Stepping Point move

[tamagochy]

Hi,

I have a curve with points. I need animation like this:

First point start moving and when it reaches of the position of the next point both points start moving and the same with next.

I remember that i already saw solution, but i cant find it. 

Thanks for helping!

[acey195]

The easiest solution would probably be using a "Carve" SOP,
although you could write your own solution in an attrib wrangle, if you really want to keep all the points.

[f1480187]

If you referring to this topic, solution was for vertical lines. Here is more general way:

// Point wrangle.
float u = (float) @ptnum / (@numpt-1.0);
float time = @Time;

if (u <= time)
{
    @P = primuv(0, "P", 0, time);
}

 

drag_by_u.hipnc

[acey195]

Slight improvement to the code (if you have multiple primitives ):

// Point wrangle. (works with multiple primitives)
int linVert = pointvertex(0, @ptnum);
int pr = vertexprim(0, linVert);
float u = (float) vertexprimindex(0, linVert) / (primvertexcount(0, pr) - 1.0);
float time = @Time;

if (u <= time)
{
    @P = primuv(0, "P", pr, time);
}

Also, if you want the movement to be linear, so the point moves with the same speed regardless of edge length, you can go more complex, like:

//Primitive wrangle
int pts[], i, j;
float segLens[], progress, segProgress;
vector ps[];

pts = primpoints(0, @primnum);
resize(ps, @numvtx);
resize(segLens, @numvtx -1);

for(i = 0; i < @numvtx; i++)
    ps[i] = point(0, "P", pts[i]);

for(i = 0; i < (@numvtx - 1); i++)
    segLens[i] = distance(ps[i], ps[i + 1]);

progress = @Time * 1000;
segProgress = 0;
i = 0;
while(segProgress < progress && i < (@numvtx-1))
{
    segProgress += segLens[i];
    i++;
}
progress = fit(progress, max(segProgress - segLens[i-1], 0), segProgress, 0, 1);

for(j = 0; j < i; j++)
    setpointattrib(0, "P", pts[j], lerp(ps[i-1], ps[i], progress));

 

[tamagochy]

18 hours ago, f1480187 said:

If you referring to this topic, solution was for vertical lines. Here is more general way:

// Point wrangle.
float u = (float) @ptnum / (@numpt-1.0);
float time = @Time;

if (u <= time)
{
    @P = primuv(0, "P", 0, time);
}

 

drag_by_u.hipnc

If i need that points have gap between?

[f1480187]

@tamagochy, try offset time by rising value.

float time = @Time + (u * 0.01);