Re: FLASH: Velocity Control

[Marc Hoffman]

At 09:08 PM 3/4/99 -0600, you wrote:

>Marc Hoffman said:

>>There's been some talk here lately about scrolling text and reversing movie

>>playback. Today I made a little speed control for a MC of a car driving.

>>You can see it about halfway down the page at

>>http://www.jps.net/dartfrog/sampler/

>

>Care to share the tricks of the trade? Looks like an interesting effect...

>

>Troy.


The throttle consists of seven identical buttons plus a throttle movie clip

(MC). The throttle MC is what you first see, but as soon as you mouse over

one of the buttons it disappears.  The seven buttons are invisible in the

UP state, but on mouseover each shows the throttle.  Their hit areas are

each wedge-shaped so they fit like pieces of a pie and on mouseover each

shows a different throttle position.


The car movement has several nested MCs.  At the deepest nested level is a

MC of the car rocking, with a rocking shadow under it.  The man inside the

car is a MC that has two frames: in one he faces right, in the other he

faces left.  The MC of the car rocking was dropped into another MC, with an

instance name "car," that motion-tweened the rocking car MC across the

stage (initially I built this on the stage, then converted it to the MC).


Each of the throttle buttons is programmed a bit differently.  On mouseover

they all tell the initial throttle MC to go blank, and on mouse rollout

they tell it to reappear.  They also send TellTargets to a MC called

"speed," which is responsible for controlling the forward and back motion

of the MC "car."  For example, the button to the left of center sends

"speed" to a frame that TellTargets "car" to go to the previous frame.

"Speed" issues this command, then plays to its next frame, where it

receives a command to go back a frame.  This loop continues until Mouse

Rolloff, which tells "speed" to go to park, a frame that simply tells "car"

to stop. The next button to the left accomplishes a similar task, only

"speed" goes to a pair of frames, the first of which issues two TellTargets

for "car" to go to the previous frame.  The farthest left button results in

five "go to previous frame" commands in a single frame of "speed," which

will loop as long as mouseover continues.  The buttons to the right of

center behave similarly except they target loops within "speed" that

generate "go to the next frame" actions.  Finally, every "forward" button

tells the MC of the driver to go to where he's facing right, and every

"reverse" button sends him to a frame where he faces left.


A lot of what I do is engineered backwards.  That is, I'll tween a car

across the stage, then turn the car into a MC, then edit the elements of

the MC so that THEY are MCs.  So I go from big to small, from stage to

symbol to nested symbol. That way I can start with the stage layout and not

have to resize and align elements after the fact.



Marc Hoffman

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

marcdartfrogmedia [dot] com (mailto:marcdartfrogmedia [dot] com)

My home site is now featured in Ken Milburn's book, Flash 3 Web Animation f/x

and Design. Play a virtual marimba there: <www.dartfrogmedia.com/dartfrog>.

View my Flash3 samples: <http://www.jps.net/dartfrog/sampler>.

Read about Flash: <http://www.jps.net/dartfrog/sampler/flashinf>


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