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 "cc/output/bsp_tree.h"

#include <stddef.h>

#include <deque>
#include <memory>

#include "base/macros.h"
#include "cc/output/bsp_walk_action.h"
#include "cc/quads/draw_polygon.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace cc {
namespace {

#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))

#define CREATE_DRAW_POLYGON(vertex_vector, normal, polygon_id) \
  new DrawPolygon(NULL, vertex_vector, normal, polygon_id)

class BspTreeTest {
 public:
  static void RunTest(std::deque<std::unique_ptr<DrawPolygon>>* test_polygons,
                      const std::vector<int>& compare_list) {
    BspTree bsp_tree(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 BspCompareResult SideCompare(const DrawPolygon& a,
                                      const DrawPolygon& b) {
    const float split_threshold = 0.05f;
    bool pos = false;
    bool neg = false;
    for (const auto& pt : a.points()) {
      float dist = b.SignedPointDistance(pt);
      neg |= dist < -split_threshold;
      pos |= dist > split_threshold;
    }
    if (pos && neg)
      return BSP_SPLIT;
    if (neg)
      return BSP_BACK;
    if (pos)
      return BSP_FRONT;
    double dot = gfx::DotProduct(a.normal(), b.normal());
    if ((dot >= 0.0f && a.order_index() >= b.order_index()) ||
        (dot <= 0.0f && a.order_index() <= b.order_index())) {
      // The sign of the dot product of the normals along with document order
      // determine which side it goes on, the vertices are ambiguous.
      return BSP_COPLANAR_BACK;
    }
    return BSP_COPLANAR_FRONT;
  }

  static bool VerifySidedness(const std::unique_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.
      BspCompareResult result =
          SideCompare(*(node->back_child->node_data), *(node->node_data));
      if (result != 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) {
      BspCompareResult result =
          SideCompare(*(node->front_child->node_data), *(node->node_data));
      if (result != 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 (size_t i = 0; i < node->coplanars_front.size(); i++) {
      BspCompareResult result =
          SideCompare(*(node->coplanars_front[i]), *(node->node_data));
      if (result != BSP_COPLANAR_FRONT) {
        return false;
      }
    }
    for (size_t i = 0; i < node->coplanars_back.size(); i++) {
      BspCompareResult result =
          SideCompare(*(node->coplanars_back[i]), *(node->node_data));
      if (result != BSP_COPLANAR_BACK) {
        return false;
      }
    }
    return true;
  }
};

// Simple standing quads all parallel with each other, causing no splits.
TEST(BspTreeTest, NoSplit) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(0.0f, 10.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(0.0f, 0.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(10.0f, 0.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(10.0f, 10.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(0.0f, 10.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 0.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(10.0f, 0.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(10.0f, 10.0f, -5.0f));
  std::vector<gfx::Point3F> vertices_c;
  vertices_c.push_back(gfx::Point3F(0.0f, 10.0f, 5.0f));
  vertices_c.push_back(gfx::Point3F(0.0f, 0.0f, 5.0f));
  vertices_c.push_back(gfx::Point3F(10.0f, 0.0f, 5.0f));
  vertices_c.push_back(gfx::Point3F(10.0f, 10.0f, 5.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 1));
  std::unique_ptr<DrawPolygon> polygon_c(
      CREATE_DRAW_POLYGON(vertices_c, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 2));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_a));
  polygon_list.push_back(std::move(polygon_b));
  polygon_list.push_back(std::move(polygon_c));

  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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, 5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, 5.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(-1.0f, 0.0f, 0.0f), 1));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_a));
  polygon_list.push_back(std::move(polygon_b));

  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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -15.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -15.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -10.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -10.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(-1.0f, 0.0f, 0.0f), 1));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_a));
  polygon_list.push_back(std::move(polygon_b));

  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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -15.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -15.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -10.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -10.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(-1.0f, 0.0f, 0.0f), 1));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_b));
  polygon_list.push_back(std::move(polygon_a));

  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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, -5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, 5.0f, 5.0f));
  vertices_b.push_back(gfx::Point3F(0.0f, -5.0f, 5.0f));
  std::vector<gfx::Point3F> vertices_c;
  vertices_c.push_back(gfx::Point3F(-5.0f, 0.0f, -5.0f));
  vertices_c.push_back(gfx::Point3F(-5.0f, 0.0f, 5.0f));
  vertices_c.push_back(gfx::Point3F(5.0f, 0.0f, 5.0f));
  vertices_c.push_back(gfx::Point3F(5.0f, 0.0f, -5.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(-1.0f, 0.0f, 0.0f), 1));
  std::unique_ptr<DrawPolygon> polygon_c(
      CREATE_DRAW_POLYGON(vertices_c, gfx::Vector3dF(0.0f, 1.0f, 0.0f), 2));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_a));
  polygon_list.push_back(std::move(polygon_b));
  polygon_list.push_back(std::move(polygon_c));

  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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(-4.0f, -4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(-4.0f, 4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(4.0f, 4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(4.0f, -4.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_c;
  vertices_c.push_back(gfx::Point3F(-3.0f, -3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(-3.0f, 3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(3.0f, 3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(3.0f, -3.0f, 0.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 1));
  std::unique_ptr<DrawPolygon> polygon_c(
      CREATE_DRAW_POLYGON(vertices_c, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 2));

  std::unique_ptr<DrawPolygon> polygon_d = polygon_a->CreateCopy();
  std::unique_ptr<DrawPolygon> polygon_e = polygon_b->CreateCopy();
  std::unique_ptr<DrawPolygon> polygon_f = polygon_c->CreateCopy();

  {
    std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
    polygon_list.push_back(std::move(polygon_a));
    polygon_list.push_back(std::move(polygon_b));
    polygon_list.push_back(std::move(polygon_c));

    int compare_ids[] = {0, 1, 2};
    std::vector<int> compare_list = INT_VECTOR_FROM_ARRAY(compare_ids);
    BspTreeTest::RunTest(&polygon_list, compare_list);
  }

  // Now check a different order and ensure we get that back as well
  {
    std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
    polygon_list.push_back(std::move(polygon_f));
    polygon_list.push_back(std::move(polygon_d));
    polygon_list.push_back(std::move(polygon_e));

    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) {
  std::vector<gfx::Point3F> vertices_a;
  vertices_a.push_back(gfx::Point3F(-5.0f, -5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(-5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, 5.0f, 0.0f));
  vertices_a.push_back(gfx::Point3F(5.0f, -5.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_b;
  vertices_b.push_back(gfx::Point3F(-4.0f, -4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(-4.0f, 4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(4.0f, 4.0f, 0.0f));
  vertices_b.push_back(gfx::Point3F(4.0f, -4.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_c;
  vertices_c.push_back(gfx::Point3F(-3.0f, -3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(-3.0f, 3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(3.0f, 3.0f, 0.0f));
  vertices_c.push_back(gfx::Point3F(3.0f, -3.0f, 0.0f));
  std::vector<gfx::Point3F> vertices_d;
  vertices_d.push_back(gfx::Point3F(0.0f, -15.0f, -15.0f));
  vertices_d.push_back(gfx::Point3F(0.0f, 15.0f, -15.0f));
  vertices_d.push_back(gfx::Point3F(0.0f, 15.0f, 15.0f));
  vertices_d.push_back(gfx::Point3F(0.0f, -15.0f, 15.0f));

  std::unique_ptr<DrawPolygon> polygon_a(
      CREATE_DRAW_POLYGON(vertices_a, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 0));
  std::unique_ptr<DrawPolygon> polygon_b(
      CREATE_DRAW_POLYGON(vertices_b, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 1));
  std::unique_ptr<DrawPolygon> polygon_c(
      CREATE_DRAW_POLYGON(vertices_c, gfx::Vector3dF(0.0f, 0.0f, 1.0f), 2));
  std::unique_ptr<DrawPolygon> polygon_d(
      CREATE_DRAW_POLYGON(vertices_d, gfx::Vector3dF(-1.0f, 0.0f, 0.0f), 3));

  std::deque<std::unique_ptr<DrawPolygon>> polygon_list;
  polygon_list.push_back(std::move(polygon_a));
  polygon_list.push_back(std::move(polygon_b));
  polygon_list.push_back(std::move(polygon_c));
  polygon_list.push_back(std::move(polygon_d));

  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