Yes, it will work as long as the target doesn't change direction. On Sat, Jul 23, 2011 at 1:13 PM, Nathan BIAGINI <[email protected]>wrote:
> Ok. Yeah it's more explicit, thanks to take time to rewrite it. So it will > works in case of really simple tower defense graph, where the target always > progress to a point A to a point B? > > > 2011/7/23 Joe Ranalli <[email protected]> > >> Yes. >> >> So to be more explicit: >> >> 1 Calculate the distance between the source and the target. >> 2 Calculate the time for the bullet to move that distance (i.e. by >> dividing this distance by the bullet velocity) >> 3 Calculate newposition (multiply the target velocity by the time >> calculated in the previous step, add to original target position) >> 1a Recalculate the distance between the source and newposition >> 2a Recalculate the time for the bullet to move from the source to >> newposition (i.e. divide the new distance by the bullet velocity) >> 3a Recalculate newposition using this new time (multiply the target >> velocity by the new time calculated in the previous step, add to original >> target position) >> >> >> >> >> On Sat, Jul 23, 2011 at 12:55 PM, Nathan BIAGINI >> <[email protected]>wrote: >> >>> Ok so thanks all for all your replies i will work with all that. I don't >>> know already if i want to use homing missile style which seems to be easier >>> to code or to use an algorithm to fire straight to the right spot. >>> To be honest, i'm not native english speaker and it's not always easy to >>> figure out what you really mean but i'm doing my best. >>> >>> I just want to ask you Joe about your algorithm : >>> >>> >>> If you want to have the bullet go straight to the right spot, you need >>>> to: >>>> 1) calculate how long the bullet will take to get to the enemy >>>> 2) calculate where the enemy will be at that time (newposition) >>>> 3) calculate how long it will take the bullet to get to newposition >>>> 4) recalculate newposition based on the new time >>>> >>> >>> Ok so i think the first step is pretty clear to me, the step 2 too but i >>> don't understand the step 3. My english isn't the best i repeat so... i have >>> to calculate how long the bullet will take to go to 'newposition'. So i will >>> get a new time value and then i need to recalculate newposition based on >>> this new time? And fire at 'newposition'? And also, to be sure, >>> 'newposition' is the virtual position of the target after the time taken by >>> the bullet to hit it, right? >>> >>> Sorry if it seems to be straigh forward to you :-) >>> >>> Of course i will try others way like Lee suggested me. >>> >>> Thanks. >>> >>> 2011/7/20 Joe Ranalli <[email protected]> >>> >>>> It depends what you're trying to do. >>>> >>>> If you draw the straight line between the tower and the enemy and use >>>> that vector to translate a bullet each tick, the bullets might miss the >>>> enemy. Think about it this way, the bullet moves 2 steps toward the enemy, >>>> then the enemy moves 1 step, then the bullet moves 2, etc. Because the >>>> enemy moves the bullet will have to change its direction through the >>>> flight. So you could calculate the direction vector between the bullet and >>>> the enemy every tick and have the bullet move that direction. That would >>>> make the bullets kind of arc to the target. >>>> >>>> If you want to have the bullet go straight to the right spot, you need >>>> to: >>>> 1) calculate how long the bullet will take to get to the enemy >>>> 2) calculate where the enemy will be at that time (newposition) >>>> 3) calculate how long it will take the bullet to get to newposition >>>> 4) recalculate newposition based on the new time >>>> >>>> Technically you could iterate that repeatedly until newposition >>>> converges. Practically, iterating once probably gets you close enough >>>> unless the movement is extremely complicated. >>>> >>>> >>>> On Wed, Jul 20, 2011 at 9:14 AM, Nathan BIAGINI >>>> <[email protected]>wrote: >>>> >>>>> Hi everyone, >>>>> >>>>> i would like to know what are the common way to handle "trajectory" in >>>>> a 2d game. In fact, i think of writing a tower defense game and i wonder >>>>> how >>>>> to handle the trajectory of the missile launch by the towers. I though of >>>>> getting the pos of the tower and the target and create a vector between >>>>> this >>>>> two entitites to make a sprite translation of this vector but there is >>>>> maybe >>>>> some tricky stuff to do it. >>>>> >>>>> Thanks in advance and happy game making all :-) >>>>> >>>> >>>> >>> >> >
