From 2637bbf0164cd22a9918896d81ef295cc55272dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cle=CC=81ment=20Foucault?= <foucault.clem@gmail.com>
Date: Sun, 3 Sep 2023 13:38:21 +0200
Subject: [PATCH] EEVEE-Next: Add LUT test

This avoid the generation code to become desync with
the precomputed tabled.

This is also a good way to test any changes to them.
---
 source/blender/draw/tests/eevee_test.cc | 21 +++++++++++++++++++++
 tests/gtests/testing/testing.h          | 12 ++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/source/blender/draw/tests/eevee_test.cc b/source/blender/draw/tests/eevee_test.cc
index e5d3ad4240f..b05634e619d 100644
--- a/source/blender/draw/tests/eevee_test.cc
+++ b/source/blender/draw/tests/eevee_test.cc
@@ -16,6 +16,7 @@
 #include "draw_shader.h"
 #include "draw_testing.hh"
 #include "engines/eevee_next/eevee_instance.hh"
+#include "engines/eevee_next/eevee_lut.hh"
 
 namespace blender::draw {
 
@@ -1440,4 +1441,24 @@ static void test_eevee_surfel_list()
 }
 DRAW_TEST(eevee_surfel_list)
 
+static void test_eevee_lut_gen()
+{
+  GPU_render_begin();
+
+  Manager manager;
+
+  /* Check if LUT generation matches the header version. */
+  auto bsdf_ggx_gen = LookUpTable(manager, LUT_GGX_BRDF_SPLIT_SUM, {64, 64, 1}).data<float2>();
+  auto btdf_ggx_gen = LookUpTable(manager, LUT_GGX_BTDF_SPLIT_SUM, {64, 64, 16}).data<float2>();
+
+  Span<float2> bsdf_ggx_lut(reinterpret_cast<const float2 *>(bsdf_split_sum_ggx), 64 * 64);
+  Span<float2> btdf_ggx_lut(reinterpret_cast<const float2 *>(btdf_split_sum_ggx), 64 * 64 * 16);
+
+  EXPECT_NEAR_ARRAY_ND(bsdf_ggx_lut.data(), bsdf_ggx_gen.data(), bsdf_ggx_gen.size(), 2, 5e-4f);
+  EXPECT_NEAR_ARRAY_ND(btdf_ggx_lut.data(), btdf_ggx_gen.data(), btdf_ggx_gen.size(), 2, 5e-4f);
+
+  GPU_render_end();
+}
+DRAW_TEST(eevee_lut_gen)
+
 }  // namespace blender::draw
diff --git a/tests/gtests/testing/testing.h b/tests/gtests/testing/testing.h
index 8f30d777eef..5b0a73ff253 100644
--- a/tests/gtests/testing/testing.h
+++ b/tests/gtests/testing/testing.h
@@ -153,6 +153,18 @@ inline void EXPECT_EQ_ARRAY_ND(const T *expected, const T *actual, const size_t
   }
 }
 
+template<typename T, typename U>
+inline void EXPECT_NEAR_ARRAY_ND(
+    const T *expected, const T *actual, const size_t N, const size_t D, const U tolerance)
+{
+  for (size_t i = 0; i < N; ++i) {
+    for (size_t j = 0; j < D; ++j) {
+      EXPECT_NEAR(expected[i][j], actual[i][j], tolerance)
+          << "Element mismatch at index " << i << ", component index " << j;
+    }
+  }
+}
+
 #ifdef _WIN32
 #  define ABORT_PREDICATE ::testing::ExitedWithCode(3)
 #else