WIP BSP Tree for 3D Layer Sorting

cc/output/bsp_tree_unittest.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "cc/base/scoped_ptr_vector.h"
+#include "cc/output/bsp_controller.h"
+#include "cc/output/bsp_tree.h"
+#include "cc/output/bsp_walk_action.h"
+#include "cc/quads/draw_polygon.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+namespace {
+
+class TestBspController : public BspController {
+ public:
+  TestBspController() : BspController() {}
+  // Since the weights of polygons affect what order they're placed in the tree,
+  // it's important that we don't break unit tests if the heuristic is ever
+  // changed. By simply forcing all the weights to be 0, the polygons will all
+  // be put into the tree in the same order as they're given, and the unit tests
+  // won't be affected by changing heuristics.
+  virtual float SplitWeight(const DrawPolygon& poly) OVERRIDE { return 0.0f; }
+};
+
+#define EXPECT_SORTED_LISTS_EQ(polygon_list, compare_list)      \
+  do {                                                          \
+    EXPECT_EQ(polygon_list.size(), compare_list.size());        \
+    for (unsigned int i = 0; i < polygon_list.size(); i++) {    \
+      EXPECT_EQ(polygon_list[i]->order_index, compare_list[i]); \
+    }                                                           \
+  } while (false);
+
+#define INT_VECTOR_FROM_ARRAY(array) \
+  std::vector<int>(array, array + arraysize(array))
+
+class BspTreeTest {
+ public:
+  static void RunTest(ScopedPtrVector<DrawPolygon>* test_polygons,
+                      const std::vector<int>& compare_list) {
+    TestBspController bsp_controller;
+    BspTree bsp_tree(&bsp_controller, test_polygons);
+
+    std::vector<DrawPolygon*> sorted_list;
+    BspWalkActionToVector action_handler(&sorted_list);
+    bsp_tree.TraverseWithActionHandler(&action_handler);
+
+    EXPECT_SORTED_LISTS_EQ(sorted_list, compare_list);
+    EXPECT_TRUE(VerifySidedness(bsp_tree.root()));
+  }
+
+  static bool VerifySidedness(const scoped_ptr<BspNode>& node) {
+    // We check if both the front and back child nodes have geometry that is
+    // completely on the expected side of the current node.
+    bool front_ok = true;
+    bool back_ok = true;
+    if (node->back_child) {
+      // Make sure the back child lies entirely behind this node.
+      if (!GeometrySide(node, node->back_child->node_data.get(), BSP_BACK)) {
+        return false;
+      }
+      back_ok = VerifySidedness(node->back_child);
+    }
+    // Make sure the front child lies entirely in front of this node.
+    if (node->front_child) {
+      if (!GeometrySide(node, node->front_child->node_data.get(), BSP_FRONT)) {
+        return false;
+      }
+      front_ok = VerifySidedness(node->front_child);
+    }
+    if (!back_ok || !front_ok) {
+      return false;
+    }
+
+    // Now we need to make sure our coplanar geometry is all actually coplanar.
+    for (unsigned int i = 0; i < node->coplanars_front.size(); i++) {
+      if (!GeometrySide(node, node->coplanars_front[i], BSP_COPLANAR)) {
+        return false;
+      }
+    }
+    for (unsigned int i = 0; i < node->coplanars_back.size(); i++) {
+      if (!GeometrySide(node, node->coplanars_back[i], BSP_COPLANAR)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  static bool GeometrySide(const scoped_ptr<BspNode>& parent,
+                           DrawPolygon* child_data,
+                           BspCompareResult side) {
+    for (unsigned int i = 0; i < child_data->points.size(); i++) {
+      float p_distance =
+          parent->node_data->SignedPointDistance(child_data->points[i]);
+      switch (side) {
+        case BSP_BACK:
+          if (p_distance > BspController::compare_threshold) {
+            return false;
+          }
+          break;
+        case BSP_FRONT:
+          if (p_distance < -BspController::compare_threshold) {
+            return false;
+          }
+          break;
+        case BSP_COPLANAR:
+          if (std::abs(p_distance) > BspController::compare_threshold) {
+            return false;
+          }
+          break;
+        default:
+          NOTREACHED();
+          break;
+      }
+    }
+    return true;
+  }
+};
+
+// Simple standing quads all parallel with each other, causing no splits.
+TEST(BspTreeTest, NoSplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(0.0f, 10.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(0.0f, 0.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(10.0f, 0.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(10.0f, 10.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(0.0f, 10.0f, -5.0f);
+  vertices_b[1] = gfx::Point3F(0.0f, 0.0f, -5.0f);
+  vertices_b[2] = gfx::Point3F(10.0f, 0.0f, -5.0f);
+  vertices_b[3] = gfx::Point3F(10.0f, 10.0f, -5.0f);
+  gfx::Point3F vertices_c[4];
+  vertices_c[0] = gfx::Point3F(0.0f, 10.0f, 5.0f);
+  vertices_c[1] = gfx::Point3F(0.0f, 0.0f, 5.0f);
+  vertices_c[2] = gfx::Point3F(10.0f, 0.0f, 5.0f);
+  vertices_c[3] = gfx::Point3F(10.0f, 10.0f, 5.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  scoped_ptr<DrawPolygon> polygon_c(
+      new DrawPolygon(NULL, vertices_c, 4, 2, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+  polygon_list.push_back(polygon_c.Pass());
+
+  int compare_ids[] = {1, 0, 2};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// Basic two polygon split, can be viewed as a + from above.
+TEST(BspTreeTest, BasicSplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(0.0f, 5.0f, -5.0f);
+  vertices_b[1] = gfx::Point3F(0.0f, -5.0f, -5.0f);
+  vertices_b[2] = gfx::Point3F(0.0f, -5.0f, 5.0f);
+  vertices_b[3] = gfx::Point3F(0.0f, 5.0f, 5.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+
+  int compare_ids[] = {1, 0, 1};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// Same as above with the second quad offset so it doesn't intersect. One quad
+// should be very clearly on one side of the other, and no splitting should
+// occur.
+TEST(BspTreeTest, QuadOffset) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(0.0f, 5.0f, -15.0f);
+  vertices_b[1] = gfx::Point3F(0.0f, -5.0f, -15.0f);
+  vertices_b[2] = gfx::Point3F(0.0f, -5.0f, -10.0f);
+  vertices_b[3] = gfx::Point3F(0.0f, 5.0f, -10.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+
+  int compare_ids[] = {1, 0};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// Same as above, but this time we change the order in which the quads are
+// inserted into the tree, causing one to actually cross the plane of the other
+// and cause a split.
+TEST(BspTreeTest, QuadOffsetSplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(0.0f, 5.0f, -15.0f);
+  vertices_b[1] = gfx::Point3F(0.0f, -5.0f, -15.0f);
+  vertices_b[2] = gfx::Point3F(0.0f, -5.0f, -10.0f);
+  vertices_b[3] = gfx::Point3F(0.0f, 5.0f, -10.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_b.Pass());
+  polygon_list.push_back(polygon_a.Pass());
+
+  int compare_ids[] = {0, 1, 0};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// In addition to what can be viewed as a + from above, another piece of
+// geometry is inserted to cut these pieces right in the middle, viewed as
+// a quad from overhead.
+TEST(BspTreeTest, ThreeWaySplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(0.0f, 5.0f, -5.0f);
+  vertices_b[1] = gfx::Point3F(0.0f, -5.0f, -5.0f);
+  vertices_b[2] = gfx::Point3F(0.0f, -5.0f, 5.0f);
+  vertices_b[3] = gfx::Point3F(0.0f, 5.0f, 5.0f);
+  gfx::Point3F vertices_c[4];
+  vertices_c[0] = gfx::Point3F(-5.0f, 0.0f, 5.0f);
+  vertices_c[1] = gfx::Point3F(-5.0f, 0.0f, -5.0f);
+  vertices_c[2] = gfx::Point3F(5.0f, 0.0f, -5.0f);
+  vertices_c[3] = gfx::Point3F(5.0f, 0.0f, 5.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  scoped_ptr<DrawPolygon> polygon_c(
+      new DrawPolygon(NULL, vertices_c, 4, 2, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+  polygon_list.push_back(polygon_c.Pass());
+
+  int compare_ids[] = {2, 1, 2, 0, 2, 1, 2};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// This test checks whether coplanar geometry, when inserted into the tree in
+// order, comes back in the same order as it should.
+TEST(BspTreeTest, Coplanar) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(-4.0f, 4.0f, 0.0f);
+  vertices_b[1] = gfx::Point3F(-4.0f, -4.0f, 0.0f);
+  vertices_b[2] = gfx::Point3F(4.0f, -4.0f, 0.0f);
+  vertices_b[3] = gfx::Point3F(4.0f, 4.0f, 0.0f);
+  gfx::Point3F vertices_c[4];
+  vertices_c[0] = gfx::Point3F(-3.0f, 3.0f, 0.0f);
+  vertices_c[1] = gfx::Point3F(-3.0f, -3.0f, 0.0f);
+  vertices_c[2] = gfx::Point3F(3.0f, -3.0f, 0.0f);
+  vertices_c[3] = gfx::Point3F(3.0f, 3.0f, 0.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  scoped_ptr<DrawPolygon> polygon_c(
+      new DrawPolygon(NULL, vertices_c, 4, 2, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+  polygon_list.push_back(polygon_c.Pass());
+
+  int compare_ids[] = {0, 1, 2};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+// A bunch of coplanar geometry should end up sharing a single node, and
+// result in the final piece of geometry splitting into just two pieces on
+// either side of the shared plane.
+TEST(BspTreeTest, CoplanarSplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(-5.0f, 5.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(-5.0f, -5.0f, 0.0f);
+  vertices_a[2] = gfx::Point3F(5.0f, -5.0f, 0.0f);
+  vertices_a[3] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(-4.0f, 4.0f, 0.0f);
+  vertices_b[1] = gfx::Point3F(-4.0f, -4.0f, 0.0f);
+  vertices_b[2] = gfx::Point3F(4.0f, -4.0f, 0.0f);
+  vertices_b[3] = gfx::Point3F(4.0f, 4.0f, 0.0f);
+  gfx::Point3F vertices_c[4];
+  vertices_c[0] = gfx::Point3F(-3.0f, 3.0f, 0.0f);
+  vertices_c[1] = gfx::Point3F(-3.0f, -3.0f, 0.0f);
+  vertices_c[2] = gfx::Point3F(3.0f, -3.0f, 0.0f);
+  vertices_c[3] = gfx::Point3F(3.0f, 3.0f, 0.0f);
+  gfx::Point3F vertices_d[4];
+  vertices_d[0] = gfx::Point3F(0.0f, 15.0f, -15.0f);
+  vertices_d[1] = gfx::Point3F(0.0f, -15.0f, -15.0f);
+  vertices_d[2] = gfx::Point3F(0.0f, -15.0f, 15.0f);
+  vertices_d[3] = gfx::Point3F(0.0f, 15.0f, 15.0f);
+
+  scoped_ptr<DrawPolygon> polygon_a(
+      new DrawPolygon(NULL, vertices_a, 4, 0, true));
+  scoped_ptr<DrawPolygon> polygon_b(
+      new DrawPolygon(NULL, vertices_b, 4, 1, true));
+  scoped_ptr<DrawPolygon> polygon_c(
+      new DrawPolygon(NULL, vertices_c, 4, 2, true));
+  scoped_ptr<DrawPolygon> polygon_d(
+      new DrawPolygon(NULL, vertices_d, 4, 3, true));
+  ScopedPtrVector<DrawPolygon> polygon_list;
+  polygon_list.push_back(polygon_a.Pass());
+  polygon_list.push_back(polygon_b.Pass());
+  polygon_list.push_back(polygon_c.Pass());
+  polygon_list.push_back(polygon_d.Pass());
+
+  int compare_ids[] = {3, 0, 1, 2, 3};
+  std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
+  BspTreeTest::RunTest(&polygon_list, compare_list);
+}
+
+}  // namespace
+}  // namespace cc