improved the clipping bugfix

src/libcore/triangle.cpp

@@ -126,20 +126,24 @@ AABB Triangle::getClippedAABB(const Point *positions, const AABB &aabb) const {
 		for (int j=0; j<3; ++j) {
 			/* Now this is really paranoid! */
 			double pos_d = vertices1[i][j];
-			Float pos_f = (Float) pos_d;
+			float pos_f = (float) pos_d;
 			Float pos_roundedDown, pos_roundedUp;
 
-#if defined(SINGLE_PRECISION)
-			pos_roundedUp = nextafterf(pos_f, 
-				std::numeric_limits<float>::infinity());
-			pos_roundedDown = nextafterf(pos_f, 
-				-std::numeric_limits<float>::infinity());
-#else
-			pos_roundedUp = nextafter(pos_f, 
-				std::numeric_limits<float>::infinity());
-			pos_roundedDown = nextafter(pos_f, 
-				-std::numeric_limits<float>::infinity());
-#endif
+			if (pos_f < pos_d) {
+				/* Float value is too small */
+				pos_roundedDown = pos_f;
+				pos_roundedUp = nextafterf(pos_f, 
+					std::numeric_limits<float>::infinity());
+			} else if (pos_f > pos_d) {
+				/* Float value is too large */
+				pos_roundedUp = pos_f;
+				pos_roundedDown = nextafterf(pos_f, 
+					-std::numeric_limits<float>::infinity());
+			} else {
+				/* Double value is exactly representable */
+				pos_roundedDown = pos_roundedUp = pos_f;
+			}
+
 			result.min[j] = std::min(result.min[j], pos_roundedDown);
 			result.max[j] = std::max(result.max[j], pos_roundedUp);
 		}