Creating an ocean of text layers, all reacting to a displacement map

[Dan Ebberts]

I don’t think the amount of luminance change from one frame to the next is going to have the right relationship to the angle. It seems like you could use the expression you used to find the top of the wave, but do it some distance to the left and right of the text’s position. Then with p1 and p2, you could derive the angle. Something like this (just shooting from the hip here):

delta = p2 – p1;
radiansToDegrees(Math.atan2(delta[1],delta[0]))

Dan

[Chris Mellor]

Thanks so much Dan! Although I am not quite sure how arctangent2 works… it works! Unfortunately these expressions are now causing AE to act really buggy. Sometimes the program crashes, but more often, I get a “Timeout while waiting for engine” error. Sounds to me like there is some kind of infinite loop problem, but I can’t imagine where.
If someone could look over my code and give me some feedback, that would be great. Maybe there are some redundancies or simple syntax errors I am overlooking.
Here is the code for the Position value of my word layer, remember this is one layer meant to be duplicated 500+ times:
leader = thisComp.layer("Attractor"); // null layer

// spacial offset from null
seedRandom(index, true);
offsetX = random(0,20)*thisComp.layer("Spacial Slider").effect("X")("Slider")*thisComp.layer("Spacial Slider").effect("XYZ")("Slider");
offsetY = random(-20,20)*thisComp.layer("Spacial Slider").effect("Y")("Slider")*thisComp.layer("Spacial Slider").effect("XYZ")("Slider");
x = leader.position[0] + offsetX*time; // the *time makes it so it is always moving, so the atan2() in the rotation expression is never dividing by 0
y = leader.position[1] + offsetY;

// z bump
zMin = thisComp.layer("Wave Height Sliders").effect("zMin")("Slider");
zMax = thisComp.layer("Wave Height Sliders").effect("zMax")("Slider");
target = thisComp.layer("Turbulence Layer");
samplePoint = [Math.abs(x),Math.abs(y)];
sampleRadius = [5,5];
rgb = target.sampleImage(samplePoint, sampleRadius);
lum = rgbToHsl(rgb)[2];
offsetZ = ease(lum, 0, 1, zMin, zMax)*thisComp.layer("Spacial Slider").effect("Z")("Slider");
z = leader.position[2] + offsetZ;

[x, y, z]

and the zRotation expression looks like this:
p1 = position;
p2 = position.valueAtTime(time-thisComp.frameDuration*5);
delta = p1-p2;

radiansToDegrees(Math.atan2(delta[2],delta[0]))

Does this all make sense? Is there a smarter way I could write this so AE doesn’t get confused reading it??

-Chris

[Dan Ebberts]

I wasn’t suggesting that you sample the position at the previous frame, but rather, sample the luminance a small distance to the left and right of the layer’s position (at the current frame) so you can then use Math.atan2() to calculate the slope of the wave for that layer.

Let me ask you this–does your visible wave just consist of the text layers? If so, I think I might have a much simpler solution for you.

Dan

[Chris Mellor]

Yes, I’m simply trying to simulate a large body of water using words. I got very close with Trapcode Form by creating a plane of sprites (my words) and applying the displacement map to it to simulate the subtle waves. But Form won’t allow the words to rotate as they move along the waves so I am using these expressions instead.

I would love to know if there is a simpler solution because all of these expressions are severely affecting AE… I am getting the timeout error almost every time I RAM preview now.

-Chris

[Dan Ebberts]

OK–play around with these. You’ll probably want to tie the variables to sliders (it’s important that they match in the two expressions).


// *** position ***

maxX = 300;
maxZ = 100;
maxY = 100;
tMult = .25;
xMult = .25;
zMult = .25;

seedRandom(index,true);
x = random(-maxX,maxX);
z = random(-maxZ,maxZ);
y = maxY*noise([x*xMult,z*zMult,time*tMult]);

value + [x,y,z]

// *** z rotation ***

maxX = 300;
maxZ = 100;
maxY = 100;
tMult = .25;
xMult = .25;
zMult = .25;

deltaX = 10;
rMult = .15;

seedRandom(index,true);
x = random(-maxX,maxX);
z = random(-maxZ,maxZ);
y1 = maxY*noise([(x-deltaX)*xMult,z*zMult,time*tMult]);
y2 = maxY*noise([(x+deltaX)*xMult,z*zMult,time*tMult]);

rMult*radiansToDegrees(Math.atan2(y2-y1,2*deltaX))


Dan