Fix interpolating to identity bone overrides (#16609)

The previous code immediately dropped identity overrides, even if there still was an interpolation to be done.
Also a little bit of cleanup, and setting an appropriate identity default for the scale property when interpolating.

For modders: As a workaround, you can add a tiny offset so that overrides aren't identity overrides.

games/devtest/mods/testentities/visuals.lua

@@ -95,7 +95,7 @@ core.register_entity("testentities:sam", {
 		self.object:set_bone_override("Head", {
 			scale = {
 				vec = vector.new(s, s, s),
-				absolute = true,
+				absolute = false,
 				interpolation = self._head_anim_duration,
 			},
 		})

src/activeobject.h

@@ -66,12 +66,12 @@ struct BoneOverride
 		v3f previous;
 		v3f vector;
 		bool absolute = false;
-		f32 interp_timer = 0;
+		f32 interp_duration = 0.0f;
 	} position;
 
 	v3f getPosition(v3f anim_pos) const {
-		f32 progress = dtime_passed / position.interp_timer;
-		if (progress > 1.0f || position.interp_timer == 0.0f)
+		f32 progress = dtime_passed / position.interp_duration;
+		if (progress > 1.0f || position.interp_duration == 0.0f)
 			progress = 1.0f;
 		return position.vector.getInterpolated(position.previous, progress)
 				+ (position.absolute ? v3f() : anim_pos);
@@ -85,14 +85,14 @@ struct BoneOverride
 		// so that we can return them in the appropriate getters
 		v3f next_radians;
 		bool absolute = false;
-		f32 interp_timer = 0;
+		f32 interp_duration = 0.0f;
 	} rotation;
 
 	v3f getRotationEulerDeg(v3f anim_rot_euler) const {
 		core::quaternion rot;
 
-		f32 progress = dtime_passed / rotation.interp_timer;
-		if (progress > 1.0f || rotation.interp_timer == 0.0f)
+		f32 progress = dtime_passed / rotation.interp_duration;
+		if (progress > 1.0f || rotation.interp_duration == 0.0f)
 			progress = 1.0f;
 		rot.slerp(rotation.previous, rotation.next, progress);
 		if (!rotation.absolute) {
@@ -107,27 +107,35 @@ struct BoneOverride
 
 	struct ScaleProperty
 	{
-		v3f previous;
-		v3f vector{1, 1, 1};
+		v3f previous = v3f(1.0f);
+		v3f vector = v3f(1.0f);
 		bool absolute = false;
-		f32 interp_timer = 0;
+		f32 interp_duration = 0.0f;
 	} scale;
 
 	v3f getScale(v3f anim_scale) const {
-		f32 progress = dtime_passed / scale.interp_timer;
-		if (progress > 1.0f || scale.interp_timer == 0.0f)
+		f32 progress = dtime_passed / scale.interp_duration;
+		if (progress > 1.0f || scale.interp_duration == 0.0f)
 			progress = 1.0f;
 		return scale.vector.getInterpolated(scale.previous, progress)
-				* (scale.absolute ? v3f(1) : anim_scale);
+				* (scale.absolute ? v3f(1.0f) : anim_scale);
 	}
 
-	f32 dtime_passed = 0;
+	f32 dtime_passed = 0.0f;
+
+	bool finishedInterpolation() const
+	{
+		return dtime_passed >= std::max(std::max(
+				position.interp_duration, rotation.interp_duration),
+				scale.interp_duration);
+	}
 
 	bool isIdentity() const
 	{
-		return !position.absolute && position.vector == v3f()
+		return finishedInterpolation()
+				&& !position.absolute && position.vector == v3f()
 				&& !rotation.absolute && rotation.next == core::quaternion()
-				&& !scale.absolute && scale.vector == v3f(1);
+				&& !scale.absolute && scale.vector == v3f(1.0f);
 	}
 };
 

src/client/content_cao.cpp

@@ -702,17 +702,21 @@ void GenericCAO::addToScene(ITextureSource *tsrc, scene::ISceneManager *smgr)
 			});
 
 			m_animated_meshnode->setOnAnimateCallback([&](f32 dtime) {
-				for (auto &it : m_bone_override) {
-					auto* bone = m_animated_meshnode->getJointNode(it.first.c_str());
-					if (!bone)
-						continue;
-
-					BoneOverride &props = it.second;
+				for (auto it = m_bone_override.begin(); it != m_bone_override.end();) {
+					BoneOverride &props = it->second;
 					props.dtime_passed += dtime;
 
-					bone->setPosition(props.getPosition(bone->getPosition()));
-					bone->setRotation(props.getRotationEulerDeg(bone->getRotation()));
-					bone->setScale(props.getScale(bone->getScale()));
+					if (props.isIdentity()) {
+						it = m_bone_override.erase(it);
+						continue;
+					}
+
+					if (auto *bone = m_animated_meshnode->getJointNode(it->first.c_str())) {
+						bone->setPosition(props.getPosition(bone->getPosition()));
+						bone->setRotation(props.getRotationEulerDeg(bone->getRotation()));
+						bone->setScale(props.getScale(bone->getScale()));
+					}
+					++it;
 				}
 			});
 		} else
@@ -1689,9 +1693,9 @@ void GenericCAO::processMessage(const std::string &data)
 			props.scale.previous = props.scale.vector;
 		} else {
 			// Disable interpolation
-			props.position.interp_timer = 0.0f;
-			props.rotation.interp_timer = 0.0f;
-			props.scale.interp_timer = 0.0f;
+			props.position.interp_duration = 0.0f;
+			props.rotation.interp_duration = 0.0f;
+			props.scale.interp_duration = 0.0f;
 		}
 		// Read new values
 		props.position.vector = readV3F32(is);
@@ -1703,19 +1707,15 @@ void GenericCAO::processMessage(const std::string &data)
 			props.position.absolute = true;
 			props.rotation.absolute = true;
 		} else {
-			props.position.interp_timer = readF32(is);
-			props.rotation.interp_timer = readF32(is);
-			props.scale.interp_timer = readF32(is);
+			props.position.interp_duration = readF32(is);
+			props.rotation.interp_duration = readF32(is);
+			props.scale.interp_duration = readF32(is);
 			u8 absoluteFlag = readU8(is);
 			props.position.absolute = (absoluteFlag & 1) > 0;
 			props.rotation.absolute = (absoluteFlag & 2) > 0;
 			props.scale.absolute = (absoluteFlag & 4) > 0;
 		}
-		if (props.isIdentity()) {
-			m_bone_override.erase(bone);
-		} else {
-			m_bone_override[bone] = props;
-		}
+		m_bone_override[bone] = props;
 	} else if (cmd == AO_CMD_ATTACH_TO) {
 		u16 parent_id = readS16(is);
 		std::string bone = deSerializeString16(is);

src/script/lua_api/l_object.cpp

@@ -668,7 +668,7 @@ int ObjectRef::l_set_bone_override(lua_State *L)
 
 		lua_getfield(L, -1, "interpolation");
 		if (lua_isnumber(L, -1))
-			prop.interp_timer = lua_tonumber(L, -1);
+			prop.interp_duration = lua_tonumber(L, -1);
 		lua_pop(L, 1);
 	};
 
@@ -718,7 +718,7 @@ static void push_bone_override(lua_State *L, const BoneOverride &props)
 		lua_newtable(L);
 		push_v3f(L, vec);
 		lua_setfield(L, -2, "vec");
-		lua_pushnumber(L, prop.interp_timer);
+		lua_pushnumber(L, prop.interp_duration);
 		lua_setfield(L, -2, "interpolation");
 		lua_pushboolean(L, prop.absolute);
 		lua_setfield(L, -2, "absolute");

src/server/unit_sao.cpp

@@ -312,9 +312,9 @@ std::string UnitSAO::generateUpdateBoneOverrideCommand(
 	props.rotation.next.toEuler(euler_rot);
 	writeV3F32(os, euler_rot * core::RADTODEG);
 	writeV3F32(os, props.scale.vector);
-	writeF32(os, props.position.interp_timer);
-	writeF32(os, props.rotation.interp_timer);
-	writeF32(os, props.scale.interp_timer);
+	writeF32(os, props.position.interp_duration);
+	writeF32(os, props.rotation.interp_duration);
+	writeF32(os, props.scale.interp_duration);
 	writeU8(os, (props.position.absolute & 1) << 0
 	          | (props.rotation.absolute & 1) << 1
 	          | (props.scale.absolute & 1) << 2);