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[Impeller] Implement draw order optimization. (#54067)
For each clip scope, draw opaque items in reverse order and translucent/backdrop-independent items in their original order afterwards. Clips are treated as translucent by the parent scope. Respects clips, subpass collapse, and the clear color optimization.
1 parent ebe517b commit 1df62d3

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+495
-35
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‎ci/licenses_golden/excluded_files

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@@ -164,6 +164,7 @@
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../../../flutter/impeller/entity/contents/host_buffer_unittests.cc
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../../../flutter/impeller/entity/contents/test
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../../../flutter/impeller/entity/contents/tiled_texture_contents_unittests.cc
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../../../flutter/impeller/entity/draw_order_resolver_unittests.cc
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../../../flutter/impeller/entity/entity_pass_target_unittests.cc
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../../../flutter/impeller/entity/entity_pass_unittests.cc
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../../../flutter/impeller/entity/entity_unittests.cc

‎ci/licenses_golden/licenses_flutter

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@@ -42130,6 +42130,8 @@ ORIGIN: ../../../flutter/impeller/entity/contents/tiled_texture_contents.cc + ..
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ORIGIN: ../../../flutter/impeller/entity/contents/tiled_texture_contents.h + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/contents/vertices_contents.cc + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/contents/vertices_contents.h + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/draw_order_resolver.cc + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/draw_order_resolver.h + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/entity.cc + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/entity.h + ../../../flutter/LICENSE
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ORIGIN: ../../../flutter/impeller/entity/entity_pass.cc + ../../../flutter/LICENSE
@@ -45015,6 +45017,8 @@ FILE: ../../../flutter/impeller/entity/contents/tiled_texture_contents.cc
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FILE: ../../../flutter/impeller/entity/contents/tiled_texture_contents.h
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FILE: ../../../flutter/impeller/entity/contents/vertices_contents.cc
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FILE: ../../../flutter/impeller/entity/contents/vertices_contents.h
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FILE: ../../../flutter/impeller/entity/draw_order_resolver.cc
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FILE: ../../../flutter/impeller/entity/draw_order_resolver.h
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FILE: ../../../flutter/impeller/entity/entity.cc
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FILE: ../../../flutter/impeller/entity/entity.h
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FILE: ../../../flutter/impeller/entity/entity_pass.cc

‎impeller/entity/BUILD.gn

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@@ -166,6 +166,8 @@ impeller_component("entity") {
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"contents/tiled_texture_contents.h",
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"contents/vertices_contents.cc",
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"contents/vertices_contents.h",
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"draw_order_resolver.cc",
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"draw_order_resolver.h",
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"entity.cc",
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"entity.h",
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"entity_pass.cc",
@@ -248,6 +250,7 @@ impeller_component("entity_unittests") {
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"contents/filters/matrix_filter_contents_unittests.cc",
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"contents/host_buffer_unittests.cc",
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"contents/tiled_texture_contents_unittests.cc",
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"draw_order_resolver_unittests.cc",
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"entity_pass_target_unittests.cc",
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"entity_pass_unittests.cc",
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"entity_playground.cc",

‎impeller/entity/contents/color_source_contents.h

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@@ -213,6 +213,11 @@ class ColorSourceContents : public Contents {
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pass.SetVertexBuffer(std::move(geometry_result.vertex_buffer));
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options.primitive_type = geometry_result.type;
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// Enable depth writing for all opaque entities in order to allow
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// reordering. Opaque entities are coerced to source blending by
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// `EntityPass::AddEntity`.
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options.depth_write_enabled = options.blend_mode == BlendMode::kSource;
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// Take the pre-populated vertex shader uniform struct and set managed
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// values.
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frame_info.mvp = geometry_result.transform;

‎impeller/entity/contents/filters/gaussian_blur_filter_contents.cc

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@@ -555,16 +555,16 @@ Entity ApplyBlurStyle(FilterContents::BlurStyle blur_style,
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const ContentContext& renderer, const Entity& entity,
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RenderPass& pass) mutable {
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bool result = true;
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blur_entity.SetClipDepth(entity.GetClipDepth());
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blur_entity.SetTransform(entity.GetTransform() *
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blurred_transform);
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result = result && blur_entity.Render(renderer, pass);
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snapshot_entity.SetTransform(
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entity.GetTransform() *
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Matrix::MakeScale(1.f / source_space_scalar) *
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snapshot_transform);
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snapshot_entity.SetClipDepth(entity.GetClipDepth());
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result = result && snapshot_entity.Render(renderer, pass);
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blur_entity.SetClipDepth(entity.GetClipDepth());
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blur_entity.SetTransform(entity.GetTransform() *
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blurred_transform);
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result = result && blur_entity.Render(renderer, pass);
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return result;
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}),
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fml::MakeCopyable([blur_entity = blur_entity.Clone(),

‎impeller/entity/contents/texture_contents.cc

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@@ -153,6 +153,9 @@ bool TextureContents::Render(const ContentContext& renderer,
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}
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pipeline_options.primitive_type = PrimitiveType::kTriangleStrip;
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pipeline_options.depth_write_enabled =
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stencil_enabled_ && pipeline_options.blend_mode == BlendMode::kSource;
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pass.SetPipeline(strict_source_rect_enabled_
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? renderer.GetTextureStrictSrcPipeline(pipeline_options)
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: renderer.GetTexturePipeline(pipeline_options));

‎impeller/entity/draw_order_resolver.cc

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// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "impeller/entity/draw_order_resolver.h"
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#include "flutter/fml/logging.h"
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#include "impeller/base/validation.h"
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namespace impeller {
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DrawOrderResolver::DrawOrderResolver() : draw_order_layers_({{}}){};
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void DrawOrderResolver::AddElement(size_t element_index, bool is_opaque) {
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DrawOrderLayer& layer = draw_order_layers_.back();
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if (is_opaque) {
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layer.opaque_elements.push_back(element_index);
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} else {
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layer.dependent_elements.push_back(element_index);
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}
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}
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void DrawOrderResolver::PushClip(size_t element_index) {
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draw_order_layers_.back().dependent_elements.push_back(element_index);
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draw_order_layers_.push_back({});
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};
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void DrawOrderResolver::PopClip() {
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if (draw_order_layers_.size() == 1u) {
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// This is likely recoverable, so don't assert.
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VALIDATION_LOG
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<< "Attemped to pop the first draw order clip layer. This is a bug in "
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"`EntityPass`.";
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return;
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}
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DrawOrderLayer& layer = draw_order_layers_.back();
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DrawOrderLayer& parent_layer =
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draw_order_layers_[draw_order_layers_.size() - 2];
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layer.WriteCombinedDraws(parent_layer.dependent_elements, 0, 0);
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draw_order_layers_.pop_back();
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}
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void DrawOrderResolver::Flush() {
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FML_DCHECK(draw_order_layers_.size() >= 1u);
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size_t layer_count = draw_order_layers_.size();
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// Pop all clip layers.
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while (draw_order_layers_.size() > 1u) {
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PopClip();
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}
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// Move the root layer items into the sorted list.
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DrawOrderLayer& layer = draw_order_layers_.back();
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if (!first_root_flush_.has_value()) {
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// Record the first flush.
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first_root_flush_ = std::move(layer);
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layer = {};
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} else {
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// Write subsequent flushes into the sorted root list.
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layer.WriteCombinedDraws(sorted_elements_, 0, 0);
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layer.opaque_elements.clear();
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layer.dependent_elements.clear();
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}
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// Refill with empty layers.
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draw_order_layers_.resize(layer_count);
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}
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DrawOrderResolver::ElementRefs DrawOrderResolver::GetSortedDraws(
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size_t opaque_skip_count,
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size_t translucent_skip_count) const {
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FML_DCHECK(draw_order_layers_.size() == 1u)
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<< "Attempted to get sorted draws before all clips were popped.";
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ElementRefs sorted_elements;
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sorted_elements.reserve(
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(first_root_flush_.has_value()
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? first_root_flush_->opaque_elements.size() +
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first_root_flush_->dependent_elements.size()
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: 0u) +
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sorted_elements_.size() +
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draw_order_layers_.back().opaque_elements.size() +
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draw_order_layers_.back().dependent_elements.size());
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// Write all flushed items.
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if (first_root_flush_.has_value()) {
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first_root_flush_->WriteCombinedDraws(sorted_elements, opaque_skip_count,
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translucent_skip_count);
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}
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sorted_elements.insert(sorted_elements.end(), sorted_elements_.begin(),
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sorted_elements_.end());
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// Write any remaining non-flushed items.
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draw_order_layers_.back().WriteCombinedDraws(
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sorted_elements, first_root_flush_.has_value() ? 0 : opaque_skip_count,
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first_root_flush_.has_value() ? 0 : translucent_skip_count);
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return sorted_elements;
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}
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void DrawOrderResolver::DrawOrderLayer::WriteCombinedDraws(
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ElementRefs& destination,
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size_t opaque_skip_count,
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size_t translucent_skip_count) const {
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FML_DCHECK(opaque_skip_count <= opaque_elements.size());
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FML_DCHECK(translucent_skip_count <= dependent_elements.size());
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destination.reserve(destination.size() + //
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opaque_elements.size() - opaque_skip_count + //
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dependent_elements.size() - translucent_skip_count);
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// Draw backdrop-independent elements in reverse order first.
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destination.insert(destination.end(), opaque_elements.rbegin(),
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opaque_elements.rend() - opaque_skip_count);
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// Then, draw backdrop-dependent elements in their original order.
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destination.insert(destination.end(),
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dependent_elements.begin() + translucent_skip_count,
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dependent_elements.end());
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}
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} // namespace impeller

‎impeller/entity/draw_order_resolver.h

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// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_IMPELLER_ENTITY_DRAW_ORDER_RESOLVER_H_
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#define FLUTTER_IMPELLER_ENTITY_DRAW_ORDER_RESOLVER_H_
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#include <optional>
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#include <vector>
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namespace impeller {
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/// Helper that records draw indices in painter's order and sorts the draws into
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/// an optimized order based on translucency and clips.
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class DrawOrderResolver {
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public:
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using ElementRefs = std::vector<size_t>;
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DrawOrderResolver();
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void AddElement(size_t element_index, bool is_opaque);
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void PushClip(size_t element_index);
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void PopClip();
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void Flush();
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//-------------------------------------------------------------------------
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/// @brief Returns the sorted draws for the current draw order layer.
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/// This should only be called after all recording has finished.
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///
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/// @param[in] opaque_skip_count The number of opaque elements to skip
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/// when appending the combined elements.
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/// This is used for the "clear color"
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/// optimization.
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/// @param[in] translucent_skip_count The number of translucent elements to
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/// skip when appending the combined
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/// elements. This is used for the
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/// "clear color" optimization.
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///
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ElementRefs GetSortedDraws(size_t opaque_skip_count,
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size_t translucent_skip_count) const;
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private:
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/// A data structure for collecting sorted draws for a given "draw order
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/// layer". Currently these layers just correspond to the local clip stack.
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struct DrawOrderLayer {
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/// The list of backdrop-independent elements (always just opaque). These
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/// are order independent, and so we render these elements in reverse
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/// painter's order so that they cull one another.
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ElementRefs opaque_elements;
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/// The list of backdrop-dependent elements with respect to this draw
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/// order layer. These elements are drawn after all of the independent
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/// elements.
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ElementRefs dependent_elements;
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//-----------------------------------------------------------------------
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/// @brief Appends the combined opaque and transparent elements into
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/// a final destination buffer.
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///
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/// @param[in] destination The buffer to append the combined
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/// elements to.
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/// @param[in] opaque_skip_count The number of opaque elements to
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/// skip when appending the combined
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/// elements. This is used for the
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/// "clear color" optimization.
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/// @param[in] translucent_skip_count The number of translucent elements
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/// to skip when appending the combined
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/// elements. This is used for the
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/// "clear color" optimization.
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///
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void WriteCombinedDraws(ElementRefs& destination,
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size_t opaque_skip_count,
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size_t translucent_skip_count) const;
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};
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std::vector<DrawOrderLayer> draw_order_layers_;
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// The first time the root layer is flushed, the layer contents are stored
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// here. This is done to enable element skipping for the clear color
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// optimization.
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std::optional<DrawOrderLayer> first_root_flush_;
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// All subsequent root flushes are stored here.
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ElementRefs sorted_elements_;
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DrawOrderResolver(const DrawOrderResolver&) = delete;
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DrawOrderResolver& operator=(const DrawOrderResolver&) = delete;
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};
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} // namespace impeller
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#endif // FLUTTER_IMPELLER_ENTITY_DRAW_ORDER_RESOLVER_H_

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