CalcSurfaceExtents: more info in extents error message

rehlds/engine/model.cpp

@@ -854,6 +854,7 @@ void CalcSurfaceExtents(msurface_t *s)
 	int		i, j, e;
 	mvertex_t	*v;
 	mtexinfo_t	*tex;
+	vec3_t		middle{};
 	int		bmins[2], bmaxs[2];
 
 	mins[0] = mins[1] = 999999;
@@ -869,6 +870,8 @@ void CalcSurfaceExtents(msurface_t *s)
 		else
 			v = &loadmodel->vertexes[loadmodel->edges[-e].v[1]];
 
+		VectorAdd(middle, v->position, middle);
+
 		for (j = 0; j < 2; j++)
 		{
 			// FIXED: loss of floating point
@@ -884,15 +887,25 @@ void CalcSurfaceExtents(msurface_t *s)
 		}
 	}
 
+	VectorScale(middle, 1.0f / s->numedges, middle);
+
 	for (i = 0; i < 2; i++)
 	{
 		bmins[i] = (int) floor(mins[i] / 16);
 		bmaxs[i] = (int) ceil(maxs[i] / 16);
 
 		s->texturemins[i] = bmins[i] * 16;
 		s->extents[i] = (bmaxs[i] - bmins[i]) * 16;
+
 		if (!(tex->flags & TEX_SPECIAL) && s->extents[i] > MAX_SURFACE_TEXTURE_SIZE)
-			Sys_Error("%s: Bad surface extents", __func__);
+		{
+			int surfID = s - loadmodel->surfaces;
+			Sys_Error("%s: Bad #%d surface extents %d/%d on %s at position (%d,%d,%d)",
+				__func__, surfID, s->extents[0], s->extents[1],
+				tex->texture->name,
+				(int)middle[0], (int)middle[1], (int)middle[2]
+			);
+		}
 	}
 }