Flutter Impeller
gaussian_blur_filter_contents_unittests.cc
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1 // Copyright 2013 The Flutter 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 "flutter/testing/testing.h"
6 #include "fml/status_or.h"
7 #include "gmock/gmock.h"
12 #include "impeller/renderer/testing/mocks.h"
13 
14 #if FML_OS_MACOSX
15 #define IMPELLER_RAND arc4random
16 #else
17 #define IMPELLER_RAND rand
18 #endif
19 
20 namespace impeller {
21 namespace testing {
22 
23 namespace {
24 
25 // Use newtonian method to give the closest answer to target where
26 // f(x) is less than the target. We do this because the value is `ceil`'d to
27 // grab fractional pixels.
28 fml::StatusOr<float> LowerBoundNewtonianMethod(
29  const std::function<float(float)>& func,
30  float target,
31  float guess,
32  float tolerance) {
33  const double delta = 1e-6;
34  double x = guess;
35  double fx;
36  static const int kMaxIterations = 1000;
37  int count = 0;
38 
39  do {
40  fx = func(x) - target;
41  double derivative = (func(x + delta) - func(x)) / delta;
42  x = x - fx / derivative;
43  if (++count > kMaxIterations) {
44  return fml::Status(fml::StatusCode::kDeadlineExceeded,
45  "Did not converge on answer.");
46  }
47  } while (std::abs(fx) > tolerance ||
48  fx < 0.0); // fx < 0.0 makes this lower bound.
49 
50  return x;
51 }
52 
53 fml::StatusOr<Scalar> CalculateSigmaForBlurRadius(
54  Scalar radius,
55  const Matrix& effect_transform) {
56  auto f = [effect_transform](Scalar x) -> Scalar {
57  Vector2 scaled_sigma = (effect_transform.Basis() *
60  .Abs();
61  Vector2 blur_radius = Vector2(
64  return std::max(blur_radius.x, blur_radius.y);
65  };
66  // The newtonian method is used here since inverting the function is
67  // non-trivial because of conditional logic and would be fragile to changes.
68  return LowerBoundNewtonianMethod(f, radius, 2.f, 0.001f);
69 }
70 
71 } // namespace
72 
74  public:
75  /// Create a texture that has been cleared to transparent black.
76  std::shared_ptr<Texture> MakeTexture(ISize size) {
77  auto render_target = GetContentContext()->MakeSubpass(
78  "Clear Subpass", size,
79  [](const ContentContext&, RenderPass&) { return true; });
80  if (render_target.ok()) {
81  return render_target.value().GetRenderTargetTexture();
82  }
83  return nullptr;
84  }
85 };
86 INSTANTIATE_PLAYGROUND_SUITE(GaussianBlurFilterContentsTest);
87 
90  /*sigma_x=*/0.0, /*sigma_y=*/0.0, Entity::TileMode::kDecal,
91  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
92  EXPECT_EQ(contents.GetSigmaX(), 0.0);
93  EXPECT_EQ(contents.GetSigmaY(), 0.0);
94 }
95 
98  /*sigma_x=*/0.0, /*sigma_y=*/0.0, Entity::TileMode::kDecal,
99  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
100  FilterInput::Vector inputs = {};
101  Entity entity;
102  std::optional<Rect> coverage =
103  contents.GetFilterCoverage(inputs, entity, /*effect_transform=*/Matrix());
104  ASSERT_FALSE(coverage.has_value());
105 }
106 
109  /*sigma_x=*/0.0, /*sigma_y=*/0.0, Entity::TileMode::kDecal,
110  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
111  FilterInput::Vector inputs = {
112  FilterInput::Make(Rect::MakeLTRB(10, 10, 110, 110))};
113  Entity entity;
114  std::optional<Rect> coverage =
115  contents.GetFilterCoverage(inputs, entity, /*effect_transform=*/Matrix());
116 
117  ASSERT_EQ(coverage, Rect::MakeLTRB(10, 10, 110, 110));
118 }
119 
121  fml::StatusOr<Scalar> sigma_radius_1 =
122  CalculateSigmaForBlurRadius(1.0, Matrix());
123  ASSERT_TRUE(sigma_radius_1.ok());
125  /*sigma_x=*/sigma_radius_1.value(),
126  /*sigma_y=*/sigma_radius_1.value(), Entity::TileMode::kDecal,
127  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
128  FilterInput::Vector inputs = {
129  FilterInput::Make(Rect::MakeLTRB(100, 100, 200, 200))};
130  Entity entity;
131  std::optional<Rect> coverage =
132  contents.GetFilterCoverage(inputs, entity, /*effect_transform=*/Matrix());
133 
134  EXPECT_TRUE(coverage.has_value());
135  if (coverage.has_value()) {
136  EXPECT_RECT_NEAR(coverage.value(), Rect::MakeLTRB(99, 99, 201, 201));
137  }
138 }
139 
140 TEST_P(GaussianBlurFilterContentsTest, CoverageWithTexture) {
141  fml::StatusOr<Scalar> sigma_radius_1 =
142  CalculateSigmaForBlurRadius(1.0, Matrix());
143  ASSERT_TRUE(sigma_radius_1.ok());
145  /*sigma_X=*/sigma_radius_1.value(),
146  /*sigma_y=*/sigma_radius_1.value(), Entity::TileMode::kDecal,
147  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
148  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
149  FilterInput::Vector inputs = {FilterInput::Make(texture)};
150  Entity entity;
151  entity.SetTransform(Matrix::MakeTranslation({100, 100, 0}));
152  std::optional<Rect> coverage =
153  contents.GetFilterCoverage(inputs, entity, /*effect_transform=*/Matrix());
154 
155  EXPECT_TRUE(coverage.has_value());
156  if (coverage.has_value()) {
157  EXPECT_RECT_NEAR(coverage.value(), Rect::MakeLTRB(99, 99, 201, 201));
158  }
159 }
160 
161 TEST_P(GaussianBlurFilterContentsTest, CoverageWithEffectTransform) {
162  Matrix effect_transform = Matrix::MakeScale({2.0, 2.0, 1.0});
163  fml::StatusOr<Scalar> sigma_radius_1 =
164  CalculateSigmaForBlurRadius(1.0, effect_transform);
165  ASSERT_TRUE(sigma_radius_1.ok());
167  /*sigma_x=*/sigma_radius_1.value(),
168  /*sigma_y=*/sigma_radius_1.value(), Entity::TileMode::kDecal,
169  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
170  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
171  FilterInput::Vector inputs = {FilterInput::Make(texture)};
172  Entity entity;
173  entity.SetTransform(Matrix::MakeTranslation({100, 100, 0}));
174  std::optional<Rect> coverage =
175  contents.GetFilterCoverage(inputs, entity, effect_transform);
176  EXPECT_TRUE(coverage.has_value());
177  if (coverage.has_value()) {
178  EXPECT_RECT_NEAR(coverage.value(),
179  Rect::MakeLTRB(100 - 1, 100 - 1, 200 + 1, 200 + 1));
180  }
181 }
182 
183 TEST(GaussianBlurFilterContentsTest, FilterSourceCoverage) {
184  fml::StatusOr<Scalar> sigma_radius_1 =
185  CalculateSigmaForBlurRadius(1.0, Matrix());
186  ASSERT_TRUE(sigma_radius_1.ok());
187  auto contents = std::make_unique<GaussianBlurFilterContents>(
188  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
189  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
190  std::optional<Rect> coverage = contents->GetFilterSourceCoverage(
191  /*effect_transform=*/Matrix::MakeScale({2.0, 2.0, 1.0}),
192  /*output_limit=*/Rect::MakeLTRB(100, 100, 200, 200));
193  EXPECT_TRUE(coverage.has_value());
194  if (coverage.has_value()) {
195  EXPECT_RECT_NEAR(coverage.value(),
196  Rect::MakeLTRB(100 - 2, 100 - 2, 200 + 2, 200 + 2));
197  }
198 }
199 
200 TEST(GaussianBlurFilterContentsTest, CalculateSigmaValues) {
201  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(1.0f), 1);
202  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(2.0f), 1);
203  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(3.0f), 1);
204  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(4.0f), 1);
205  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(16.0f), 0.25);
206  // Hang on to 1/8 as long as possible.
207  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(95.0f), 0.125);
208  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(96.0f), 0.0625);
209  // Downsample clamped to 1/16th.
210  EXPECT_EQ(GaussianBlurFilterContents::CalculateScale(1024.0f), 0.0625);
211 }
212 
213 TEST_P(GaussianBlurFilterContentsTest, RenderCoverageMatchesGetCoverage) {
214  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
215  fml::StatusOr<Scalar> sigma_radius_1 =
216  CalculateSigmaForBlurRadius(1.0, Matrix());
217  ASSERT_TRUE(sigma_radius_1.ok());
218  auto contents = std::make_unique<GaussianBlurFilterContents>(
219  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
220  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
221  contents->SetInputs({FilterInput::Make(texture)});
222  std::shared_ptr<ContentContext> renderer = GetContentContext();
223 
224  Entity entity;
225  std::optional<Entity> result =
226  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
227  EXPECT_TRUE(result.has_value());
228  if (result.has_value()) {
229  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
230  std::optional<Rect> result_coverage = result.value().GetCoverage();
231  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
232  EXPECT_TRUE(result_coverage.has_value());
233  EXPECT_TRUE(contents_coverage.has_value());
234  if (result_coverage.has_value() && contents_coverage.has_value()) {
235  EXPECT_TRUE(RectNear(contents_coverage.value(),
236  Rect::MakeLTRB(-1, -1, 101, 101)));
237  EXPECT_TRUE(
238  RectNear(result_coverage.value(), Rect::MakeLTRB(-1, -1, 101, 101)));
239  }
240  }
241 }
242 
244  RenderCoverageMatchesGetCoverageTranslate) {
245  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
246  fml::StatusOr<Scalar> sigma_radius_1 =
247  CalculateSigmaForBlurRadius(1.0, Matrix());
248  ASSERT_TRUE(sigma_radius_1.ok());
249  auto contents = std::make_unique<GaussianBlurFilterContents>(
250  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
251  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
252  contents->SetInputs({FilterInput::Make(texture)});
253  std::shared_ptr<ContentContext> renderer = GetContentContext();
254 
255  Entity entity;
256  entity.SetTransform(Matrix::MakeTranslation({100, 200, 0}));
257  std::optional<Entity> result =
258  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
259 
260  EXPECT_TRUE(result.has_value());
261  if (result.has_value()) {
262  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
263  std::optional<Rect> result_coverage = result.value().GetCoverage();
264  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
265  EXPECT_TRUE(result_coverage.has_value());
266  EXPECT_TRUE(contents_coverage.has_value());
267  if (result_coverage.has_value() && contents_coverage.has_value()) {
268  EXPECT_TRUE(RectNear(contents_coverage.value(),
269  Rect::MakeLTRB(99, 199, 201, 301)));
270  EXPECT_TRUE(
271  RectNear(result_coverage.value(), Rect::MakeLTRB(99, 199, 201, 301)));
272  }
273  }
274 }
275 
277  RenderCoverageMatchesGetCoverageRotated) {
278  std::shared_ptr<Texture> texture = MakeTexture(ISize(400, 300));
279  fml::StatusOr<Scalar> sigma_radius_1 =
280  CalculateSigmaForBlurRadius(1.0, Matrix());
281  auto contents = std::make_unique<GaussianBlurFilterContents>(
282  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
283  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
284  contents->SetInputs({FilterInput::Make(texture)});
285  std::shared_ptr<ContentContext> renderer = GetContentContext();
286 
287  Entity entity;
288  // Rotate around the top left corner, then push it over to (100, 100).
289  entity.SetTransform(Matrix::MakeTranslation({400, 100, 0}) *
291  std::optional<Entity> result =
292  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
293  EXPECT_TRUE(result.has_value());
294  if (result.has_value()) {
295  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
296  std::optional<Rect> result_coverage = result.value().GetCoverage();
297  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
298  EXPECT_TRUE(result_coverage.has_value());
299  EXPECT_TRUE(contents_coverage.has_value());
300  if (result_coverage.has_value() && contents_coverage.has_value()) {
301  EXPECT_TRUE(RectNear(contents_coverage.value(),
302  Rect::MakeLTRB(99, 99, 401, 501)));
303  EXPECT_TRUE(
304  RectNear(result_coverage.value(), Rect::MakeLTRB(99, 99, 401, 501)));
305  }
306  }
307 }
308 
310  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
311  auto filter_input = FilterInput::Make(texture);
312  Entity entity;
314  filter_input, entity, Rect::MakeSize(ISize(100, 100)), ISize(100, 100));
315  std::optional<Rect> uvs_bounds = Rect::MakePointBounds(uvs);
316  EXPECT_TRUE(uvs_bounds.has_value());
317  if (uvs_bounds.has_value()) {
318  EXPECT_TRUE(RectNear(uvs_bounds.value(), Rect::MakeXYWH(0, 0, 1, 1)));
319  }
320 }
321 
322 TEST_P(GaussianBlurFilterContentsTest, TextureContentsWithDestinationRect) {
323  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
324  auto texture_contents = std::make_shared<TextureContents>();
325  texture_contents->SetSourceRect(Rect::MakeSize(texture->GetSize()));
326  texture_contents->SetTexture(texture);
327  texture_contents->SetDestinationRect(Rect::MakeXYWH(
328  50, 40, texture->GetSize().width, texture->GetSize().height));
329 
330  fml::StatusOr<Scalar> sigma_radius_1 =
331  CalculateSigmaForBlurRadius(1.0, Matrix());
332  auto contents = std::make_unique<GaussianBlurFilterContents>(
333  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
334  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
335  contents->SetInputs({FilterInput::Make(texture_contents)});
336  std::shared_ptr<ContentContext> renderer = GetContentContext();
337 
338  Entity entity;
339  std::optional<Entity> result =
340  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
341  EXPECT_TRUE(result.has_value());
342  if (result.has_value()) {
343  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
344  std::optional<Rect> result_coverage = result.value().GetCoverage();
345  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
346  EXPECT_TRUE(result_coverage.has_value());
347  EXPECT_TRUE(contents_coverage.has_value());
348  if (result_coverage.has_value() && contents_coverage.has_value()) {
349  EXPECT_TRUE(RectNear(result_coverage.value(), contents_coverage.value()));
350  EXPECT_TRUE(RectNear(result_coverage.value(),
351  Rect::MakeLTRB(49.f, 39.f, 151.f, 141.f)));
352  }
353  }
354 }
355 
357  TextureContentsWithDestinationRectScaled) {
358  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
359  auto texture_contents = std::make_shared<TextureContents>();
360  texture_contents->SetSourceRect(Rect::MakeSize(texture->GetSize()));
361  texture_contents->SetTexture(texture);
362  texture_contents->SetDestinationRect(Rect::MakeXYWH(
363  50, 40, texture->GetSize().width, texture->GetSize().height));
364 
365  fml::StatusOr<Scalar> sigma_radius_1 =
366  CalculateSigmaForBlurRadius(1.0, Matrix());
367  auto contents = std::make_unique<GaussianBlurFilterContents>(
368  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
369  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
370  contents->SetInputs({FilterInput::Make(texture_contents)});
371  std::shared_ptr<ContentContext> renderer = GetContentContext();
372 
373  Entity entity;
374  entity.SetTransform(Matrix::MakeScale({2.0, 2.0, 1.0}));
375  std::optional<Entity> result =
376  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
377  EXPECT_TRUE(result.has_value());
378  if (result.has_value()) {
379  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
380  std::optional<Rect> result_coverage = result.value().GetCoverage();
381  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
382  EXPECT_TRUE(result_coverage.has_value());
383  EXPECT_TRUE(contents_coverage.has_value());
384  if (result_coverage.has_value() && contents_coverage.has_value()) {
385  EXPECT_TRUE(RectNear(result_coverage.value(), contents_coverage.value()));
386  EXPECT_TRUE(RectNear(contents_coverage.value(),
387  Rect::MakeLTRB(98.f, 78.f, 302.f, 282.f)));
388  }
389  }
390 }
391 
392 TEST_P(GaussianBlurFilterContentsTest, TextureContentsWithEffectTransform) {
393  Matrix effect_transform = Matrix::MakeScale({2.0, 2.0, 1.0});
394  std::shared_ptr<Texture> texture = MakeTexture(ISize(100, 100));
395  auto texture_contents = std::make_shared<TextureContents>();
396  texture_contents->SetSourceRect(Rect::MakeSize(texture->GetSize()));
397  texture_contents->SetTexture(texture);
398  texture_contents->SetDestinationRect(Rect::MakeXYWH(
399  50, 40, texture->GetSize().width, texture->GetSize().height));
400 
401  fml::StatusOr<Scalar> sigma_radius_1 =
402  CalculateSigmaForBlurRadius(1.0, effect_transform);
403  ASSERT_TRUE(sigma_radius_1.ok());
404  auto contents = std::make_unique<GaussianBlurFilterContents>(
405  sigma_radius_1.value(), sigma_radius_1.value(), Entity::TileMode::kDecal,
406  FilterContents::BlurStyle::kNormal, /*mask_geometry=*/nullptr);
407  contents->SetInputs({FilterInput::Make(texture_contents)});
408  contents->SetEffectTransform(effect_transform);
409  std::shared_ptr<ContentContext> renderer = GetContentContext();
410 
411  Entity entity;
412  std::optional<Entity> result =
413  contents->GetEntity(*renderer, entity, /*coverage_hint=*/{});
414  EXPECT_TRUE(result.has_value());
415  if (result.has_value()) {
416  EXPECT_EQ(result.value().GetBlendMode(), BlendMode::kSourceOver);
417  std::optional<Rect> result_coverage = result.value().GetCoverage();
418  std::optional<Rect> contents_coverage = contents->GetCoverage(entity);
419  EXPECT_TRUE(result_coverage.has_value());
420  EXPECT_TRUE(contents_coverage.has_value());
421  if (result_coverage.has_value() && contents_coverage.has_value()) {
422  EXPECT_TRUE(RectNear(result_coverage.value(), contents_coverage.value()));
423  EXPECT_TRUE(RectNear(contents_coverage.value(),
424  Rect::MakeXYWH(49.f, 39.f, 102.f, 102.f)));
425  }
426  }
427 }
428 
429 TEST(GaussianBlurFilterContentsTest, CalculateSigmaForBlurRadius) {
430  Scalar sigma = 1.0;
433  fml::StatusOr<Scalar> derived_sigma =
434  CalculateSigmaForBlurRadius(radius, Matrix());
435  ASSERT_TRUE(derived_sigma.ok());
436  EXPECT_NEAR(sigma, derived_sigma.value(), 0.01f);
437 }
438 
440  BlurParameters parameters = {.blur_uv_offset = Point(1, 0),
441  .blur_sigma = 1,
442  .blur_radius = 5,
443  .step_size = 1};
444  KernelPipeline::FragmentShader::KernelSamples samples =
445  GenerateBlurInfo(parameters);
446  EXPECT_EQ(samples.sample_count, 9);
447 
448  // Coefficients should add up to 1.
449  Scalar tally = 0;
450  for (int i = 0; i < samples.sample_count; ++i) {
451  tally += samples.samples[i].coefficient;
452  }
453  EXPECT_FLOAT_EQ(tally, 1.0f);
454 
455  // Verify the shape of the curve.
456  for (int i = 0; i < 4; ++i) {
457  EXPECT_FLOAT_EQ(samples.samples[i].coefficient,
458  samples.samples[8 - i].coefficient);
459  EXPECT_TRUE(samples.samples[i + 1].coefficient >
460  samples.samples[i].coefficient);
461  }
462 }
463 
464 TEST(GaussianBlurFilterContentsTest, LerpHackKernelSamplesSimple) {
465  KernelPipeline::FragmentShader::KernelSamples kernel_samples = {
466  .sample_count = 5,
467  .samples =
468  {
469  {
470  .uv_offset = Vector2(-2, 0),
471  .coefficient = 0.1f,
472  },
473  {
474  .uv_offset = Vector2(-1, 0),
475  .coefficient = 0.2f,
476  },
477  {
478  .uv_offset = Vector2(0, 0),
479  .coefficient = 0.4f,
480  },
481  {
482  .uv_offset = Vector2(1, 0),
483  .coefficient = 0.2f,
484  },
485  {
486  .uv_offset = Vector2(2, 0),
487  .coefficient = 0.1f,
488  },
489  },
490  };
491 
492  KernelPipeline::FragmentShader::KernelSamples fast_kernel_samples =
493  LerpHackKernelSamples(kernel_samples);
494  EXPECT_EQ(fast_kernel_samples.sample_count, 3);
495 
496  KernelPipeline::FragmentShader::KernelSample* samples =
497  kernel_samples.samples;
498  KernelPipeline::FragmentShader::KernelSample* fast_samples =
499  fast_kernel_samples.samples;
500 
501  //////////////////////////////////////////////////////////////////////////////
502  // Check output kernel.
503 
504  EXPECT_FLOAT_EQ(fast_samples[0].uv_offset.x, -1.3333333);
505  EXPECT_FLOAT_EQ(fast_samples[0].uv_offset.y, 0);
506  EXPECT_FLOAT_EQ(fast_samples[0].coefficient, 0.3);
507  EXPECT_FLOAT_EQ(fast_samples[1].uv_offset.x, 0);
508  EXPECT_FLOAT_EQ(fast_samples[1].uv_offset.y, 0);
509  EXPECT_FLOAT_EQ(fast_samples[1].coefficient, 0.4);
510  EXPECT_FLOAT_EQ(fast_samples[2].uv_offset.x, 1.3333333);
511  EXPECT_FLOAT_EQ(fast_samples[2].uv_offset.y, 0);
512  EXPECT_FLOAT_EQ(fast_samples[2].coefficient, 0.3);
513 
514  //////////////////////////////////////////////////////////////////////////////
515  // Check output of fast kernel versus original kernel.
516 
517  Scalar data[5] = {0.25, 0.5, 0.5, 1.0, 0.2};
518  Scalar original_output =
519  samples[0].coefficient * data[0] + samples[1].coefficient * data[1] +
520  samples[2].coefficient * data[2] + samples[3].coefficient * data[3] +
521  samples[4].coefficient * data[4];
522 
523  auto lerp = [](const Point& point, Scalar left, Scalar right) {
524  Scalar int_part;
525  Scalar fract = fabsf(modf(point.x, &int_part));
526  if (point.x < 0) {
527  return left * fract + right * (1.0 - fract);
528  } else {
529  return left * (1.0 - fract) + right * fract;
530  }
531  };
532  Scalar fast_output =
533  /*1st*/ lerp(fast_samples[0].uv_offset, data[0], data[1]) *
534  fast_samples[0].coefficient +
535  /*2nd*/ data[2] * fast_samples[1].coefficient +
536  /*3rd*/ lerp(fast_samples[2].uv_offset, data[3], data[4]) *
537  fast_samples[2].coefficient;
538 
539  EXPECT_NEAR(original_output, fast_output, 0.01);
540 }
541 
542 TEST(GaussianBlurFilterContentsTest, LerpHackKernelSamplesComplex) {
543  Scalar sigma = 10.0f;
544  int32_t blur_radius = static_cast<int32_t>(
546  BlurParameters parameters = {.blur_uv_offset = Point(1, 0),
547  .blur_sigma = sigma,
548  .blur_radius = blur_radius,
549  .step_size = 1};
550  KernelPipeline::FragmentShader::KernelSamples kernel_samples =
551  GenerateBlurInfo(parameters);
552  EXPECT_EQ(kernel_samples.sample_count, 33);
553  KernelPipeline::FragmentShader::KernelSamples fast_kernel_samples =
554  LerpHackKernelSamples(kernel_samples);
555  EXPECT_EQ(fast_kernel_samples.sample_count, 17);
556  float data[33];
557  srand(0);
558  for (int i = 0; i < 33; i++) {
559  data[i] = 255.0 * static_cast<double>(IMPELLER_RAND()) / RAND_MAX;
560  }
561 
562  auto sampler = [data](Point point) -> Scalar {
563  FML_CHECK(point.y == 0.0f);
564  FML_CHECK(point.x >= -16);
565  FML_CHECK(point.x <= 16);
566  Scalar fint_part;
567  Scalar fract = fabsf(modf(point.x, &fint_part));
568  if (fract == 0) {
569  int32_t int_part = static_cast<int32_t>(fint_part) + 16;
570  return data[int_part];
571  } else {
572  int32_t left = static_cast<int32_t>(floor(point.x)) + 16;
573  int32_t right = static_cast<int32_t>(ceil(point.x)) + 16;
574  if (point.x < 0) {
575  return fract * data[left] + (1.0 - fract) * data[right];
576  } else {
577  return (1.0 - fract) * data[left] + fract * data[right];
578  }
579  }
580  };
581 
582  Scalar output = 0.0;
583  for (int i = 0; i < kernel_samples.sample_count; ++i) {
584  auto sample = kernel_samples.samples[i];
585  output += sample.coefficient * sampler(sample.uv_offset);
586  }
587 
588  Scalar fast_output = 0.0;
589  for (int i = 0; i < fast_kernel_samples.sample_count; ++i) {
590  auto sample = fast_kernel_samples.samples[i];
591  fast_output += sample.coefficient * sampler(sample.uv_offset);
592  }
593 
594  EXPECT_NEAR(output, fast_output, 0.1);
595 }
596 
597 } // namespace testing
598 } // namespace impeller
impeller::Scalar
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