AssimpImporter: implement tangent/bitangent import.

mosra · Mar 28, 2020 · 1ed63e0 · 1ed63e0
1 parent 82d9977
commit 1ed63e0
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Showing 5 changed files with 67 additions and 18 deletions.
diff --git a/doc/changelog-plugins.dox b/doc/changelog-plugins.dox
@@ -38,6 +38,7 @@ namespace Magnum {
     consistent with @ref Trade::TinyGltfImporter "TinyGltfImporter" behavior
     (see [mosra/magnum-plugins#68](https://github.com/mosra/magnum-plugins/pull/68)
     and [mosra/magnum-plugins#81](https://github.com/mosra/magnum-plugins/pull/81))
+-   Tangent and bitangent import in @ref Trade::AssimpImporter "AssimpImporter"
 -   Vertex color, normal and texture coordinate import in
     @ref Trade::StanfordImporter "StanfordImporter", colors and normals are
     supported per-face as well

diff --git a/src/MagnumPlugins/AssimpImporter/AssimpImporter.cpp b/src/MagnumPlugins/AssimpImporter/AssimpImporter.cpp
@@ -547,6 +547,11 @@ Containers::Optional<MeshData> AssimpImporter::doMesh(const UnsignedInt id, Unsi
         ++attributeCount;
         stride += sizeof(Vector3);
     }
+    /* Assimp provides either none or both, never just one of these */
+    if(mesh->HasTangentsAndBitangents()) {
+        attributeCount += 2;
+        stride += 2*sizeof(Vector3);
+    }
     for(std::size_t layer = 0; layer < mesh->GetNumUVChannels(); ++layer) {
         if(mesh->mNumUVComponents[layer] != 2) {
             Warning() << "Trade::AssimpImporter::mesh(): skipping texture coordinate layer" << layer << "which has" << mesh->mNumUVComponents[layer] << "components per coordinate. Only two dimensional texture coordinates are supported.";
@@ -590,6 +595,28 @@ Containers::Optional<MeshData> AssimpImporter::doMesh(const UnsignedInt id, Unsi
         attributeOffset += sizeof(Vector3);
     }
 
+    /* Tangents + bitangents, if any. Assimp always provides either none or
+       both, never just one of these. */
+    if(mesh->HasTangentsAndBitangents()) {
+        Containers::StridedArrayView1D<Vector3> tangents{vertexData,
+            reinterpret_cast<Vector3*>(vertexData + attributeOffset),
+            vertexCount, stride};
+        Utility::copy(Containers::arrayView(reinterpret_cast<Vector3*>(mesh->mTangents), mesh->mNumVertices), tangents);
+
+        attributeData[attributeIndex++] = MeshAttributeData{
+            MeshAttribute::Tangent, tangents};
+        attributeOffset += sizeof(Vector3);
+
+        Containers::StridedArrayView1D<Vector3> bitangents{vertexData,
+            reinterpret_cast<Vector3*>(vertexData + attributeOffset),
+            vertexCount, stride};
+        Utility::copy(Containers::arrayView(reinterpret_cast<Vector3*>(mesh->mBitangents), mesh->mNumVertices), bitangents);
+
+        attributeData[attributeIndex++] = MeshAttributeData{
+            MeshAttribute::Bitangent, bitangents};
+        attributeOffset += sizeof(Vector3);
+    }
+
     /* Texture coordinates */
     /** @todo only first uv layer (or "channel") supported) */
     for(std::size_t layer = 0; layer < mesh->GetNumUVChannels(); ++layer) {

diff --git a/src/MagnumPlugins/AssimpImporter/AssimpImporter.h b/src/MagnumPlugins/AssimpImporter/AssimpImporter.h
@@ -230,11 +230,14 @@ Import of animation data is not supported at the moment.
     "skeleton visualizer" mesh if the file has no mesh data. For others (such
     as glTF) not.
 -   The importer follows types used by Assimp, thus indices are always
-    @ref MeshIndexType::UnsignedInt, positions and normals are always imported
-    as @ref VertexFormat::Vector3, texture coordinates as
-    @ref VertexFormat::Vector2 and colors as @ref VertexFormat::Vector4. In
-    other words, everything gets expanded by Assimp to floats, even if the
-    original file might be using different types.
+    @ref MeshIndexType::UnsignedInt, positions, normals, tangents and
+    bitangents are always imported as @ref VertexFormat::Vector3, texture
+    coordinates as @ref VertexFormat::Vector2 and colors as
+    @ref VertexFormat::Vector4. In other words, everything gets expanded by
+    Assimp to floats, even if the original file might be using different types.
+-   The imported model always has either both @ref MeshAttribute::Tangent
+    @ref MeshAttribute::Bitangent or neither of them, tangents are always
+    three-component with binormals separate.
 -   Multi-mesh nodes and multi-primitive meshes are loaded as follows,
     consistently with the behavior of @link TinyGltfImporter @endlink:
     -   Multi-primitive meshes are split by Assimp into individual meshes

diff --git a/src/MagnumPlugins/AssimpImporter/Test/AssimpImporterTest.cpp b/src/MagnumPlugins/AssimpImporter/Test/AssimpImporterTest.cpp
@@ -617,7 +617,7 @@ void AssimpImporterTest::mesh() {
         Containers::arrayView<UnsignedInt>({0, 1, 2}),
         TestSuite::Compare::Container);
 
-    CORRADE_COMPARE(mesh->attributeCount(), 4);
+    CORRADE_COMPARE(mesh->attributeCount(), 6);
     CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::Position), 1);
     CORRADE_COMPARE_AS(mesh->attribute<Vector3>(MeshAttribute::Position),
         Containers::arrayView<Vector3>({
@@ -628,6 +628,16 @@ void AssimpImporterTest::mesh() {
         Containers::arrayView<Vector3>({
             {0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 1.0f}
         }), TestSuite::Compare::Container);
+    CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::Tangent), 1);
+    CORRADE_COMPARE_AS(mesh->attribute<Vector3>(MeshAttribute::Tangent),
+        Containers::arrayView<Vector3>({
+            {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 0.0f},
+        }), TestSuite::Compare::Container);
+    CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::Bitangent), 1);
+    CORRADE_COMPARE_AS(mesh->attribute<Vector3>(MeshAttribute::Bitangent),
+        Containers::arrayView<Vector3>({
+            {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f}, {0.0f, 1.0f, 0.0f},
+        }), TestSuite::Compare::Container);
     CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::TextureCoordinates), 1);
     CORRADE_COMPARE_AS(mesh->attribute<Vector2>(MeshAttribute::TextureCoordinates),
         Containers::arrayView<Vector2>({
@@ -1219,8 +1229,8 @@ void AssimpImporterTest::fileCallback() {
     CORRADE_VERIFY(importer->openFile("not/a/path/mesh.dae"));
     CORRADE_COMPARE(importer->meshCount(), 1);
 
-    /* Same as in mesh(), not testing colors because of the assimp bugs that
-       need to be worked around */
+    /* Same as in mesh(), testing just the basics, no need to repeat everything
+       here */
     Containers::Optional<MeshData> mesh = importer->mesh(0);
     CORRADE_VERIFY(mesh);
     CORRADE_COMPARE(mesh->primitive(), MeshPrimitive::Triangles);
@@ -1230,7 +1240,7 @@ void AssimpImporterTest::fileCallback() {
         Containers::arrayView<UnsignedInt>({0, 1, 2}),
         TestSuite::Compare::Container);
 
-    CORRADE_COMPARE(mesh->attributeCount(), 4);
+    CORRADE_COMPARE(mesh->attributeCount(), 6);
     CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::Position), 1);
     CORRADE_COMPARE_AS(mesh->attribute<Vector3>(MeshAttribute::Position),
         Containers::arrayView<Vector3>({
@@ -1241,11 +1251,6 @@ void AssimpImporterTest::fileCallback() {
         Containers::arrayView<Vector3>({
             {0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 1.0f}
         }), TestSuite::Compare::Container);
-    CORRADE_COMPARE(mesh->attributeCount(MeshAttribute::TextureCoordinates), 1);
-    CORRADE_COMPARE_AS(mesh->attribute<Vector2>(MeshAttribute::TextureCoordinates),
-        Containers::arrayView<Vector2>({
-            {0.5f, 1.0f}, {0.75f, 0.5f}, {0.5f, 0.9f}
-        }), TestSuite::Compare::Container);
 }
 
 void AssimpImporterTest::fileCallbackNotFound() {

diff --git a/src/MagnumPlugins/AssimpImporter/Test/mesh.dae b/src/MagnumPlugins/AssimpImporter/Test/mesh.dae
@@ -23,6 +23,16 @@
             </accessor>
           </technique_common>
         </source>
+        <source id="Cube-mesh-tangents">
+          <float_array id="Cube-mesh-tangents-array" count="3">1 0 0</float_array>
+          <technique_common>
+            <accessor source="#Cube-mesh-tangents-array" count="1" stride="3">
+              <param name="X" type="float"/>
+              <param name="Y" type="float"/>
+              <param name="Z" type="float"/>
+            </accessor>
+          </technique_common>
+        </source>
         <source id="Cube-mesh-map-0">
           <float_array id="Cube-mesh-map-0-array" count="6">0.5 1.0 0.75 0.5 0.5 0.9</float_array>
           <technique_common>
@@ -48,10 +58,13 @@
         <polylist count="1">
           <input semantic="VERTEX" source="#Cube-mesh-vertices" offset="0"/>
           <input semantic="NORMAL" source="#Cube-mesh-normals" offset="1"/>
-          <input semantic="TEXCOORD" source="#Cube-mesh-map-0" offset="2" set="0"/>
-          <input semantic="COLOR" source="#Cube-mesh-colors-Col" offset="3" set="0"/>
-          <vcount>3 </vcount>
-          <p>1 0 0 0 0 0 1 1 2 0 2 2</p>
+          <input semantic="TANGENT" source="#Cube-mesh-tangents" offset="2"/>
+          <input semantic="TEXCOORD" source="#Cube-mesh-map-0" offset="3" set="0"/>
+          <input semantic="COLOR" source="#Cube-mesh-colors-Col" offset="4" set="0"/>
+          <vcount>3</vcount>
+          <p>1 0 0 0 0
+             0 0 0 1 1
+             2 0 0 2 2</p>
         </polylist>
       </mesh>
     </geometry>