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 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 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
> > 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
> >>>
> >>> 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
> >>> 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 th
