Add a test for loading gltf with external textures

graphics/src/AssimpLoader_TEST.cc

@@ -620,6 +620,30 @@ TEST_F(AssimpLoader, LoadGlTF2Box)
   EXPECT_DOUBLE_EQ(mat->Transparency(), 0.0);
 }
 
+/////////////////////////////////////////////////
+// Open a gltf mesh with an external texture
+TEST_F(AssimpLoader, LoadGlTF2BoxExternalTexture)
+{
+  common::AssimpLoader loader;
+  common::Mesh *mesh = loader.Load(
+      common::testing::TestFile("data/gltf", "PurpleCube.gltf"));
+
+  EXPECT_STREQ("unknown", mesh->Name().c_str());
+
+  // Make sure we can read the submesh name
+  EXPECT_STREQ("PurpleCube", mesh->SubMeshByIndex(0).lock()->Name().c_str());
+
+  EXPECT_EQ(mesh->MaterialCount(), 1u);
+
+  const common::MaterialPtr mat = mesh->MaterialByIndex(0u);
+  ASSERT_TRUE(mat.get());
+  // No data (it is a file), but a populated filename
+  EXPECT_EQ(nullptr, mat->TextureData());
+  auto testTextureFile =
+    common::testing::TestFile("data/gltf", "PurpleCube_Diffuse.png");
+  EXPECT_EQ(testTextureFile, mat->TextureImage());
+}
+
 /////////////////////////////////////////////////
 // Use a fully featured glb test asset, including PBR textures, emissive maps
 // embedded textures, lightmaps, animations to test advanced glb features

test/data/gltf/PurpleCube.gltf

@@ -0,0 +1,133 @@
+{
+    "asset" : {
+        "generator" : "Khronos glTF Blender I/O v1.8.19",
+        "version" : "2.0"
+    },
+    "scene" : 0,
+    "scenes" : [
+        {
+            "name" : "Scene",
+            "nodes" : [
+                0
+            ]
+        }
+    ],
+    "nodes" : [
+        {
+            "mesh" : 0,
+            "name" : "PurpleCube"
+        }
+    ],
+    "materials" : [
+        {
+            "doubleSided" : true,
+            "name" : "PurpleCube",
+            "pbrMetallicRoughness" : {
+                "baseColorTexture" : {
+                    "index" : 0
+                },
+                "metallicFactor" : 0,
+                "roughnessFactor" : 0.5
+            }
+        }
+    ],
+    "meshes" : [
+        {
+            "name" : "PurpleCube",
+            "primitives" : [
+                {
+                    "attributes" : {
+                        "POSITION" : 0,
+                        "NORMAL" : 1,
+                        "TEXCOORD_0" : 2
+                    },
+                    "indices" : 3,
+                    "material" : 0
+                }
+            ]
+        }
+    ],
+    "textures" : [
+        {
+            "sampler" : 0,
+            "source" : 0
+        }
+    ],
+    "images" : [
+        {
+            "mimeType" : "image/png",
+            "name" : "PurpleCube_Diffuse",
+            "uri" : "PurpleCube_Diffuse.png"
+        }
+    ],
+    "accessors" : [
+        {
+            "bufferView" : 0,
+            "componentType" : 5126,
+            "count" : 24,
+            "max" : [
+                1,
+                1,
+                2
+            ],
+            "min" : [
+                -1,
+                -1,
+                0
+            ],
+            "type" : "VEC3"
+        },
+        {
+            "bufferView" : 1,
+            "componentType" : 5126,
+            "count" : 24,
+            "type" : "VEC3"
+        },
+        {
+            "bufferView" : 2,
+            "componentType" : 5126,
+            "count" : 24,
+            "type" : "VEC2"
+        },
+        {
+            "bufferView" : 3,
+            "componentType" : 5123,
+            "count" : 36,
+            "type" : "SCALAR"
+        }
+    ],
+    "bufferViews" : [
+        {
+            "buffer" : 0,
+            "byteLength" : 288,
+            "byteOffset" : 0
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 288,
+            "byteOffset" : 288
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 192,
+            "byteOffset" : 576
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 72,
+            "byteOffset" : 768
+        }
+    ],
+    "samplers" : [
+        {
+            "magFilter" : 9729,
+            "minFilter" : 9987
+        }
+    ],
+    "buffers" : [
+        {
+            "byteLength" : 840,
+            "uri" : "PurpleCube.bin"
+        }
+    ]
+}