Auto LOD fixes and improvements

* Fixed LODs for shadow meshes.
* Added a merging step before simplification. This helps with tesselated
  meshes that were previously left untouched. The angle difference at
  wich edges ar considered "hard" can be tweaked as an import setting.
* LODs will now start with the highest decimation possible and keep
  doubling (approximately) the number of triangles from there. This
  makes sure that very low triangle counts are included when possible.
* Given more weight to normal preservation.
* Modified MeshOptimizer to report distance-based error instead of
  including attributes in the reported metrics.
* Added attribute transference between the original mesh and the
  various LODs. Right now only normals are taken into account,
  but it could be expanded to other attributes in the future.

5 files changed, 209 insertions, 8 deletions

diff --git a/modules/raycast/lightmap_raycaster.cpp b/modules/raycast/lightmap_raycaster.cpp
index 0583acc119..fdcf509da8 100644
--- a/modules/raycast/lightmap_raycaster.cpp
+++ b/modules/raycast/lightmap_raycaster.cpp
@@ -168,7 +168,7 @@ void LightmapRaycasterEmbree::clear_mesh_filter() {
 	filter_meshes.clear();
 }
 
-void embree_error_handler(void *p_user_data, RTCError p_code, const char *p_str) {
+void embree_lm_error_handler(void *p_user_data, RTCError p_code, const char *p_str) {
 	print_error("Embree error: " + String(p_str));
 }
 
@@ -179,16 +179,11 @@ LightmapRaycasterEmbree::LightmapRaycasterEmbree() {
 #endif
 
 	embree_device = rtcNewDevice(nullptr);
-	rtcSetDeviceErrorFunction(embree_device, &embree_error_handler, nullptr);
+	rtcSetDeviceErrorFunction(embree_device, &embree_lm_error_handler, nullptr);
 	embree_scene = rtcNewScene(embree_device);
 }
 
 LightmapRaycasterEmbree::~LightmapRaycasterEmbree() {
-#ifdef __SSE2__
-	_MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_OFF);
-	_MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_OFF);
-#endif
-
 	if (embree_scene != nullptr) {
 		rtcReleaseScene(embree_scene);
 	}
diff --git a/modules/raycast/lightmap_raycaster.h b/modules/raycast/lightmap_raycaster.h
index 4c3de27837..290b0a1cf3 100644
--- a/modules/raycast/lightmap_raycaster.h
+++ b/modules/raycast/lightmap_raycaster.h
@@ -30,9 +30,9 @@
 
 #ifdef TOOLS_ENABLED
 
+#include "core/io/image.h"
 #include "core/object/object.h"
 #include "scene/3d/lightmapper.h"
-#include "scene/resources/mesh.h"
 
 #include <embree3/rtcore.h>
 
diff --git a/modules/raycast/register_types.cpp b/modules/raycast/register_types.cpp
index 78ca91309f..ed99e635e1 100644
--- a/modules/raycast/register_types.cpp
+++ b/modules/raycast/register_types.cpp
@@ -32,12 +32,14 @@
 
 #include "lightmap_raycaster.h"
 #include "raycast_occlusion_cull.h"
+#include "static_raycaster.h"
 
 RaycastOcclusionCull *raycast_occlusion_cull = nullptr;
 
 void register_raycast_types() {
 #ifdef TOOLS_ENABLED
 	LightmapRaycasterEmbree::make_default_raycaster();
+	StaticRaycasterEmbree::make_default_raycaster();
 #endif
 	raycast_occlusion_cull = memnew(RaycastOcclusionCull);
 }
@@ -46,4 +48,7 @@ void unregister_raycast_types() {
 	if (raycast_occlusion_cull) {
 		memdelete(raycast_occlusion_cull);
 	}
+#ifdef TOOLS_ENABLED
+	StaticRaycasterEmbree::free();
+#endif
 }
diff --git a/modules/raycast/static_raycaster.cpp b/modules/raycast/static_raycaster.cpp
new file mode 100644
index 0000000000..2ba65eebf8
--- /dev/null
+++ b/modules/raycast/static_raycaster.cpp
@@ -0,0 +1,137 @@
+/*************************************************************************/
+/*  static_raycaster.cpp                                                 */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* 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.                */
+/*************************************************************************/
+
+#ifdef TOOLS_ENABLED
+
+#include "static_raycaster.h"
+
+#ifdef __SSE2__
+#include <pmmintrin.h>
+#endif
+
+RTCDevice StaticRaycasterEmbree::embree_device;
+
+StaticRaycaster *StaticRaycasterEmbree::create_embree_raycaster() {
+	return memnew(StaticRaycasterEmbree);
+}
+
+void StaticRaycasterEmbree::make_default_raycaster() {
+	create_function = create_embree_raycaster;
+}
+
+void StaticRaycasterEmbree::free() {
+	if (embree_device) {
+		rtcReleaseDevice(embree_device);
+	}
+}
+
+bool StaticRaycasterEmbree::intersect(Ray &r_ray) {
+	RTCIntersectContext context;
+	rtcInitIntersectContext(&context);
+	rtcIntersect1(embree_scene, &context, (RTCRayHit *)&r_ray);
+	return r_ray.geomID != RTC_INVALID_GEOMETRY_ID;
+}
+
+void StaticRaycasterEmbree::intersect(Vector<Ray> &r_rays) {
+	Ray *rays = r_rays.ptrw();
+	for (int i = 0; i < r_rays.size(); ++i) {
+		intersect(rays[i]);
+	}
+}
+
+void StaticRaycasterEmbree::add_mesh(const PackedVector3Array &p_vertices, const PackedInt32Array &p_indices, unsigned int p_id) {
+	RTCGeometry embree_mesh = rtcNewGeometry(embree_device, RTC_GEOMETRY_TYPE_TRIANGLE);
+
+	int vertex_count = p_vertices.size();
+
+	Vector3 *embree_vertices = (Vector3 *)rtcSetNewGeometryBuffer(embree_mesh, RTC_BUFFER_TYPE_VERTEX, 0, RTC_FORMAT_FLOAT3, sizeof(Vector3), vertex_count);
+	memcpy(embree_vertices, p_vertices.ptr(), sizeof(Vector3) * vertex_count);
+
+	if (p_indices.is_empty()) {
+		ERR_FAIL_COND(vertex_count % 3 != 0);
+		uint32_t *embree_triangles = (uint32_t *)rtcSetNewGeometryBuffer(embree_mesh, RTC_BUFFER_TYPE_INDEX, 0, RTC_FORMAT_UINT3, sizeof(uint32_t) * 3, vertex_count / 3);
+		for (int i = 0; i < vertex_count; i++) {
+			embree_triangles[i] = i;
+		}
+	} else {
+		uint32_t *embree_triangles = (uint32_t *)rtcSetNewGeometryBuffer(embree_mesh, RTC_BUFFER_TYPE_INDEX, 0, RTC_FORMAT_UINT3, sizeof(uint32_t) * 3, p_indices.size() / 3);
+		memcpy(embree_triangles, p_indices.ptr(), sizeof(uint32_t) * p_indices.size());
+	}
+
+	rtcCommitGeometry(embree_mesh);
+	rtcAttachGeometryByID(embree_scene, embree_mesh, p_id);
+	rtcReleaseGeometry(embree_mesh);
+}
+
+void StaticRaycasterEmbree::commit() {
+	rtcCommitScene(embree_scene);
+}
+
+void StaticRaycasterEmbree::set_mesh_filter(const Set<int> &p_mesh_ids) {
+	for (Set<int>::Element *E = p_mesh_ids.front(); E; E = E->next()) {
+		rtcDisableGeometry(rtcGetGeometry(embree_scene, E->get()));
+	}
+	rtcCommitScene(embree_scene);
+	filter_meshes = p_mesh_ids;
+}
+
+void StaticRaycasterEmbree::clear_mesh_filter() {
+	for (Set<int>::Element *E = filter_meshes.front(); E; E = E->next()) {
+		rtcEnableGeometry(rtcGetGeometry(embree_scene, E->get()));
+	}
+	rtcCommitScene(embree_scene);
+	filter_meshes.clear();
+}
+
+void embree_error_handler(void *p_user_data, RTCError p_code, const char *p_str) {
+	print_error("Embree error: " + String(p_str));
+}
+
+StaticRaycasterEmbree::StaticRaycasterEmbree() {
+#ifdef __SSE2__
+	_MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
+	_MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
+#endif
+
+	if (!embree_device) {
+		embree_device = rtcNewDevice(nullptr);
+		rtcSetDeviceErrorFunction(embree_device, &embree_error_handler, nullptr);
+	}
+
+	embree_scene = rtcNewScene(embree_device);
+}
+
+StaticRaycasterEmbree::~StaticRaycasterEmbree() {
+	if (embree_scene != nullptr) {
+		rtcReleaseScene(embree_scene);
+	}
+}
+
+#endif
diff --git a/modules/raycast/static_raycaster.h b/modules/raycast/static_raycaster.h
new file mode 100644
index 0000000000..6b13ecf690
--- /dev/null
+++ b/modules/raycast/static_raycaster.h
@@ -0,0 +1,64 @@
+/*************************************************************************/
+/*  static_raycaster.h                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* 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.                */
+/*************************************************************************/
+
+#ifdef TOOLS_ENABLED
+
+#include "core/math/static_raycaster.h"
+
+#include <embree3/rtcore.h>
+
+class StaticRaycasterEmbree : public StaticRaycaster {
+	GDCLASS(StaticRaycasterEmbree, StaticRaycaster);
+
+private:
+	static RTCDevice embree_device;
+	RTCScene embree_scene;
+
+	Set<int> filter_meshes;
+
+public:
+	virtual bool intersect(Ray &p_ray) override;
+	virtual void intersect(Vector<Ray> &r_rays) override;
+
+	virtual void add_mesh(const PackedVector3Array &p_vertices, const PackedInt32Array &p_indices, unsigned int p_id) override;
+	virtual void commit() override;
+
+	virtual void set_mesh_filter(const Set<int> &p_mesh_ids) override;
+	virtual void clear_mesh_filter() override;
+
+	static StaticRaycaster *create_embree_raycaster();
+	static void make_default_raycaster();
+	static void free();
+
+	StaticRaycasterEmbree();
+	~StaticRaycasterEmbree();
+};
+
+#endif