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pong -ish motion
I am trying to get a logo to bounce around the screen randomly for a few minutes and don’t want to keyframe. I’ve Dan Ebberts’ excellent expressions tutorials, but still don’t have the chops to make it happen. Can someone point me in the right direction?
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2 Replies
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Hi,
this is a bit different from Dan’s example wich uses random directions I believe.
A true-er pong motion if you will: ingoing angle is always the same as outgoing angle. Like those really old windows screensavers.
change the values in the first three lines.apply expression to position-param:
box=[20,20,300,220]; // box you want to stay in [x1,y1,x2,y2]
motion=[312,123]; // motion-vector in pixels per sond [x,y]
startpos=[160,120]; // startposition// calculations:
w=box[2]-box[0]; h=box[3]-box[1]; corner=[box[0],box[1]];
delta=motion*time; pos=startpos+delta-corner;
xx=pos[0]%(w*2); yy=pos[1]%(h*2);corner+[xx
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something went wrong, the last line was truncated:
box=[20,20,300,220]; // box you want to stay in [x1,y1,x2,y2]
motion=[312,123]; // motion-vector in pixels per sond [x,y]
startpos=[160,120]; // startposition// calculations:
w=box[2]-box[0]; h=box[3]-box[1]; corner=[box[0],box[1]];
delta=motion*time; pos=startpos+delta-corner;
xx=pos[0]%(w*2); yy=pos[1]%(h*2);corner+[xx,yy]
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