Fix backward lamp distance calculation

When use_sphere is enabled, the lamp cutoff is at exactly the distance
value. Otherwise, the distance value is the point at which the lamp
intensity is half its starting value.

This probably doesn't match Blender 1-to-1, but it's closer to Blender's
lighting logic than the existing use_sphere calculations.

korman/exporter/animation.py

@@ -162,7 +162,7 @@ class AnimationConverter:
         if distance_fcurve is not None:
             channel = plScalarControllerChannel()
             channel.controller = self.make_scalar_leaf_controller(distance_fcurve,
-                                                                  lambda x: x * 2 if lamp.use_sphere else x)
+                                                                  lambda x: x if lamp.use_sphere else x * 2)
             applicator = plOmniCutoffApplicator()
             applicator.channelName = name
             applicator.channel = channel
@@ -175,7 +175,7 @@ class AnimationConverter:
         elif falloff == "INVERSE_LINEAR":
             def convert_linear_atten(distance, energy):
                 intens = abs(energy[0])
-                atten_end = distance[0] * 2 if lamp.use_sphere else distance[0]
+                atten_end = distance[0] if lamp.use_sphere else distance[0] * 2
                 return light_converter.convert_attenuation_linear(intens, atten_end)
 
             keyframes = self._process_fcurves([distance_fcurve, energy_fcurve], convert_linear_atten,
@@ -190,7 +190,7 @@ class AnimationConverter:
         elif falloff == "INVERSE_SQUARE":
             def convert_quadratic_atten(distance, energy):
                 intens = abs(energy[0])
-                atten_end = distance[0] * 2 if lamp.use_sphere else distance[0]
+                atten_end = distance[0] if lamp.use_sphere else distance[0] * 2
                 return light_converter.convert_attenuation_quadratic(intens, atten_end)
 
             keyframes = self._process_fcurves([distance_fcurve, energy_fcurve], convert_quadratic_atten,

korman/exporter/rtlight.py

@@ -65,7 +65,7 @@ class LightConverter:
 
     def convert_attenuation(self, lamp):
         intens = abs(lamp.energy)
-        attenEnd = lamp.distance * 2 if lamp.use_sphere else lamp.distance
+        attenEnd = lamp.distance if lamp.use_sphere else lamp.distance * 2
         return (intens, attenEnd)
 
     def convert_attenuation_linear(self, intensity, end):