PolygonBucket: dont test bbox visibility with overzoom > 2

- workaround: seems there can be some overflow in GLMatrix.prj2d()

vtm/src/org/oscim/renderer/bucket/PolygonBucket.java

@@ -337,6 +337,7 @@ public final class PolygonBucket extends RenderBucket {
 				if (area.fadeScale > 0 && area.fadeScale > zoom)
 					continue;
 
+				if (div > 0.5) {
 					/* project bbox of polygon to screen */
 					v.mvp.prj2D(pb.bbox, 0, box, 0, 4);
 
@@ -351,24 +352,26 @@ public final class PolygonBucket extends RenderBucket {
 						}
 						out |= o;
 					}
-
 					/* Check if any polygon-bucket edge intersects the screen.
-				 * Also check the very unlikely case where the view might be
+					 * Also check the very unlikely case where the view might
+					 * be
 					 * completly contained within box */
 					if ((out != 0) && (out != 0xF)) {
-					mScreenClip.clipStart(box[0], box[1]);
+						mScreenClip.clipStart(box[6], box[7]);
+						out = 0;
+						for (int i = 0; i < 8 && out == 0; i += 2)
+							out = mScreenClip.clipNext(box[i], box[i + 1]);
+
+						if (out == 0) {
+							//log.debug("out {}\n {}\n {}", out, Arrays.toString(pb.bbox), Arrays.toString(box));
 
-					if (mScreenClip.clipNext(box[2], box[3]) == 0 &&
-					        mScreenClip.clipNext(box[4], box[5]) == 0 &&
-					        mScreenClip.clipNext(box[6], box[7]) == 0 &&
-					        mScreenClip.clipNext(box[0], box[1]) == 0) {
 							//	log.debug("outside {} {} {}", out,
 							//	          Arrays.toString(box),
 							//	          Arrays.toString(pb.bbox));
 							continue;
 						}
 					}
-
+				}
 				if (mClear) {
 					clearStencilRegion();
 					/* op for stencil method polygon drawing */