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  1. #1
    Registered User
    Join Date
    Jun 2006
    Posts
    1

    normal path for a ball

    Dears
    I want to move a ball from (x1,y1) to (x2,y2). but I need to ball's path look likes noram path same as real world,

    also there are different LCDs in nokia phones.
    I don't know how will I change the ball's x,y for moving from x1,y1, to x2,y2.

    I appreciate any comments.

    Saeed.

  2. #2
    Super Contributor
    Join Date
    Apr 2003
    Location
    USA, CA
    Posts
    7,191

    Re: normal path for a ball

    What do you mean by normal? Parabolic curve (like throwing a ball)? Or friction slowing down a ball rolling on a surface?

    It is possible to calculate the real world pysics in to the equation, it is just matter of what you are trying to achieve...

    Hartti

  3. #3
    Registered User
    Join Date
    Mar 2005
    Location
    Palghar, Mumbai
    Posts
    8

    Re: normal path for a ball

    I don't know what you want to do, but I have successfully done a tennis ball animation on mobile, which very close to real world animation.

    1. Take a ball in 3D space
    2. Apply diff. forces on the ball
    3. Find out velocity and update position of ball
    4. Take a projection to 2D space (viewport)
    5. Display the ball on projected co-ordinates.

    Hope this helps.

  4. #4
    Registered User
    Join Date
    Jul 2006
    Location
    Berlin
    Posts
    25

    Exclamation Re: normal path for a ball

    if the ball is thrown you can calculate the balls positions for a given time after start and a given strength (means a starting velocity) and a given alpha (starting angle counterwise beginning at 3 o'clock) with the following equation

    x = strength * time * cos(alpha)
    y = -(g/2) * t * t + strength * time * sin(alpha)

    keep in mind that operating at pixels in steps (time) can result in a very different new position (delta is bigger than recognizable, e.g. ball jumps out of the view) or very small delta (smaller than 1 pixel, so that the movement is not recognizable too). use a clever time base - time step combination to avoid these.

    keep in mind that midp 2.0 doesn't know floats, you have to hardly work around this fact for a midp 1.0 device

    regards ray()

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