effects starting too soon

[sabina]

Hi again. I'm trying to make a scene where a house light blinks on at a specific time, and a door opens at a specific time to reveal the inside of the house. I'm having a problem with these effects because instead of happening abruptly, later in the scene as I want them to, they start happening slowly from the beginning of the animation, and complete at the point where I actually wanted them to begin. For example, the door begins to slowly swing open from the beginning of the animation, rather than suddenly opening fairly quickly at the point I set. How do I make it so the effect will wait until I want it to begin? (hope this makes sense) ~ Sabina

[slowtiger]

You need to create a key in the timeline first where the action should start.

[sabina]

I have a key at the point where I want the effect to begin, but somehow the effect keeps starting from the beginning, even though I have not made a key at the beginning, slowly opening the door the whole time, until it reaches the key I made further on, where the effect completes. I've tried setting a key at the very beginning as well, where the door is completely closed, and I've tried without a key at the beginning, but this makes no difference.

[heyvern]

... slowly opening the door the whole time, until it reaches the key I made further on, where the effect completes...

Think about this slowly. There is ALWAYS a key at the beginning. That is the first key and is always where things start.

Movement based on key frames has a start frame and a completion frame. If the door is closed it needs to be keyed closed until you want it to open.

Imagine this is a time line. The first key is always frame 0, at the beginning. That key is "door closed". The second key frame later is ALSO CLOSED. The next key frame is door open. The door slowly opens BETWEEN the key frames.

Code: Select all

<closed---------------------------closed------------open----------------->

[sabina]

Thankyou for your replies. Apologies if I'm sounding dense , I DO have the two keys at the beginning (frames 0 and 1) where the door is closed, and another key at frame 256 where I want the door to suddenly open. But it still starts slowly opening at frame 2.

[heyvern]

Thankyou for your replies. Apologies if I'm sounding dense , I DO have the two keys at the beginning (frames 0 and 1) where the door is closed, and another key at frame 256 where I want the door to suddenly open. But it still starts slowly opening at frame 2.

If you want the door to open "instantly" on frame 256, not "quickly"... not "fast" but INSTANTLY open in one single frame, you change the key for the door open on frame 1 to a "step" key interpolation. It will probably look strange but it's up to you. The door will be closed until it hits a new key frame then it will INSTANTLY OPEN.

Back to your basic misunderstanding of key framing and animation. This happens a lot to people who don't have experience with it or just make incorrect assumptions. What is happening is the door opens slowly from frame 1 to frame 256. This is how key frames are suppose to work.

Key frame animation works by "in-betweening" the actions set "between" two frames. Frame 1 the door is closed. Frame 256 the door is open. The door with a standard smooth key frame (not step as described above), will slowly go from closed to open BETWEEN frames 1 and 256.

The key on frame 256 doesn't have any information to define a start and stop movement or animation. A single key can't tell the application I want to "quickly" open the door and have it take "6 frames" starting "here" and stopping "here". It's just one key frame with a specific "image" of the door "open". All that key can do on frame 256 is say "the door is open this much. period. Full stop. end of story I have nothing else to say".

In order to define a start and stop point of a movement is to define the start point with a key and and end point with a key.

If you wanted the door to START opening on frame 256 that key frame would be CLOSED, just like frame 1. Then "later" defined by the NEXT key you would have the door open. The space between those two keys determines the speed the door opens. Fewer frames between the keys and the door opens faster, more keys it opens slower. If you want the door FULLY OPEN on exactly frame 256, then you have to have the closed key frame a bit earlier, frame 225 for example. Then the key on frame 256 the door would be open. It would slowly open from frame 225 to 256.

The "step" interpolation described previously is a "one trick pony", it can only do one thing and that is instantly change to the pose or movement defined on that key. There is no way to change the speed or duration of that motion. It just happens instantly. This type of key interpolation would normally be used for specific types of actions like... blinking lights. Something that normally happens so fast you can't see the progression.

I would suggest reading up on animation basics. The concept of key frame animation you are having trouble with is... well... it's the first thing you have to know. It's lesson 1.

[slowtiger]

Copy the key from frame 1 to frame 256.

[sabina]

Got it. Thanks guys!