[solved]How do I make elliptical motion with offset?

  • I'm trying to figure how to make ellptical motion in following path:

    I've uploaded a .capx here, but it does circular motion, not ellitpical with offset, I'm looking a solution, thanks!

  • Like this? I'm still on r195 I'll need to upgrade

    https://dl.dropboxusercontent.com/u/139 ... cle_e.capx

  • Are you looking for elliptical motion, or motion along the path in your image there? Both are very different

  • Noncentz705 sqiddster the image is clear, I don't need like that:

    I had no idea what's name of this form, I would say elliptical motion with offset for top line and bottom line, maybe rectangle with rounded corners

  • i think you could make it using standard "circular" motion with sin and cos and little switch. When object is on top just move it forward and after some time turn on circular motion. After reaching bottom turn it off and let it go forward. Then turn it on again etc.

  • As shinkan, just make the y distance longer than the x.

  • Attached is a exact way to do a rounded path like the op.

        * |*  *  *  *  *  *| *
     *    |                |    *
    *     |       o        |     *
    *     |                |     *
     *    |                |    *
        * |*  *  *  *  *  *| *
    
    |     |\               |
    +-----+ +--------------+
     radius       space[/code:15y1qd5m]
    
    You can think of each piece of the path like a lerp from one point to another.
    left side:
    x = center.x - space/2 + radius*cos(90+180*t)
    y = center.y + radius*sin(90+180*t)
    
    top:
    x = center.x + 0.5*space*lerp(-1,1, t)
    y = center.y - radius
    
    right side:
    x = center.x + space/2 + radius*cos(-90+180*t)
    y = center.y + radius*sin(-90+180*t)
    
    bottom:
    x = center.x + 0.5*space*lerp(1,-1, t)
    y = center.y + radius
    
    where t is a number from 0 to 1.
    
    Now all that needs to be done is depending on the distance traveled choose the correct equations and t value.
    We first start with the distance traveled:
    distance = speed * time
    
    Next we need to know the lengths of the pieces.
    The top and bottom are easy with a length of "space".
    The left and right can be found with the following equation:
    arc length = radius * (angle in radians)
    Which ends up as pi*radius for each.
    
    With the above the total length = 2*pi*radius+2*space
    
    To choose the correct equations we compare the distance traveled,
    
    0 to pi*radius is the left side.
    pi*radius to pi*radius+space is the top.
    pi*radius+space to 2*pi*radius+space is the right.
    2*pi*radius+space to 2*pi*radius+2*space is the bottom.
    
    Then we find a t (0..1) value for the side with:
    If left then t = distance/pi*radius
    If top then t = (distance-pi*radius)/space
    If right then t = (distance-pi*radius+space)/(pi*radius)
    If bottom then t = (distance-2*pi*radius+space)/space
    
    As a final step we want it to loop so we can use the % operator with the total length to do that.
    distance = (speed*time)%(2*pi*radius+2*space)
    
    If speed is negative then we need to do effectively this:
    ((a%b)+b)%b
    
    In the capx I used a function for that.
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  • R0J0hound delivers the classic solution.

    Thanks a lot, it's solved now.

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