BGE: New hysteresis offset to improve LOD level transitions

This change introduces a new hysteresis parameter that it will be added
or subtracted to/from the LOD distance to avoid popping when a LOD
object moves close to the LOD transition continuously.

Then, we have the following:

- a new LOD Hysteresis setting per scene (default 10%) which is located
in Scene context --> Level of Detail panel. This scene parameter also
will active/deactive the scene hysteresis.
- and a new LOD Hysteresis setting per object (default 10%) which is
located in Object context --> Levels of Detail panel. The LOD hysteresis
setting per object (if active) will overwrite the hysteresis setting per
scene value.

For the new blends: the hysteresis setting per scene would be active by
default and the per object would be inactive by default.
For the old blends: both hysteresis settings (per scene and per object)
would be inactive by default. A quick way to take advantage of this
feature for old blends would be to activate the hysteresis parameter in
the scene context -> Level of Detail panel

Reviewers: campbellbarton, kupoman, moguri

Reviewed By: kupoman, moguri

Subscribers: nonamejuju, lordodin

Differential Revision: https://developer.blender.org/D957

1 files changed, 4 insertions, 0 deletions

diff --git a/source/gameengine/Converter/BL_BlenderDataConversion.cpp b/source/gameengine/Converter/BL_BlenderDataConversion.cpp
index cd2e2151034..7b5cc457ee6 100644
--- a/source/gameengine/Converter/BL_BlenderDataConversion.cpp
+++ b/source/gameengine/Converter/BL_BlenderDataConversion.cpp
@@ -1554,6 +1554,10 @@ static KX_GameObject *gameobject_from_blenderobject(
 				}
 				gameobj->AddLodMesh(BL_ConvertMesh(lodmesh, lodmatob, kxscene, converter, libloading));
 			}
+			if (blenderscene->gm.lodflag & SCE_LOD_USE_HYST) {
+				kxscene->SetLodHysteresis(true);
+				gameobj->SetLodHysteresisValue(blenderscene->gm.scehysteresis);
+			}
 		}
 	
 		// for all objects: check whether they want to