[Xavier Gomez]

I confirm, steep is the slope….

[Xavier Gomez]

!!! I had seen this option but never used it. Thank you.

[Xavier Gomez]

May i ask then how you save the xml bit as a .ffx file ?

Never done that before.

By the way i started reading the DSK guide… WHAT A PAIN !@%!

[Xavier Gomez]

Well, i just downloaded SDK and its guide. Will see. Hopefully creating a void plug-in is not that hard !

Thank you for your answers.

[Xavier Gomez]

I mean group of sliders inside a given effect (for instance there is is group called “Transform” and inside this group there are many sliders, another group called “Material Options” with several sliders and so on…, all of these groups inside the same effect).

I’m using CS5.5, i can still use Pixel Bender. But if you think PB is not a good solution, do you have any idea of how i could make some kind of “pseudo effect” that organizes expressions controls (sliders, boxes, dropdownmenus, etc) into groups, with the correct names, and referentiable in a script ?

[Xavier Gomez]

Try this:

max = Math.max(Math.max(a,b),c);
min = Math.min(Math.min(a,b),c);
if (a < max){
if (a > min) mid=a else mid=Math.min(b,c);
}
else {mid = Math.max(b,c)};
mid

It will hardly generalize to higher number of parameters but for just 3 it is ok.

[Xavier Gomez]

I dont know the answer to your question but at least i can save you some time. Line 2 of your expression cannot produce anything, you must have copied it wrong. It might be:

[position[0], position [1] + temp]

[Xavier Gomez]

God ! thx a lot ! valueAtTime(time,false) is working so well !

pretty unintuitive though. I had initially used
Progression=myControl.property(“Progression”).valueAtTime(t,myControl);
thinking that setting preExpression to be ‘myControl’ would tell AE to look what’s there.
Anyway, works fine now.

For the auxialiary question, too bad, but that’s what i was expecting.
I’m writing a script that wanna be a plugin…

thank you again.

[Xavier Gomez]

I up this thread since i have the same question as its title, which is not fully answered: can a script read an expression ?

In my case, the script is taking into account some sliders values, calculates something with them, and returns “something”.
It’s working well when the sliders only have keyframes, but the expressions are not taken into account by the script. Is this a normal behavior and is there a way to pass by ?

I actually have another question, quite independant:
The built-in and third-party effects have comprehensive custom controls, for instance: X scale and Y scale are linked by default, checking a checkbox will enable a previously disabled option, etc.
Can one achieve this with a custom effect ? Can a script disable a slider? I tried .disable(), .hide() but apparently that only works for the UI palette: .disable() is not defined for my properties…

Hopefully i was clear. Thx in advance !

[Xavier Gomez]

Thank you, this indeed turns rotobezier ON.
However rotobezier gives poor result unless one inputs some already good enough values for the tangents.

In case someone faces the same problem in the future, I post below a short script based on some doc on Bezier interpolation found there: https://people.sc.fsu.edu/~jburkardt/html/bezier_interpolation.html. (sorry, can’t figure out how the link tool is working !)

This script assumes that what AE calls Bezier interpolation is really a Bezier interpolation (there are many other types of interpolations similar to Bézier). But it works very well so it should be the case, and the algorythm will vectorize properly most curves (smooth enough, curves with sharp variation like sin with very high frenquency require more vertices).
It creates 3 times more points than the number of vertices of the path (2/3 of these points are here to make sure that the path will walk through them). The funny numbers have their explanation in the doc linked above.

Note: this is just the bit of code needed to get the Vertex and Tangents arrays. The script won’t run as it is. To run it, one has to complete the input and add lines like:
var myLayer = app.project.activeItem.layer(1);
var myMask = myLayer.Masks.addProperty(“ADBE Mask Atom”);
myProperty = myMask.property(“ADBE Mask Shape”);
myPath = myProperty.value;
myPath.vertices = V_Array; myPath.inTangents = IT_Array; myPath.outTangents = OT_Array;
myPath.closed = CloseBoolean;
myProperty.setValue(myPath);
myMask.rotoBezier = rotoBezierBoolean;
(etc.)

function CurvePoint(u) { // the curve function
var x; var y;
x = ; // input function there
y = ; // input function there
return([x,y]);
}
function VectorNorm(X){ // optionnal, for more smoothing
return(Math.sqrt(X[0]*X[0]+X[1]*X[1]))
}
function Average(X,weightX,Y,weightY){ // optionnal, for more smoothing
var pX=weightX /(weightX+weightY);
var pY=weightY /(weightX+weightY);
return ( pX * X + pY * Y );
}

var Nvertex =....; // the number of vertex you want in your path
var u_min = ... ; // the min value for the curve parameter
var u_max = ... ; // the max value for the curve parameter

// some other parameters for the curve

var CloseBoolean = false; // true for a closed path, false for open
var SmoothBoolean = false;
var rotoBezierBoolean = false;
//
var P_Array=new Array();
var V_Array=new Array(); // the array of vertices
var iT_Array=new Array(); // the array of inTangents
var oT_Array=new Array(); // the array of outTangents
var newP=new Array();

for (i=0; i <= 3*Nvertex; i++) { // creates the array of ALL POINTS (the actual vertices + intermediary hidden control points)
u = u_min + i * (u_max-u_min)/(3*(Nvertex)); // for uniform parameter set. This should be adapted to the need.
P_Array[i] = CurvePoint(u);
}

for (i=0; i < Nvertex ; i++) { // builds the Vertex, inTangents and OutTangents arrays

// builds the Vertex Array
V_Array[i] = P_Array[3*i];

// builds the IN Tangents Array
if (i < 0) iT_Array[i] = ( 2*P_Array[3*i-3] - 9* P_Array[3*i-2] + 18*P_Array[3*i-1] - 11*P_Array[3*i] ) /6;
else{
if (CloseBoolean == false) iT_Array[0] = [0,0];
else iT_Array[0] = (2*P_Array[3*(Nvertex)-3] - 9* P_Array[3*(Nvertex)-2] + 18*P_Array[3*(Nvertex)-1] - 11*P_Array[0])/6;
}
// builds the OUT Tangents Array
if (i < Nvertex-1) oT_Array[i] = (-11* P_Array[3*i] + 18*P_Array[3*i+1] - 9*P_Array[3*i+2] + 2*P_Array[3*i+3])/6;
else{
if (CloseBoolean == false) oT_Array[Nvertex-1]=[0,0];
else oT_Array[Nvertex-1] = ( -11* P_Array[3*(Nvertex-1)] + 18*P_Array[3*(Nvertex-1)+1] - 9*P_Array[3*(Nvertex-1)+2] + 2*P_Array[0] ) /6;
}
}

//some optionnal smoothing
if (SmoothBoolean == true){
Temp= new Array();
var o_norm;
var i_norm;
for (i=0; i < Nvertex ; i++) {
o_norm=VectorNorm(oT_Array[i]);
i_norm=VectorNorm(iT_Array[i]);
if (o_norm+i_norm > 0){
Temp= Average(oT_Array[i],o_norm,-iT_Array[i],i_norm)
oT_Array[i]=(1+(o_norm-i_norm)/(o_norm+i_norm)) * Temp;
iT_Array[i]= -(1-(o_norm-i_norm)/(o_norm+i_norm)) * Temp;
}
}
}