPipeline(options));
142 
143  info.mvp = pass.GetOrthographicTransform();
144  VS::BindFrameInfo(pass, renderer.GetTransientsBuffer().EmplaceUniform(info));
145 
146  return pass.Draw().ok();
147 }
static Scalar GetShaderClipDepth(uint32_t clip_depth)
TRect< Scalar > Rect
Definition: rect.h:792
VertexBuffer CreateVertexBuffer(std::array< VertexType, size > input, HostBuffer &host_buffer)
Create an index-less vertex buffer from a fixed size array.
LinePipeline::VertexShader VS
ContentContextOptions OptionsFromPass(const RenderPass &pass)
Definition: contents.cc:19
PrimitiveType type
Definition: geometry.h:37
@ kNormal
The geometry has no overlapping triangles.
VertexBuffer vertex_buffer
Definition: geometry.h:38
constexpr static TRect MakeSize(const TSize< U > &size)
Definition: rect.h:150
std::vector< Point > points

References impeller::CreateVertexBuffer(), impeller::RenderPass::Draw(), impeller::HostBuffer::EmplaceUniform(), impeller::ContentContext::GetClipPipeline(), impeller::RenderPass::GetOrthographicTransform(), impeller::TRect< T >::GetPoints(), impeller::RenderPass::GetRenderTargetSize(), impeller::GetShaderClipDepth(), impeller::ContentContext::GetTransientsBuffer(), impeller::ContentContextOptions::kCoverCompare, impeller::ContentContextOptions::kCoverCompareInverted, impeller::Entity::kDifference, impeller::kDst, impeller::GeometryResult::kEvenOdd, impeller::Entity::kIntersect, impeller::GeometryResult::kNonZero, impeller::GeometryResult::kNormal, impeller::ContentContextOptions::kOverdrawPreventionIncrement, impeller::GeometryResult::kPreventOverdraw, impeller::ContentContextOptions::kStencilEvenOddFill, impeller::ContentContextOptions::kStencilNonZeroFill, impeller::kTriangleStrip, impeller::TRect< Scalar >::MakeSize(), impeller::GeometryResult::mode, impeller::OptionsFromPass(), points, impeller::RenderPass::SetCommandLabel(), impeller::RenderPass::SetPipeline(), impeller::RenderPass::SetStencilReference(), impeller::RenderPass::SetVertexBuffer(), impeller::GeometryResult::transform, impeller::GeometryResult::type, and impeller::GeometryResult::vertex_buffer.

Referenced by impeller::Canvas::ClipGeometry().

◆ SetClipOperation()

void impeller::ClipContents::SetClipOperation ( Entity::ClipOperation  clip_op)

Definition at line 41 of file clip_contents.cc.

41  {
42  clip_op_ = clip_op;
43 }

Referenced by impeller::Canvas::ClipGeometry().

◆ SetGeometry()

void impeller::ClipContents::SetGeometry ( GeometryResult  geometry)

Set the pre-tessellated clip geometry.

Definition at line 37 of file clip_contents.cc.

37  {
38  clip_geometry_ = std::move(clip_geometry);
39 }

Referenced by impeller::Canvas::ClipGeometry().


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