From 5d9f5c54ef567770ecdd65cb33503281c9c9f477 Mon Sep 17 00:00:00 2001
From: Manuel Maceira <manuelmaceira.m@gmail.com>
Date: Fri, 12 Dec 2025 16:34:36 -0300
Subject: [PATCH] GLTF: Fix emissive texture import when emissiveFactor is
 absent

---
 modules/gltf/gltf_document.cpp                |   6 +-
 .../emissive_no_factor.gltf                   |  36 ++++++++++
 .../data/gltf_emissive_no_factor/texture.png  | Bin 0 -> 92 bytes
 modules/gltf/tests/test_gltf_emissive.h       |  68 ++++++++++++++++++
 4 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 modules/gltf/tests/data/gltf_emissive_no_factor/emissive_no_factor.gltf
 create mode 100644 modules/gltf/tests/data/gltf_emissive_no_factor/texture.png
 create mode 100644 modules/gltf/tests/test_gltf_emissive.h

diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index 6a675fe279f..71d4163d210 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -3105,7 +3105,11 @@ Error GLTFDocument::_parse_materials(Ref<GLTFState> p_state) {
 			if (bct.has("index")) {
 				material->set_texture(BaseMaterial3D::TEXTURE_EMISSION, _get_texture(p_state, bct["index"], TEXTURE_TYPE_GENERIC));
 				material->set_feature(BaseMaterial3D::FEATURE_EMISSION, true);
-				material->set_emission(Color(0, 0, 0));
+				material->set_emission_operator(BaseMaterial3D::EMISSION_OP_MULTIPLY);
+				// glTF spec: emissiveFactor × emissiveTexture. Use WHITE if no factor specified.
+				if (!material_dict.has("emissiveFactor")) {
+					material->set_emission(Color(1, 1, 1));
+				}
 			}
 		}
 
diff --git a/modules/gltf/tests/data/gltf_emissive_no_factor/emissive_no_factor.gltf b/modules/gltf/tests/data/gltf_emissive_no_factor/emissive_no_factor.gltf
new file mode 100644
index 00000000000..deef16c2b82
--- /dev/null
+++ b/modules/gltf/tests/data/gltf_emissive_no_factor/emissive_no_factor.gltf
@@ -0,0 +1,36 @@
+{
+  "asset": { "version": "2.0", "generator": "Test for emissiveTexture without emissiveFactor" },
+  "scene": 0,
+  "scenes": [{ "name": "Scene", "nodes": [0] }],
+  "nodes": [{ "name": "Cube", "mesh": 0 }],
+  "meshes": [{
+    "name": "Cube",
+    "primitives": [{
+      "attributes": { "POSITION": 0 },
+      "material": 0
+    }]
+  }],
+  "materials": [{
+    "name": "EmissiveNoFactor",
+    "emissiveTexture": { "index": 0 },
+    "pbrMetallicRoughness": {}
+  }],
+  "textures": [{ "source": 0 }],
+  "images": [{ "uri": "texture.png" }],
+  "accessors": [{
+    "bufferView": 0,
+    "componentType": 5126,
+    "count": 3,
+    "type": "VEC3",
+    "max": [1, 1, 0],
+    "min": [-1, -1, 0]
+  }],
+  "bufferViews": [{
+    "buffer": 0,
+    "byteLength": 36
+  }],
+  "buffers": [{
+    "uri": "data:application/octet-stream;base64,AAAAAAAAgL8AAAAAAAAAAAAAAAAAAIA/AACAvwAAgD8AAAAA",
+    "byteLength": 36
+  }]
+}
diff --git a/modules/gltf/tests/data/gltf_emissive_no_factor/texture.png b/modules/gltf/tests/data/gltf_emissive_no_factor/texture.png
new file mode 100644
index 0000000000000000000000000000000000000000..cb872e7419b7904df8cc02fa9fb7f84a8885bb0a
GIT binary patch
literal 92
zcmeAS@N?(olHy`uVBq!ia0vp^Od!m`1|*BN@u~nR#^NA%Cx&(BWL^R}VxBIJAsjQ4
nQxXz>{GZ?0*vRT+Xu!arp}@j4(|hkJpb7?0S3j3^P6<r_NyioC

literal 0
HcmV?d00001

diff --git a/modules/gltf/tests/test_gltf_emissive.h b/modules/gltf/tests/test_gltf_emissive.h
new file mode 100644
index 00000000000..e5652df4574
--- /dev/null
+++ b/modules/gltf/tests/test_gltf_emissive.h
@@ -0,0 +1,68 @@
+/**************************************************************************/
+/*  test_gltf_emissive.h                                                  */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "test_gltf.h"
+
+#ifdef TOOLS_ENABLED
+
+namespace TestGltf {
+
+TEST_CASE("[SceneTree][Node] GLTF emissiveTexture without emissiveFactor uses white emission") {
+	init("gltf_emissive_no_factor", "res://");
+
+	Node *loaded = gltf_import("res://emissive_no_factor.gltf");
+	CHECK_MESSAGE(loaded != nullptr, "Failed to load GLB.");
+
+	MeshInstance3D *mesh = Object::cast_to<MeshInstance3D>(loaded->find_child("Cube", true, true));
+	CHECK_MESSAGE(mesh != nullptr, "Mesh not found.");
+
+	Ref<StandardMaterial3D> mat = mesh->get_active_material(0);
+	CHECK_MESSAGE(mat.is_valid(), "Material not found.");
+
+	// Emission should be enabled.
+	CHECK(mat->get_feature(BaseMaterial3D::FEATURE_EMISSION));
+
+	// Emission operator should be MULTIPLY per glTF spec.
+	CHECK(mat->get_emission_operator() == BaseMaterial3D::EMISSION_OP_MULTIPLY);
+
+	// Without emissiveFactor, emission color should be WHITE, not BLACK.
+	Color c = mat->get_emission();
+	CHECK_MESSAGE(c.r > 0.9f, "Emission red should be ~1.0 when emissiveFactor is absent.");
+	CHECK_MESSAGE(c.g > 0.9f, "Emission green should be ~1.0 when emissiveFactor is absent.");
+	CHECK_MESSAGE(c.b > 0.9f, "Emission blue should be ~1.0 when emissiveFactor is absent.");
+
+	memdelete(loaded);
+}
+
+} // namespace TestGltf
+
+#endif // TOOLS_ENABLED