obj: reduce vertex colors to 4 decimal places, reenable tests

OBJ vertex color related tests were not producing identical results
across various platforms, primarily due to sRGB<->Linear color space
conversions.

While D15193 has just made the color space conversion accuracy match
much closer between platforms, it's still not 100% the same.

This change reduces the amount of decimal places used for exporting
vertex colors, to 4 digits (down from 6). Vertex normals were
already always printed with 4 digits, and colors are conceptually
similar (usually 0..1 range etc.).

This makes the vertex color tests pass again, so re-enable them
after adjusting to 4 decimals expectations.

3 files changed, 6 insertions, 10 deletions

diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
index 157d7760307..5413c9969e3 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
@@ -132,7 +132,7 @@ constexpr FormattingSyntax syntax_elem_to_formatting(const eOBJSyntaxElement key
       return {"v {:.6f} {:.6f} {:.6f}\n", 3, is_type_float<T...>};
     }
     case eOBJSyntaxElement::vertex_coords_color: {
-      return {"v {:.6f} {:.6f} {:.6f} {:.6f} {:.6f} {:.6f}\n", 6, is_type_float<T...>};
+      return {"v {:.6f} {:.6f} {:.6f} {:.4f} {:.4f} {:.4f}\n", 6, is_type_float<T...>};
     }
     case eOBJSyntaxElement::uv_vertex_coords: {
       return {"vt {:.6f} {:.6f}\n", 2, is_type_float<T...>};
diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
index fea74c2fd90..6aec848573f 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -436,8 +436,6 @@ TEST_F(obj_exporter_regression_test, cubes_positioned)
                                _export.params);
 }
 
-/* Disabled until sRGB<->Linear conversion produces close enough results between
- * SSE2 and non-SSE2.
 TEST_F(obj_exporter_regression_test, cubes_vertex_colors)
 {
   OBJExportParamsDefault _export;
@@ -450,7 +448,6 @@ TEST_F(obj_exporter_regression_test, cubes_vertex_colors)
                                "",
                                _export.params);
 }
-*/
 
 TEST_F(obj_exporter_regression_test, cubes_with_textures_strip)
 {
@@ -510,7 +507,7 @@ TEST_F(obj_exporter_regression_test, all_objects)
   _export.params.forward_axis = IO_AXIS_Y;
   _export.params.up_axis = IO_AXIS_Z;
   _export.params.export_smooth_groups = true;
-  //_export.params.export_colors = true;
+  _export.params.export_colors = true;
   compare_obj_export_to_golden("io_tests/blend_scene/all_objects.blend",
                                "io_tests/obj/all_objects.obj",
                                "io_tests/obj/all_objects.mtl",
diff --git a/source/blender/io/wavefront_obj/tests/obj_importer_tests.cc b/source/blender/io/wavefront_obj/tests/obj_importer_tests.cc
index efdd8839615..b67adbc9753 100644
--- a/source/blender/io/wavefront_obj/tests/obj_importer_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_importer_tests.cc
@@ -453,7 +453,8 @@ TEST_F(obj_importer_test, import_all_objects)
        float3(13, 1, -1),
        float3(11, 1, 1),
        float3(0, 0, 1),
-       float2(0, 0)},
+       float2(0, 0),
+       float4(0.0f, 0.002125f, 1.0f, 1.0f)},
       {"OBUVCube",
        OB_MESH,
        8,
@@ -509,7 +510,6 @@ TEST_F(obj_importer_test, import_all_objects)
   import_and_check("all_objects.obj", expect, std::size(expect), 7);
 }
 
-/*
 TEST_F(obj_importer_test, import_cubes_vertex_colors)
 {
   Expectation expect[] = {
@@ -524,7 +524,7 @@ TEST_F(obj_importer_test, import_cubes_vertex_colors)
        float3(-1.0f, -1.0f, 1.0f),
        float3(0, 0, 0),
        float2(0, 0),
-       float4(0.846873f, 0.027321f, 0.982251f, 1.0f)},
+       float4(0.846873f, 0.027321f, 0.982123f, 1.0f)},
       {"OBCubeVertexFloat",
        OB_MESH,
        8,
@@ -535,7 +535,7 @@ TEST_F(obj_importer_test, import_cubes_vertex_colors)
        float3(1.392028f, -1.0f, 1.0f),
        float3(0, 0, 0),
        float2(0, 0),
-       float4(49.99558f, 0.027321f, 0.982251f, 1.0f)},
+       float4(49.99467f, 0.027321f, 0.982123f, 1.0f)},
       {"OBCubeCornerByte",
        OB_MESH,
        8,
@@ -580,7 +580,6 @@ TEST_F(obj_importer_test, import_cubes_vertex_colors)
   };
   import_and_check("cubes_vertex_colors.obj", expect, std::size(expect), 0);
 }
- */
 
 TEST_F(obj_importer_test, import_cubes_vertex_colors_mrgb)
 {