Thanks. The TD i have planned to code may contain lot of direction changes so i think i will use homing missile, i have already started to code a kind of homing missile firing system using vector thanks to numpy and it s not too bad.
Le 25 juil. 2011 à 06:07, Jake b <[email protected]> a écrit > This calculates to shoot in the path of the target. > Like how you throw a football, to lead the catcher. Instead of where they are > at that second. > > For tower defense, some Bullets fly fast enough you don't have to lead. > > Slower bullets fire, then every frame you: > Move the bullet location toward target. ( without leading ) > Thats simple homing, but you can skip the steering part a homing missile has. > The trajectory will end up curving, depending on speeds used. > > For a straight line you will have to lead. But leading will miss if target > chamges direction or speed. > > On Saturday, July 23, 2011, Joe Ranalli <[email protected]> wrote: > > 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 :-) > >>> > >> > > > > > > -- > Jake
