Fix the Use Nearest Mipmap Filter project setting not working

The project setting wasn't being used anywhere.

This also tweaks the property hints to denote that these properties
are only effective after a restart.

doc/classes/ProjectSettings.xml

@@ -1713,9 +1713,11 @@
 		</member>
 		<member name="rendering/textures/default_filters/anisotropic_filtering_level" type="int" setter="" getter="" default="2">
 			Sets the maximum number of samples to take when using anisotropic filtering on textures (as a power of two). A higher sample count will result in sharper textures at oblique angles, but is more expensive to compute. A value of [code]0[/code] forcibly disables anisotropic filtering, even on materials where it is enabled.
+			[b]Note:[/b] This property is only read when the project starts. There is currently no way to change this setting at run-time.
 		</member>
 		<member name="rendering/textures/default_filters/use_nearest_mipmap_filter" type="bool" setter="" getter="" default="false">
 			If [code]true[/code], uses nearest-neighbor mipmap filtering when using mipmaps (also called "bilinear filtering"), which will result in visible seams appearing between mipmap stages. This may increase performance in mobile as less memory bandwidth is used. If [code]false[/code], linear mipmap filtering (also called "trilinear filtering") is used.
+			[b]Note:[/b] This property is only read when the project starts. There is currently no way to change this setting at run-time.
 		</member>
 		<member name="rendering/textures/light_projectors/filter" type="int" setter="" getter="" default="3">
 		</member>

servers/rendering/renderer_rd/renderer_storage_rd.cpp

@@ -9129,25 +9129,41 @@ RendererStorageRD::RendererStorageRD() {
 				case RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST_WITH_MIPMAPS: {
 					sampler_state.mag_filter = RD::SAMPLER_FILTER_NEAREST;
 					sampler_state.min_filter = RD::SAMPLER_FILTER_LINEAR;
-					sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					if (GLOBAL_GET("rendering/textures/default_filters/use_nearest_mipmap_filter")) {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_NEAREST;
+					} else {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					}
 				} break;
 				case RS::CANVAS_ITEM_TEXTURE_FILTER_LINEAR_WITH_MIPMAPS: {
 					sampler_state.mag_filter = RD::SAMPLER_FILTER_LINEAR;
 					sampler_state.min_filter = RD::SAMPLER_FILTER_LINEAR;
-					sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					if (GLOBAL_GET("rendering/textures/default_filters/use_nearest_mipmap_filter")) {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_NEAREST;
+					} else {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					}
 
 				} break;
 				case RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST_WITH_MIPMAPS_ANISOTROPIC: {
 					sampler_state.mag_filter = RD::SAMPLER_FILTER_NEAREST;
 					sampler_state.min_filter = RD::SAMPLER_FILTER_LINEAR;
-					sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					if (GLOBAL_GET("rendering/textures/default_filters/use_nearest_mipmap_filter")) {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_NEAREST;
+					} else {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					}
 					sampler_state.use_anisotropy = true;
 					sampler_state.anisotropy_max = 1 << int(GLOBAL_GET("rendering/textures/default_filters/anisotropic_filtering_level"));
 				} break;
 				case RS::CANVAS_ITEM_TEXTURE_FILTER_LINEAR_WITH_MIPMAPS_ANISOTROPIC: {
 					sampler_state.mag_filter = RD::SAMPLER_FILTER_LINEAR;
 					sampler_state.min_filter = RD::SAMPLER_FILTER_LINEAR;
-					sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					if (GLOBAL_GET("rendering/textures/default_filters/use_nearest_mipmap_filter")) {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_NEAREST;
+					} else {
+						sampler_state.mip_filter = RD::SAMPLER_FILTER_LINEAR;
+					}
 					sampler_state.use_anisotropy = true;
 					sampler_state.anisotropy_max = 1 << int(GLOBAL_GET("rendering/textures/default_filters/anisotropic_filtering_level"));
 

servers/rendering_server.cpp

@@ -2826,8 +2826,8 @@ RenderingServer::RenderingServer() {
 	GLOBAL_DEF("rendering/driver/depth_prepass/enable", true);
 	GLOBAL_DEF("rendering/driver/depth_prepass/disable_for_vendors", "PowerVR,Mali,Adreno,Apple");
 
-	GLOBAL_DEF("rendering/textures/default_filters/use_nearest_mipmap_filter", false);
-	GLOBAL_DEF("rendering/textures/default_filters/anisotropic_filtering_level", 2);
+	GLOBAL_DEF_RST("rendering/textures/default_filters/use_nearest_mipmap_filter", false);
+	GLOBAL_DEF_RST("rendering/textures/default_filters/anisotropic_filtering_level", 2);
 	ProjectSettings::get_singleton()->set_custom_property_info("rendering/textures/default_filters/anisotropic_filtering_level", PropertyInfo(Variant::INT, "rendering/textures/default_filters/anisotropic_filtering_level", PROPERTY_HINT_ENUM, "Disabled (Fastest),2x (Faster),4x (Fast),8x (Average),16x (Slow)"));
 
 	GLOBAL_DEF("rendering/camera/depth_of_field/depth_of_field_bokeh_shape", 1);