resource: add has_{tangents,bitangents}()

src/resource/mesh.cpp

@@ -82,6 +82,16 @@ namespace mesh
 		return array::size(g._uvs) != 0;
 	}
 
+	bool has_tangents(Geometry &g)
+	{
+		return array::size(g._tangents) != 0;
+	}
+
+	bool has_bitangents(Geometry &g)
+	{
+		return array::size(g._bitangents) != 0;
+	}
+
 	static u32 vertex_stride(Geometry &g)
 	{
 		u32 stride = 0;

src/resource/mesh.h

@@ -67,6 +67,12 @@ namespace mesh
 	///
 	bool has_uvs(Geometry &g);
 
+	///
+	bool has_tangents(Geometry &g);
+
+	///
+	bool has_bitangents(Geometry &g);
+
 	///
 	s32 parse(Mesh &m, CompileOptions &opts, const char *path);