Extend AssimpLoader to parse material transmission factor (#577)

Signed-off-by: Ian Chen <[email protected]> Co-authored-by: Michael Carroll <[email protected]>
gazebosim · Mar 4, 2024 · b3ba7ab · b3ba7ab
1 parent 3571cb4
commit b3ba7ab
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Showing 4 changed files with 53 additions and 4 deletions.
diff --git a/graphics/src/AssimpLoader.cc b/graphics/src/AssimpLoader.cc
@@ -357,8 +357,26 @@ MaterialPtr AssimpLoader::Implementation::CreateMaterial(
  }
  float opacity = 1.0;
  ret = assimpMat->Get(AI_MATKEY_OPACITY, opacity);
- mat->SetTransparency(1.0 - opacity);
- mat->SetBlendFactors(opacity, 1.0 - opacity);
+ if (ret == AI_SUCCESS)
+ {
+ mat->SetTransparency(1.0 - opacity);
+ mat->SetBlendFactors(opacity, 1.0 - opacity);
+ }
+
+#ifndef GZ_ASSIMP_PRE_5_1_0
+ // basic support for transmission - currently just overrides opacity
+ // \todo(iche033) The transmission factor can be used with volume
+ // material extension to simulate effects like refraction
+ // so consider also extending support for other properties like
+ // AI_MATKEY_VOLUME_THICKNESS_FACTOR
+ float transmission = 0.0;
+ ret = assimpMat->Get(AI_MATKEY_TRANSMISSION_FACTOR, transmission);
+ if (ret == AI_SUCCESS)
+ {
+ mat->SetTransparency(transmission);
+ }
+#endif
+
  // TODO(luca) more than one texture, Gazebo assumes UV index 0
  Pbr pbr;
  aiString texturePath(_path.c_str());
@@ -593,6 +611,7 @@ std::string AssimpLoader::Implementation::GenerateTextureName(
  "_" + _type;
 }
 
+//////////////////////////////////////////////////
 SubMesh AssimpLoader::Implementation::CreateSubMesh(
  const aiMesh* _assimpMesh, const math::Matrix4d& _transform) const
 {

diff --git a/graphics/src/AssimpLoader_TEST.cc b/graphics/src/AssimpLoader_TEST.cc
@@ -665,6 +665,30 @@ TEST_F(AssimpLoader, LoadGlTF2BoxExternalTexture)
  delete mesh;
 }
 
+/////////////////////////////////////////////////
+// Open a gltf mesh with transmission extension
+TEST_F(AssimpLoader, LoadGlTF2BoxTransmission)
+{
+#ifndef GZ_ASSIMP_PRE_5_1_0
+ common::AssimpLoader loader;
+ common::Mesh *mesh = loader.Load(
+ common::testing::TestFile("data", "box_transmission.glb"));
+
+ EXPECT_STREQ("unknown", mesh->Name().c_str());
+
+ // Make sure we can read the submesh name
+ EXPECT_STREQ("Cube", mesh->SubMeshByIndex(0).lock()->Name().c_str());
+
+ EXPECT_EQ(mesh->MaterialCount(), 1u);
+
+ const common::MaterialPtr mat = mesh->MaterialByIndex(0u);
+ ASSERT_TRUE(mat.get());
+ // transmission currently modeled as transparency
+ EXPECT_FLOAT_EQ(0.1, mat->Transparency());
+ delete mesh;
+#endif
+}
+
 /////////////////////////////////////////////////
 // This test loads a box glb mesh with embedded compressed jpeg texture
 TEST_F(AssimpLoader, LoadGlTF2BoxWithJPEGTexture)

diff --git a/graphics/src/CMakeLists.txt b/graphics/src/CMakeLists.txt
@@ -29,16 +29,22 @@ gz_build_tests(
 )
 
 # Assimp doesn't offer preprocessor version, use cmake to set a compatibility
-# mode for versions below 5.2.0
+# mode for versions below 5.2.0 and 5.1.0
 if(${GzAssimp_VERSION} STRLESS "5.2.0")
  message("Warning, assimp below 5.2.0 detected, setting compatibility mode")
  target_compile_definitions(${graphics_target} PRIVATE GZ_ASSIMP_PRE_5_2_0)
  if(TARGET UNIT_AssimpLoader_TEST)
  target_compile_definitions(UNIT_AssimpLoader_TEST PRIVATE GZ_ASSIMP_PRE_5_2_0)
  endif()
+ if(${GzAssimp_VERSION} STRLESS "5.1.0")
+ message("Warning, assimp below 5.1.0 detected, setting compatibility mode")
+ target_compile_definitions(${graphics_target} PRIVATE GZ_ASSIMP_PRE_5_1_0)
+ if(TARGET UNIT_AssimpLoader_TEST)
+ target_compile_definitions(UNIT_AssimpLoader_TEST PRIVATE GZ_ASSIMP_PRE_5_1_0)
+ endif()
+ endif()
 endif()
 
-
 if(USE_EXTERNAL_TINYXML2)
 
  # If we are using an external copy of tinyxml2, add its imported target

diff --git a/test/data/box_transmission.glb b/test/data/box_transmission.glb