Forums Houdini Indie and Apprentice Select Point A, select another point, PontB above Point A. If no point found, select another PointA and repeat

Select Point A, select another point, PontB above Point A. If no point found, select another PointA and repeat

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craboom
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Joined: April 2015
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Hi there, what i´m trying to accomplish is to generate random pattern of different sizes for a corridor.

Let´s say, i have a grid.
I generate a point in the center of every primitive.

After that, i want to select a random PointA and imidiatly select another PointB wich is above PointA.
If there is no PointB above PointA then search for another random PointA and try again.

What i tried:

int pts[];
float seed;
@rand;

/////////////////////

pts = expandpointgroup(0, "*");
pos = point(0, "P", @ptnum);
seed = ch("seed");
@rand = floor(rand(seed)*@numpt);

//////////////////////

//s@pointName = "pointA";
@p0 = @ptnum;
@p1 = @ptnum+1;
@selected = 0;

////////////////////////
// for loop

for(int i=0; i <= len(pts); i++) {
    if(@p0 == @rand) {
        //setpointattrib(0, "selected", @rand, 1);
        i@selected = 1;  
        s@pointName = "pointA";
    } 
    else if(@p1 == @rand) {
        i@selected = 1;
        s@pointName = "pointB";
    } else {
        i@selected = 0;
        s@pointName = "none";
    }
}


//////////////
// foreach


// foreach(int pt; pts) {
//     if(@p0 == rand) {
//         @selected = 1;  
//         s@pointName = "pointA";
//     } else if(@p1 == rand) {
//         @selected = 1;
//         s@pointName = "pointB";
//     }
// }


///////////////////
// if (first approach

// if(@p0 == rand) {
//     @selected = 1;
// }else {
//     @selected = 0;
// }

@pts = len(pts);

//////////////////////
//  out messages

// printf("Length %d", len(pts));
// printf("Rand %d", rand);
// printf("CurrentP %d", @p0);
// printf("Test %d", rand);

All the things that are commented out where my first approaches, nothing of them worked.
My Wrangle Node runs over points, but letting it run over Detail didn´t work either.

I also tried to pts instead of @p0 into the foreach loopm but this does set teh @selected attribute to 1 on every point and not just in a single point.

I am very new to coding at all and i´m a bit stuck on this.

It seems that i misunderstand loops in Houdini in general.

If possible, please send me the longer way and easier to understand first so i can figure out what is happening, again, i am very new to coding and maybe i don´t understand everything at first, but i´ll try

Thanks a lot for every answer from you guys!!!
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craboom
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4 posts
Joined: April 2015
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I´ve talked to a programmer who´s not familiar with houdini but with C. He gave me a possible solution.

My question here is, is it nessecary that i have to create a random algorythm for this particluar thing or is there an even better / easier approach?

Here´s what he made for me: 

int pts[];
vector posi[];
int takenPositions[];
int height;
vector pos;
float seed;
int findTopPoint;

@rand;

/////////////////////

pts = expandpointgroup(0, "*");
pos = point(0, "P", @ptnum);
height = chi("height")-1;
findTopPoint = 0;


// random algorythm
seed = ch("seed");
@rand = floor(rand(seed)*@numpt);
if(@ptnum > 10){
    while(@rand < @ptnum && find(takenPositions, @rand)<0){
     
         push(takenPositions, @rand);
         seed +=1;
         @rand = floor(rand(seed)*@numpt);
    }
}
if(@ptnum == @rand){
    findTopPoint = 1;
}


// select point > y
float range = 0.001;
if(findTopPoint == 1){
    foreach(int pt; pts) {
        vector currentPos = point(0,"P", pt);
        if(
        currentPos.x <= @P.x + range && 
        currentPos.x >= @P.x - range &&
        currentPos.z <= @P.z + range &&
        currentPos.z >= @P.z - range &&
        currentPos.y > @P.y &&
        point(0,"selected", @ptnum) != 1
        ) {
            setpointattrib(0, "selected", pt, 1, "set");
            @selected = 1;
            height--;
            if(height<=0){
            break;
            }
        }
    }
}

I know this is not the best solution but it works and i have to figure out whatßs going on here and honestly, i also have to figure out how i can approach this, cause, like i said, i´m very new to coding, but i´m happy that i have something to work with
Still wondering if it´s the correct way doing it, thought there would be a nicer / easier solution
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craboom
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4 posts
Joined: April 2015
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no one can help me out with this?
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