【正文】
en 10 zombies are killed, show a message “a big wave of zombies is approaching”. 3. Highlight a spirit when it is selected (say, when update a plant) 4. Each Visible object has a Zpos property, by which the renderQueue to decide the order to render. ., the order in the level from far to near can be: scenespirit in the 6th rowspirits in the 5th row…spirits in the 1st rowplant storemenu 5. Block and unblock: Inside the PlantStore the user clicked “LevelMenu”. This is , since LM will be above of the PS in the TaskQueue and thus can block the PS and the spirit. A difficult case: In one frame of a level, if the user both clicked “PlantStore” and “LevelMenu”. Therefore it’s possible that the PS is above the LM in the TaskQueue. I feel that the block object should always block all the unblock object. Therefore, a simple way for this issue is to only allow block object to be add above on the other block objects