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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "BSPTree.h"
#include "mozilla/gfx/Polygon.h"
namespace mozilla {
namespace layers {
LayerPolygon PopFront(std::deque<LayerPolygon>& aLayers)
{
LayerPolygon layer = Move(aLayers.front());
aLayers.pop_front();
return layer;
}
void
BSPTree::BuildDrawOrder(const UniquePtr<BSPTreeNode>& aNode,
nsTArray<LayerPolygon>& aLayers) const
{
const gfx::Point3D& normal = aNode->First().GetNormal();
UniquePtr<BSPTreeNode> *front = &aNode->front;
UniquePtr<BSPTreeNode> *back = &aNode->back;
// Since the goal is to return the draw order from back to front, we reverse
// the traversal order if the current polygon is facing towards the camera.
const bool reverseOrder = normal.z > 0.0f;
if (reverseOrder) {
std::swap(front, back);
}
if (*front) {
BuildDrawOrder(*front, aLayers);
}
for (LayerPolygon& layer : aNode->layers) {
MOZ_ASSERT(layer.geometry);
if (layer.geometry->GetPoints().Length() >= 3) {
aLayers.AppendElement(Move(layer));
}
}
if (*back) {
BuildDrawOrder(*back, aLayers);
}
}
void
BSPTree::BuildTree(UniquePtr<BSPTreeNode>& aRoot,
std::deque<LayerPolygon>& aLayers)
{
if (aLayers.empty()) {
return;
}
const gfx::Polygon3D& plane = aRoot->First();
std::deque<LayerPolygon> backLayers, frontLayers;
for (LayerPolygon& layerPolygon : aLayers) {
const Maybe<gfx::Polygon3D>& geometry = layerPolygon.geometry;
size_t pos = 0, neg = 0;
nsTArray<float> dots = geometry->CalculateDotProducts(plane, pos, neg);
// Back polygon
if (pos == 0 && neg > 0) {
backLayers.push_back(Move(layerPolygon));
}
// Front polygon
else if (pos > 0 && neg == 0) {
frontLayers.push_back(Move(layerPolygon));
}
// Coplanar polygon
else if (pos == 0 && neg == 0) {
aRoot->layers.push_back(Move(layerPolygon));
}
// Polygon intersects with the splitting plane.
else if (pos > 0 && neg > 0) {
nsTArray<gfx::Point3D> backPoints, frontPoints;
geometry->SplitPolygon(plane, dots, backPoints, frontPoints);
const gfx::Point3D& normal = geometry->GetNormal();
Layer *layer = layerPolygon.layer;
backLayers.push_back(LayerPolygon(layer, Move(backPoints), normal));
frontLayers.push_back(LayerPolygon(layer, Move(frontPoints), normal));
}
}
if (!backLayers.empty()) {
aRoot->back.reset(new BSPTreeNode(PopFront(backLayers)));
BuildTree(aRoot->back, backLayers);
}
if (!frontLayers.empty()) {
aRoot->front.reset(new BSPTreeNode(PopFront(frontLayers)));
BuildTree(aRoot->front, frontLayers);
}
}
} // namespace layers
} // namespace mozilla
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