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Help with if / else statement
Ok, I’m just messing around with expressions and just testing some stuff, and am working on simulating gravity.
Then I decided that when my object reached the bottom of the screen, it would go back to the top and stay there. This is what I have, but it doesn’t work.
x = transform.position[0];
y = transform.position[1]; // y is equal to ft or metersm = thisComp.layer(“Null 1”).effect(“mass”)(“Slider”);
g = thisComp.layer(“Null 1”).effect(“gravity”)(“Slider”);yFall = y + m * g;
if ( yFall >= thisComp.height)
{
yFall * 0
} else {
yFall
};[x, yFall]
I was messing with if/else statements earlier last week, but I have to be missing something.
Thanks in advance…
Stephen =]
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1 Reply
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Are you animating the sliders ?
The problem is that if you’re using the sliders to set fixed values, nothing changes from frame to frame, so there’s no movement.
You need to factor in time to animate this.for example:
yFall=y + (g/2)*(time*time);
wich is the classic Newtonian equation for a falling body.
Mass has nothing to do with theoretical falling, as you might remember from physics class. Or from the astronaut dropping a feather and a hammer on the moon (how did they fake THAT ? 😉 )You may however want to figure in air-resistance and terminal velocity which do factor in Mass.
Let me know if that accurately a simulation is important, and we’ll try to solve it using the info at this url:https://en.wikipedia.org/wiki/Drag_(physics)#Velocity_of_a_falling_object
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