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-rw-r--r--gfx/layers/BSPTree.cpp133
1 files changed, 133 insertions, 0 deletions
diff --git a/gfx/layers/BSPTree.cpp b/gfx/layers/BSPTree.cpp
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+++ b/gfx/layers/BSPTree.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 {
+
+class nsDisplayTransform;
+
+namespace layers {
+
+template <typename T>
+void BSPTree<T>::BuildDrawOrder(BSPTreeNode<T>* aNode,
+ nsTArray<BSPPolygon<T>>& aLayers) const {
+ const gfx::Point4D& normal = aNode->First().GetNormal();
+
+ BSPTreeNode<T>* front = aNode->front;
+ BSPTreeNode<T>* 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 (BSPPolygon<T>& layer : aNode->layers) {
+ MOZ_ASSERT(layer.geometry);
+
+ if (layer.geometry->GetPoints().Length() >= 3) {
+ aLayers.AppendElement(std::move(layer));
+ }
+ }
+
+ if (back) {
+ BuildDrawOrder(back, aLayers);
+ }
+}
+
+template <typename T>
+void BSPTree<T>::BuildTree(BSPTreeNode<T>* aRoot, PolygonList<T>& aLayers) {
+ MOZ_ASSERT(!aLayers.empty());
+
+ aRoot->layers.push_back(std::move(aLayers.front()));
+ aLayers.pop_front();
+
+ if (aLayers.empty()) {
+ return;
+ }
+
+ const gfx::Polygon& plane = aRoot->First();
+ MOZ_ASSERT(!plane.IsEmpty());
+
+ const gfx::Point4D& planeNormal = plane.GetNormal();
+ const gfx::Point4D& planePoint = plane.GetPoints()[0];
+
+ PolygonList<T> backLayers, frontLayers;
+ for (BSPPolygon<T>& layerPolygon : aLayers) {
+ const nsTArray<gfx::Point4D>& geometry = layerPolygon.geometry->GetPoints();
+
+ // Calculate the plane-point distances for the polygon classification.
+ size_t pos = 0, neg = 0;
+ nsTArray<float> distances = CalculatePointPlaneDistances(
+ geometry, planeNormal, planePoint, pos, neg);
+
+ // Back polygon
+ if (pos == 0 && neg > 0) {
+ backLayers.push_back(std::move(layerPolygon));
+ }
+ // Front polygon
+ else if (pos > 0 && neg == 0) {
+ frontLayers.push_back(std::move(layerPolygon));
+ }
+ // Coplanar polygon
+ else if (pos == 0 && neg == 0) {
+ aRoot->layers.push_back(std::move(layerPolygon));
+ }
+ // Polygon intersects with the splitting plane.
+ else if (pos > 0 && neg > 0) {
+ nsTArray<gfx::Point4D> backPoints, frontPoints;
+ // Clip the polygon against the plane. We reuse the previously calculated
+ // distances to find the plane-edge intersections.
+ ClipPointsWithPlane(geometry, planeNormal, distances, backPoints,
+ frontPoints);
+
+ const gfx::Point4D& normal = layerPolygon.geometry->GetNormal();
+ T* data = layerPolygon.data;
+
+ if (backPoints.Length() >= 3) {
+ backLayers.emplace_back(data, std::move(backPoints), normal);
+ }
+
+ if (frontPoints.Length() >= 3) {
+ frontLayers.emplace_back(data, std::move(frontPoints), normal);
+ }
+ }
+ }
+
+ if (!backLayers.empty()) {
+ aRoot->back = new (mPool) BSPTreeNode(mListPointers);
+ BuildTree(aRoot->back, backLayers);
+ }
+
+ if (!frontLayers.empty()) {
+ aRoot->front = new (mPool) BSPTreeNode(mListPointers);
+ BuildTree(aRoot->front, frontLayers);
+ }
+}
+
+template void BSPTree<BSPTestData>::BuildTree(
+ BSPTreeNode<BSPTestData>* aRoot, PolygonList<BSPTestData>& aLayers);
+template void BSPTree<BSPTestData>::BuildDrawOrder(
+ BSPTreeNode<BSPTestData>* aNode,
+ nsTArray<BSPPolygon<BSPTestData>>& aLayers) const;
+
+template void BSPTree<nsDisplayTransform>::BuildTree(
+ BSPTreeNode<nsDisplayTransform>* aRoot,
+ PolygonList<nsDisplayTransform>& aLayers);
+template void BSPTree<nsDisplayTransform>::BuildDrawOrder(
+ BSPTreeNode<nsDisplayTransform>* aNode,
+ nsTArray<BSPPolygon<nsDisplayTransform>>& aLayers) const;
+
+} // namespace layers
+} // namespace mozilla