Fixed various issues in the conversion from lumobj to vlight for the …

…purposes of sprite and model lighting.

TODO: The debug display I added to draw the light vectors affecting a given sprite indicate that there are a few remaining problems further up chain, mostly to do with vertical offsets (affecting light vectors don't point in the direction of the origin).

doomsday/engine/portable/src/r_things.c

@@ -1464,10 +1464,10 @@ boolean visSpriteLightIterator(const lumobj_t* lum, float xyDist, void* data)
 
                 // Calculate the normalized direction vector, pointing out of
                 // the light origin.
-                vlight->vector[VX] = (params->pos[VX] - lum->pos[VX]) / dist;
-                vlight->vector[VY] = (params->pos[VY] - lum->pos[VY]) / dist;
-                vlight->vector[VZ] = (params->pos[VZ] - lum->pos[VZ] +
-                                        LUM_OMNI(lum)->zOff) / dist;
+                vlight->vector[VX] = (lum->pos[VX] - params->pos[VX]) / dist;
+                vlight->vector[VY] = (lum->pos[VY] - params->pos[VY]) / dist;
+                vlight->vector[VZ] = (lum->pos[VZ] + LUM_OMNI(lum)->zOff -
+                                        params->pos[VZ]) / dist;
 
                 vlight->color[CR] = LUM_OMNI(lum)->color[CR] * intensity;
                 vlight->color[CG] = LUM_OMNI(lum)->color[CG] * intensity;
@@ -1489,7 +1489,7 @@ boolean visSpriteLightIterator(const lumobj_t* lum, float xyDist, void* data)
                  */
                 vlight->vector[VX] = LUM_PLANE(lum)->normal[VX];
                 vlight->vector[VY] = LUM_PLANE(lum)->normal[VY];
-                vlight->vector[VZ] = LUM_PLANE(lum)->normal[VZ];
+                vlight->vector[VZ] = -LUM_PLANE(lum)->normal[VZ];
 
                 vlight->color[CR] = LUM_PLANE(lum)->color[CR] * intensity;
                 vlight->color[CG] = LUM_PLANE(lum)->color[CG] * intensity;
@@ -1571,7 +1571,7 @@ uint R_CollectAffectingLights(const collectaffectinglights_params_t* params)
                                  &vars, visSpriteLightIterator);
     }
 
-    return vLightListIdx;
+    return vLightListIdx + 1;
 }
 
 /**

doomsday/engine/portable/src/rend_sprite.c

@@ -855,6 +855,26 @@ void Rend_DrawMasked(void)
     }
 }
 
+#if _DEBUG
+boolean drawVLightVector(const vlight_t* light, void* context)
+{
+    float               scale = 100;
+
+    DGL_Begin(DGL_LINES);
+    {
+        DGL_Color4f(light->color[CR], light->color[CG], light->color[CB], 1);
+        DGL_Vertex3f(scale * light->vector[VX],
+                     scale * light->vector[VZ],
+                     scale * light->vector[VY]);
+        DGL_Color4f(0, 0, 0, 1);
+        DGL_Vertex3f(0, 0, 0);
+    }
+    DGL_End();
+
+    return true; // Continue iteration.
+}
+#endif
+
 void Rend_RenderSprite(const rendspriteparams_t* params)
 {
     int                 i;
@@ -936,6 +956,30 @@ DGL_Enable(DGL_TEXTURING);
                          spriteLight + 1, params->ambientColor);
     }
 
+/*#if _DEBUG
+    if(params->vLightListIdx)
+    {   // Draw the vlight vectors, for debug.
+        DGL_Disable(DGL_TEXTURING);
+        glDisable(GL_DEPTH_TEST);
+        glDisable(GL_CULL_FACE);
+
+        DGL_MatrixMode(DGL_MODELVIEW);
+        DGL_PushMatrix();
+
+        DGL_Translatef(params->center[VX], params->center[VZ],
+                       params->center[VY]);
+
+        VL_ListIterator(params->vLightListIdx, NULL, drawVLightVector);
+
+        DGL_MatrixMode(DGL_MODELVIEW);
+        DGL_PopMatrix();
+
+        glEnable(GL_CULL_FACE);
+        glEnable(GL_DEPTH_TEST);
+        DGL_Enable(DGL_TEXTURING);
+    }
+#endif*/
+
     // Do we need to do some aligning?
     if(params->viewAligned || alwaysAlign >= 2)
     {