cc/base/math_util_unittest.cc

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/base/math_util.h"
   6
   7 #include <cmath>
   8
   9 #include "cc/test/geometry_test_utils.h"
  10 #include "testing/gmock/include/gmock/gmock.h"
  11 #include "testing/gtest/include/gtest/gtest.h"
  12 #include "ui/gfx/rect.h"
  13 #include "ui/gfx/rect_f.h"
  14 #include "ui/gfx/transform.h"
  15
  16 namespace cc {
  17 namespace {
  18
  19 TEST(MathUtilTest, ProjectionOfPerpendicularPlane) {
  20   // In this case, the m33() element of the transform becomes zero, which could
  21   // cause a divide-by-zero when projecting points/quads.
  22
  23   gfx::Transform transform;
  24   transform.MakeIdentity();
  25   transform.matrix().set(2, 2, 0);
  26
  27   gfx::RectF rect = gfx::RectF(0, 0, 1, 1);
  28   gfx::RectF projected_rect = MathUtil::ProjectClippedRect(transform, rect);
  29
  30   EXPECT_EQ(0, projected_rect.x());
  31   EXPECT_EQ(0, projected_rect.y());
  32   EXPECT_TRUE(projected_rect.IsEmpty());
  33 }
  34
  35 TEST(MathUtilTest, EnclosingClippedRectUsesCorrectInitialBounds) {
  36   HomogeneousCoordinate h1(-100, -100, 0, 1);
  37   HomogeneousCoordinate h2(-10, -10, 0, 1);
  38   HomogeneousCoordinate h3(10, 10, 0, -1);
  39   HomogeneousCoordinate h4(100, 100, 0, -1);
  40
  41   // The bounds of the enclosing clipped rect should be -100 to -10 for both x
  42   // and y. However, if there is a bug where the initial xmin/xmax/ymin/ymax are
  43   // initialized to numeric_limits<float>::min() (which is zero, not -flt_max)
  44   // then the enclosing clipped rect will be computed incorrectly.
  45   gfx::RectF result = MathUtil::ComputeEnclosingClippedRect(h1, h2, h3, h4);
  46
  47   // Due to floating point math in ComputeClippedPointForEdge this result
  48   // is fairly imprecise.  0.15f was empirically determined.
  49   EXPECT_RECT_NEAR(
  50       gfx::RectF(gfx::PointF(-100, -100), gfx::SizeF(90, 90)), result, 0.15f);
  51 }
  52
  53 TEST(MathUtilTest, EnclosingRectOfVerticesUsesCorrectInitialBounds) {
  54   gfx::PointF vertices[3];
  55   int num_vertices = 3;
  56
  57   vertices[0] = gfx::PointF(-10, -100);
  58   vertices[1] = gfx::PointF(-100, -10);
  59   vertices[2] = gfx::PointF(-30, -30);
  60
  61   // The bounds of the enclosing rect should be -100 to -10 for both x and y.
  62   // However, if there is a bug where the initial xmin/xmax/ymin/ymax are
  63   // initialized to numeric_limits<float>::min() (which is zero, not -flt_max)
  64   // then the enclosing clipped rect will be computed incorrectly.
  65   gfx::RectF result =
  66       MathUtil::ComputeEnclosingRectOfVertices(vertices, num_vertices);
  67
  68   EXPECT_FLOAT_RECT_EQ(gfx::RectF(gfx::PointF(-100, -100), gfx::SizeF(90, 90)),
  69                        result);
  70 }
  71
  72 TEST(MathUtilTest, SmallestAngleBetweenVectors) {
  73   gfx::Vector2dF x(1, 0);
  74   gfx::Vector2dF y(0, 1);
  75   gfx::Vector2dF test_vector(0.5, 0.5);
  76
  77   // Orthogonal vectors are at an angle of 90 degress.
  78   EXPECT_EQ(90, MathUtil::SmallestAngleBetweenVectors(x, y));
  79
  80   // A vector makes a zero angle with itself.
  81   EXPECT_EQ(0, MathUtil::SmallestAngleBetweenVectors(x, x));
  82   EXPECT_EQ(0, MathUtil::SmallestAngleBetweenVectors(y, y));
  83   EXPECT_EQ(0, MathUtil::SmallestAngleBetweenVectors(test_vector, test_vector));
  84
  85   // Parallel but reversed vectors are at 180 degrees.
  86   EXPECT_FLOAT_EQ(180, MathUtil::SmallestAngleBetweenVectors(x, -x));
  87   EXPECT_FLOAT_EQ(180, MathUtil::SmallestAngleBetweenVectors(y, -y));
  88   EXPECT_FLOAT_EQ(
  89       180, MathUtil::SmallestAngleBetweenVectors(test_vector, -test_vector));
  90
  91   // The test vector is at a known angle.
  92   EXPECT_FLOAT_EQ(
  93       45, std::floor(MathUtil::SmallestAngleBetweenVectors(test_vector, x)));
  94   EXPECT_FLOAT_EQ(
  95       45, std::floor(MathUtil::SmallestAngleBetweenVectors(test_vector, y)));
  96 }
  97
  98 TEST(MathUtilTest, VectorProjection) {
  99   gfx::Vector2dF x(1, 0);
 100   gfx::Vector2dF y(0, 1);
 101   gfx::Vector2dF test_vector(0.3f, 0.7f);
 102
 103   // Orthogonal vectors project to a zero vector.
 104   EXPECT_VECTOR_EQ(gfx::Vector2dF(0, 0), MathUtil::ProjectVector(x, y));
 105   EXPECT_VECTOR_EQ(gfx::Vector2dF(0, 0), MathUtil::ProjectVector(y, x));
 106
 107   // Projecting a vector onto the orthonormal basis gives the corresponding
 108   // component of the vector.
 109   EXPECT_VECTOR_EQ(gfx::Vector2dF(test_vector.x(), 0),
 110                    MathUtil::ProjectVector(test_vector, x));
 111   EXPECT_VECTOR_EQ(gfx::Vector2dF(0, test_vector.y()),
 112                    MathUtil::ProjectVector(test_vector, y));
 113
 114   // Finally check than an arbitrary vector projected to another one gives a
 115   // vector parallel to the second vector.
 116   gfx::Vector2dF target_vector(0.5, 0.2f);
 117   gfx::Vector2dF projected_vector =
 118       MathUtil::ProjectVector(test_vector, target_vector);
 119   EXPECT_EQ(projected_vector.x() / target_vector.x(),
 120             projected_vector.y() / target_vector.y());
 121 }
 122
 123 }  // namespace
 124 }  // namespace cc