Fixed|Shadow Bias|BiasSurface: Latent bias lighting contributions whe…

…n surface loses all sources

When recalculating per-vertex bias lighting the special case of a
surface suddenly loosing all light contributions was not handled
correctly. This resulted in latent contributions from sources which
no longer affect the surface continuing to do so.

Todo: BiasSurface::Instance::evalLighting() should be revised as it
is now obvious that a previous refactoring effort to minimize the
effect of source lighting changes was not completed.

doomsday/client/src/render/biassurface.cpp

@@ -208,6 +208,17 @@ DENG2_PIMPL_NOREF(BiasSurface)
         if(vi.flags & VertexIllum::Unseen)
         {
             illumChanged = true;
+            for(int i = 0; i < MAX_AFFECTED; ++i)
+            {
+                BiasSource *source = vi.casted[i].source;
+                if(!source) continue;
+
+                // Remember the earliest time an affecting source changed.
+                if(latestSourceUpdate < source->lastUpdateTime())
+                {
+                    latestSourceUpdate = source->lastUpdateTime();
+                }
+            }
             vi.flags &= ~VertexIllum::Unseen;
         }
 
@@ -325,11 +336,13 @@ DENG2_PIMPL_NOREF(BiasSurface)
             newColor = newColor.min(saturated);
 
             // Is there a new destination?
-            if(!de::fequal(vi.dest.x, newColor.x, COLOR_CHANGE_THRESHOLD) ||
-               !de::fequal(vi.dest.y, newColor.y, COLOR_CHANGE_THRESHOLD) ||
-               !de::fequal(vi.dest.z, newColor.z, COLOR_CHANGE_THRESHOLD))
+            if(!affecting[0].source ||
+               (!de::fequal(vi.dest.x, newColor.x, COLOR_CHANGE_THRESHOLD) ||
+                !de::fequal(vi.dest.y, newColor.y, COLOR_CHANGE_THRESHOLD) ||
+                !de::fequal(vi.dest.z, newColor.z, COLOR_CHANGE_THRESHOLD)))
             {
-                if(vi.flags & VertexIllum::Interpolating)
+                if((vi.flags & VertexIllum::Interpolating) &&
+                   affecting[0].source)
                 {
                     // Must not lose the half-way interpolation.
                     Vector3f mid; vi.lerp(mid, biasTime);

doomsday/client/src/world/map.cpp

@@ -1183,21 +1183,26 @@ DENG2_OBSERVES(bsp::Partitioner, UnclosedSectorFound)
         // Check which sources have changed and update the tracker bits for
         // any affected surfaces.
         BiasTracker allChanges;
+        bool needUpdateSurfaces = false;
 
         for(int i = 0; i < bias.sources.count(); ++i)
         {
             BiasSource *bsrc = bias.sources.at(i);
 
             if(bsrc->trackChanges(allChanges, i, bias.currentTime))
             {
-                // Recalculate which sources affect which surfaces.
-                bias.lastChangeOnFrame = frameCount;
+                // We'll need to determine which source => surface affection.
+                needUpdateSurfaces = true;
             }
         }
 
+        if(!needUpdateSurfaces) return;
+
         /*
          * Apply changes to all surfaces:
          */
+        bias.lastChangeOnFrame = frameCount;
+
         foreach(Segment *seg, segments)
         {
             seg->updateBiasAffection(allChanges);