1 files changed, 20 insertions, 3 deletions

diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index ecfb035b82..90280e0372 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -2797,9 +2797,26 @@ Error GLTFDocument::_parse_meshes(Ref<GLTFState> p_state) {
 				array[Mesh::ARRAY_INDEX] = indices;
 			}
 
-			bool generate_tangents = p_state->force_generate_tangents && (primitive == Mesh::PRIMITIVE_TRIANGLES && !a.has("TANGENT") && a.has("TEXCOORD_0") && a.has("NORMAL"));
+			bool generate_tangents = p_state->force_generate_tangents && (primitive == Mesh::PRIMITIVE_TRIANGLES && !a.has("TANGENT") && a.has("NORMAL"));
+
+			if (generate_tangents && !a.has("TEXCOORD_0")) {
+				// If we don't have UVs we provide a dummy tangent array.
+				Vector<float> tangents;
+				tangents.resize(vertex_num * 4);
+				float *tangentsw = tangents.ptrw();
+
+				Vector<Vector3> normals = array[Mesh::ARRAY_NORMAL];
+				for (int k = 0; k < vertex_num; k++) {
+					Vector3 tan = Vector3(0.0, 1.0, 0.0).cross(normals[k]);
+					tangentsw[k * 4 + 0] = tan.x;
+					tangentsw[k * 4 + 1] = tan.y;
+					tangentsw[k * 4 + 2] = tan.z;
+					tangentsw[k * 4 + 3] = 1.0;
+				}
+				array[Mesh::ARRAY_TANGENT] = tangents;
+			}
 
-			if (p_state->force_disable_compression || !a.has("POSITION") || !a.has("NORMAL") || !(a.has("TANGENT") || generate_tangents) || p.has("targets") || (a.has("JOINTS_0") || a.has("JOINTS_1"))) {
+			if (p_state->force_disable_compression || !a.has("POSITION") || !a.has("NORMAL") || p.has("targets") || (a.has("JOINTS_0") || a.has("JOINTS_1"))) {
 				flags &= ~RS::ARRAY_FLAG_COMPRESS_ATTRIBUTES;
 			}
 
@@ -2810,7 +2827,7 @@ Error GLTFDocument::_parse_meshes(Ref<GLTFState> p_state) {
 				mesh_surface_tool->set_skin_weight_count(SurfaceTool::SKIN_8_WEIGHTS);
 			}
 			mesh_surface_tool->index();
-			if (generate_tangents) {
+			if (generate_tangents && a.has("TEXCOORD_0")) {
 				//must generate mikktspace tangents.. ergh..
 				mesh_surface_tool->generate_tangents();
 			}