• Create Account

Direction vector

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

3 replies to this topic

#1cold_heats_.--.  Members

127
Like
0Likes
Like

Posted 24 July 2012 - 08:39 AM

Me again, with another question.
Suppose I have two sprites on screen, sprite A at position (3,5) sprite B at (8,10).I want sprite B to move towards A with the speed of 1 pixel per second.
So I calculate the direction vector from B to A : dir=B-A=(5,5) . Its length "L" will be sqrt(5*5+5*5)=sqrt(50).
I normalize it dir=(5/L, 5/L).The components will now be : dir =(0.7,0.7) .I multiply each by the speed, but in this case they will stay the same.
I update the new position B(8.7,10.7) but the components will have to be type casted to int when I call SDL_BlitSurface().So going by my logic, sprite B will always stay at the same position.
What am I doing wrong ?

#2Olof Hedman  Members

5705
Like
0Likes
Like

Posted 24 July 2012 - 08:48 AM

Will it?
next frame, the values should be (9.4,11.4) and at that point it will have moved.
Unless you for some reason destroy the value when you typecast.

Edited by Olof Hedman, 24 July 2012 - 08:49 AM.

#3cold_heats_.--.  Members

127
Like
0Likes
Like

Posted 24 July 2012 - 10:43 AM

Gosh, I feel so stupid. Thanks for enlightening me xD !

#4Farraj  Members

152
Like
0Likes
Like

Posted 24 July 2012 - 11:38 AM

lol, I read 2/3 of your post and thought this guy knows what he's talking about. What could be the problem

Same answer as the above. Just keep looking, it will move

Good luck man

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.