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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_VIZ_SERVICE_DISPLAY_BSP_TREE_H_
#define COMPONENTS_VIZ_SERVICE_DISPLAY_BSP_TREE_H_
#include <stddef.h>
#include <algorithm>
#include <memory>
#include <vector>
#include "base/containers/circular_deque.h"
#include "components/viz/service/display/bsp_compare_result.h"
#include "components/viz/service/display/draw_polygon.h"
#include "components/viz/service/viz_service_export.h"
namespace viz {
struct BspNode {
// This represents the splitting plane.
std::unique_ptr<DrawPolygon> node_data;
// This represents any coplanar geometry we found while building the BSP.
std::vector<std::unique_ptr<DrawPolygon>> coplanars_front;
std::vector<std::unique_ptr<DrawPolygon>> coplanars_back;
std::unique_ptr<BspNode> back_child;
std::unique_ptr<BspNode> front_child;
explicit BspNode(std::unique_ptr<DrawPolygon> data);
~BspNode();
};
class VIZ_SERVICE_EXPORT BspTree {
public:
explicit BspTree(base::circular_deque<std::unique_ptr<DrawPolygon>>* list);
std::unique_ptr<BspNode>& root() { return root_; }
template <typename ActionHandlerType>
void TraverseWithActionHandler(ActionHandlerType* action_handler) const {
if (root_) {
WalkInOrderRecursion<ActionHandlerType>(action_handler, root_.get());
}
}
~BspTree();
private:
std::unique_ptr<BspNode> root_;
void FromList(std::vector<std::unique_ptr<DrawPolygon>>* list);
void BuildTree(BspNode* node,
base::circular_deque<std::unique_ptr<DrawPolygon>>* data);
template <typename ActionHandlerType>
void WalkInOrderAction(ActionHandlerType* action_handler,
DrawPolygon* item) const {
(*action_handler)(item);
}
static bool OrderIndexLess(const std::unique_ptr<DrawPolygon>& x,
const std::unique_ptr<DrawPolygon>& y) {
return x->order_index() < y->order_index();
}
template <typename ActionHandlerType>
void WalkInOrderVisitNodes(
ActionHandlerType* action_handler,
const BspNode* node,
const BspNode* first_child,
const BspNode* second_child,
const std::vector<std::unique_ptr<DrawPolygon>>& first_coplanars,
const std::vector<std::unique_ptr<DrawPolygon>>& second_coplanars) const {
if (first_child) {
WalkInOrderRecursion(action_handler, first_child);
}
DCHECK(std::is_sorted(first_coplanars.begin(), first_coplanars.end(),
OrderIndexLess));
for (size_t i = 0; i < first_coplanars.size(); i++) {
WalkInOrderAction(action_handler, first_coplanars[i].get());
}
WalkInOrderAction(action_handler, node->node_data.get());
DCHECK(std::is_sorted(second_coplanars.begin(), second_coplanars.end(),
OrderIndexLess));
for (size_t i = 0; i < second_coplanars.size(); i++) {
WalkInOrderAction(action_handler, second_coplanars[i].get());
}
if (second_child) {
WalkInOrderRecursion(action_handler, second_child);
}
}
template <typename ActionHandlerType>
void WalkInOrderRecursion(ActionHandlerType* action_handler,
const BspNode* node) const {
// If our view is in front of the the polygon in this node then walk
// back then front; otherwise the reverse. However, for coplanars,
// the painting order rules in css-transforms consider only paint
// order (and not what is back/front facing) when determining how to
// paint coplanar planes.
if (GetCameraPositionRelative(*(node->node_data)) == BSP_FRONT) {
WalkInOrderVisitNodes<ActionHandlerType>(
action_handler, node, node->back_child.get(), node->front_child.get(),
node->coplanars_back, node->coplanars_front);
} else {
WalkInOrderVisitNodes<ActionHandlerType>(
action_handler, node, node->front_child.get(), node->back_child.get(),
node->coplanars_back, node->coplanars_front);
}
}
// Returns whether or not our viewer is in front of or behind the plane
// defined by this polygon/node
static BspCompareResult GetCameraPositionRelative(const DrawPolygon& node);
};
} // namespace viz
#endif // COMPONENTS_VIZ_SERVICE_DISPLAY_BSP_TREE_H_
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