MobEntityPathVisualizer.java

@Mod.EventBusSubscriber(modid = YOURMOD.MOD_ID)
    public static class ServerEvents {

        @SubscribeEvent
        public static void onLivingUpdateEvent(LivingEvent.LivingUpdateEvent event) {
            LivingEntity le = event.getEntityLiving();
            if (le instanceof MobEntity) { // only MobEntity has a Navigator, so this includes most entities
                PathNavigator navi = ((MobEntity) le).getNavigator();
                if (le.world instanceof ServerWorld && le.world.getGameTime() % 10 == 0) { // only generate every 0.5 seconds, to try and cut back on packet spam
                    Path path = navi.getPath();
                    if (path != null) {
                        for (int i = path.getCurrentPathIndex(); i < path.getCurrentPathLength(); i++) {
                            //get current point
                            BlockPos pos = path.getPathPointFromIndex(i).func_224759_a(); 
                            //get next point (or current point)
                            BlockPos nextPos = (i+1) != path.getCurrentPathLength() ? path.getPathPointFromIndex(i+1).func_224759_a() : pos; 
                            //get difference for vector
                            BlockPos endPos = nextPos.subtract(pos);
                            //render pathpoints
                            ((ServerWorld) le.world).spawnParticle(ParticleTypes.HAPPY_VILLAGER,
                                    pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5, 0,
                                    0, 0, 0, 0);
                            //send a particle between points for direction
                            ((ServerWorld) le.world).spawnParticle(ParticleTypes.END_ROD,
                                    pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5, 0,
                                    endPos.getX(), endPos.getY(), endPos.getZ(), 0.1);
                        }
                        // render end point
                        BlockPos pos = navi.getTargetPos();
                        ((ServerWorld) le.world).spawnParticle(ParticleTypes.HEART,
                                pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5, 0,
                                0, 0, 0, 0);
                    }
                }
            }
        }
    }