Keyframes & Expressions

[Nerox]

Hi,

I wonder, is there a way to change the value of a keyframe using a expression?

I'm using Chops to offset a animation curve, this curve is used to randomly animate copied objects (blocks that jump up). This curve is created using 3 keyframes on the channel node in Chops.

I have my reasons to have them start from 0 on the Y axis and 'land' on 0.1 for instance, I could change the keyframes by hand. The only issue is that I use a math Chop to scale the curve randomly (different jump height), this only affects the 'key frames' which value is more than zero. But if the last keyframe is not on 0, like I would like, than it's also affected by the so called 'height Scale' and I'm no longer able to exactly determ on which position in Y the box will 'land'.

As you can see in the example file the landing position is related to the jump hight, because the end keyframe is affected by the scaler (or math Chop in this case). In this case the difference is minimal, as seen form the side, but you'll get the point.

If I was able to change only the middle keyframe (which controls the height), instead of using a math Chop I could get rid of this side effect.

Any idea's?

jumpExample_V01.hip

[anim]

what about defining your jump curve as starting at 0 ending at 0

then use math CHOP to vary height by multiplying/changing its range as you have

then add second curve which goes from 0 to desired end height

look ad the file for what i mean by that

(i do not think that there is direct way to affect certain keyframes by expression, but you can use multiple chnstant CHOPs to create points in value and time and then plug them into interpolate CHOP)

jumpExample_V01_fix.hip

[beeemtee]

just a quick tip. check hou.Keyframe object in the HOM reference. there is also chkey expression in hscript but that seems much more limited, for example i don't see any flags to set the time of the key.

cheers

bmt

[Nerox]

what about defining your jump curve as starting at 0 ending at 0

then use math CHOP to vary height by multiplying/changing its range as you have

then add second curve which goes from 0 to desired end height

look ad the file for what i mean by that

(i do not think that there is direct way to affect certain keyframes by expression, but you can use multiple chnstant CHOPs to create points in value and time and then plug them into interpolate CHOP)

That's very clever, haven't looked at it this way. I'm making my first steps with Chops, jet it's just a total diffent state of mind.

Thanks!