DrawPolygon class with Unit Tests

cc/quads/draw_polygon_unittest.cc

Index: cc/quads/draw_polygon_unittest.cc
diff --git a/cc/quads/draw_polygon_unittest.cc b/cc/quads/draw_polygon_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3ee001ad558991f6f7c29cae0f394426021af3a3
--- /dev/null
+++ b/cc/quads/draw_polygon_unittest.cc
@@ -0,0 +1,198 @@
+// 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_compare_result.h"
+#include "cc/quads/draw_polygon.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/transform.h"
+
+namespace cc {
+namespace {
+
+#define CREATE_NEW_DRAW_POLYGON(name, vertex_array, num_vertices, polygon_id) \
+  DrawPolygon name(NULL, vertex_array, num_vertices, polygon_id)
+
+// Two quads are definitely not touching and so no split should occur.
+TEST(DrawPolygonSplitTest, NotTouchingNoSplit) {
+  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(5.0f, 10.0f, 5.0f);
+  vertices_b[1] = gfx::Point3F(5.0f, 0.0f, 15.0f);
+  vertices_b[2] = gfx::Point3F(5.0f, 0.0f, 15.0f);
+  vertices_b[3] = gfx::Point3F(5.0f, 10.0f, 5.0f);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+  CREATE_NEW_DRAW_POLYGON(polygon_b, vertices_b, 4, 1);
+
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                polygon_b, polygon_a, DrawPolygon::compare_threshold),
+            BSP_FRONT);
+}
+
+// One quad is resting against another, but doesn't cross its plane so no split
+// should occur.
+TEST(DrawPolygonSplitTest, BarelyTouchingNoSplit) {
+  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(5.0f, 10.0f, 0.0f);
+  vertices_b[1] = gfx::Point3F(5.0f, 0.0f, -10.0f);
+  vertices_b[2] = gfx::Point3F(5.0f, 0.0f, -10.0f);
+  vertices_b[3] = gfx::Point3F(5.0f, 10.0f, 0.0f);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+  CREATE_NEW_DRAW_POLYGON(polygon_b, vertices_b, 4, 1);
+
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                polygon_b, polygon_a, DrawPolygon::compare_threshold),
+            BSP_BACK);
+}
+
+// One quad intersects another and becomes two pieces.
+TEST(DrawPolygonSplitTest, BasicSplit) {
+  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(5.0f, 10.0f, -5.0f);
+  vertices_b[1] = gfx::Point3F(5.0f, 0.0f, -5.0f);
+  vertices_b[2] = gfx::Point3F(5.0f, 0.0f, 5.0f);
+  vertices_b[3] = gfx::Point3F(5.0f, 10.0f, 5.0f);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+  CREATE_NEW_DRAW_POLYGON(polygon_b, vertices_b, 4, 1);
+
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                polygon_b, polygon_a, DrawPolygon::compare_threshold),
+            BSP_SPLIT);
+
+  scoped_ptr<DrawPolygon> front_polygon;
+  scoped_ptr<DrawPolygon> back_polygon;
+  polygon_b.Split(
+      polygon_a, DrawPolygon::split_threshold, &front_polygon, &back_polygon);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *front_polygon, polygon_a, DrawPolygon::compare_threshold),
+            BSP_FRONT);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *back_polygon, polygon_a, DrawPolygon::compare_threshold),
+            BSP_BACK);
+}
+
+// A "wave" shape of points that do not make up those of a convex polygon
+// crossing the boundaries of another polygon. This should not cause a problem
+// and should still result in two different pieces of geometry on either side.
+TEST(DrawPolygonSplitTest, NonConvexSplit) {
+  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(5.0f, 10.0f, -10.0f);
+  vertices_b[1] = gfx::Point3F(5.0f, 7.5f, -5.0f);
+  vertices_b[2] = gfx::Point3F(5.0f, 5.0f, 0.0f);
+  vertices_b[3] = gfx::Point3F(5.0f, 7.5f, 5.0f);
+  vertices_b[4] = gfx::Point3F(5.0f, 10.0f, 10.0f);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+  CREATE_NEW_DRAW_POLYGON(polygon_b, vertices_b, 5, 1);
+
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                polygon_b, polygon_a, DrawPolygon::compare_threshold),
+            BSP_SPLIT);
+
+  scoped_ptr<DrawPolygon> front_polygon;
+  scoped_ptr<DrawPolygon> back_polygon;
+  polygon_b.Split(
+      polygon_a, DrawPolygon::split_threshold, &front_polygon, &back_polygon);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *front_polygon, polygon_a, DrawPolygon::compare_threshold),
+            BSP_FRONT);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *back_polygon, polygon_a, DrawPolygon::compare_threshold),
+            BSP_BACK);
+}
+
+// In this test we cut the corner of a quad so that it creates a triangle and
+// a pentagon as a result.
+TEST(DrawPolygonSplitTest, AngledSplit) {
+  gfx::Point3F vertices_a[4];
+  vertices_a[0] = gfx::Point3F(0.0f, 0.0f, 0.0f);
+  vertices_a[1] = gfx::Point3F(0.0f, 0.0f, 10.0f);
+  vertices_a[2] = gfx::Point3F(10.0f, 0.0f, 10.0f);
+  vertices_a[3] = gfx::Point3F(10.0f, 0.0f, 0.0f);
+  gfx::Point3F vertices_b[4];
+  vertices_b[0] = gfx::Point3F(2.0f, 5.0f, 1.0f);
+  vertices_b[1] = gfx::Point3F(2.0f, -5.0f, 1.0f);
+  vertices_b[2] = gfx::Point3F(-1.0f, -5.0f, -2.0f);
+  vertices_b[3] = gfx::Point3F(-1.0f, 5.0f, -2.0f);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+  CREATE_NEW_DRAW_POLYGON(polygon_b, vertices_b, 4, 1);
+
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                polygon_a, polygon_b, DrawPolygon::compare_threshold),
+            BSP_SPLIT);
+
+  scoped_ptr<DrawPolygon> front_polygon;
+  scoped_ptr<DrawPolygon> back_polygon;
+  polygon_a.Split(
+      polygon_b, DrawPolygon::split_threshold, &front_polygon, &back_polygon);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *front_polygon, polygon_b, DrawPolygon::compare_threshold),
+            BSP_FRONT);
+  EXPECT_EQ(DrawPolygon::SideCompare(
+                *back_polygon, polygon_b, DrawPolygon::compare_threshold),
+            BSP_BACK);
+
+  EXPECT_EQ(front_polygon->points.size(), static_cast<unsigned int>(3));
+  EXPECT_EQ(back_polygon->points.size(), static_cast<unsigned int>(5));
+}
+
+// Testing the area calculation on a basic flat 10x10 quad.
+TEST(DrawPolygonAreaTest, Basic) {
+  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);
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+
+  EXPECT_EQ(polygon_a.area, 100.0f);
+}
+
+// Same quad as before, but with transformations applied to it. This shows that
+// the area calculation works on arbitrarily transformed geometry.
+TEST(DrawPolygonAreaTest, TransformedPolygon) {
+  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::Transform transform;
+  transform.RotateAboutXAxis(30.0);
+  transform.RotateAboutYAxis(40.0);
+  transform.RotateAboutZAxis(50.0);
+  for (int i = 0; i < 4; i++) {
+    transform.TransformPoint(&vertices_a[i]);
+  }
+
+  CREATE_NEW_DRAW_POLYGON(polygon_a, vertices_a, 4, 0);
+
+  EXPECT_EQ(polygon_a.area, 100.0f);
+}
+
+}  // namespace
+}  // namespace cc