Kurt Griffin wrote:
> Don't use a repeat loop. You can use a frame loop, but that relies on frame
> rate. A better way is to drive your animation with a timeout object.
>
> Normally, I'd leave you with that advice and let you work through it, but I
> happen to have written a behavior that will move a sprite in a straight line
> to a destination point
> I'm sure there are ways to optimize... that's a hint, people - I'd love to
> see ways to improve it.
Hey Kurt,
Here is another take on the animation behaviour. It is time based but doesn't use
timeout objects, instead it calculates the change in time at each enterframe and uses
that to position the sprite.
Also have a look at the use if the vector in this approach (difference between
destination and origin) this really eliminates the need for working out the number of
steps the animation will take as well as calculating the direction (taken care of by
the vector).
Finally this behaviour allows you to differentiate between speed as in total time to
get to the destination or speed as in the rate (pixels per second) it travels to get
to the destination. This behaviour is not un-like the slide in out behaviour in the
libraries palette. The one
that comes with director is more detailed and has more error checking.
let me know what you think,
Rob
---linearMotionTimeBased behaviour---
property pOrigin
property pDestination
property pSpeed
property pSpeedType
property pMotionInit
property pMotionVector
property pStartTime
property pTravelTime
property pInMotion
on getPropertyDescriptionList me
pdl=[:]
if the currentSpriteNum>0 then
pdl[#pOrigin]=[#comment:"Origin point", #format:#point, #default:point(sprite(the
currentSpriteNum).locH, sprite(the currentSpriteNum).locV)]
pdl[#pDestination]=[#comment:"Destination", #format:#point, #default:point(0,0)]
pdl[#pSpeed]=[#comment:"Speed (msec or pixels/sec):", #format:#integer,
#default:1000]
pdl[#pSpeedType]=[#comment:"Speed type:", #format:#symbol, #default:#totalTime,
#range:[#totalTime, #pixelsPerSec]]
pdl[#pMotionInit]=[#comment:"AutoStart", #format:#boolean, #default:0]
end if
return pdl
end
on beginSprite me
if pMotionInit then me.startLinearMotion()
end
on startLinearMotion me
pMotionVector=pDestination-pOrigin
if pSpeedType=#pixelsPerSec then
distance=sqrt(power(pMotionVector.locH,2)+power(pMotionVector.locV,2))
pTravelTime=distance/pSpeed*1000
else
pTravelTime=pSpeed
end if
pStartTime=the milliseconds
pInMotion=1
end
on enterFrame me
if pInMotion then
dTime=the milliseconds-pStartTime*1.0
if dTime>pTravelTime then
newLoc=pDestination
pInMotion=0
else
newLoc=pOrigin+dTime/pTravelTime*pMotionVector
end if
sprite(me.spriteNum).loc=newLoc
end if
end
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