Creating consistent lines in a path

eric_ma454

Currently, I have a query of lines from input, and I wish to create a path, and then analyze them as lines in order. Currently, I have:

var path = constructPath(context, definition.edges);

var nLines = size(path.edges);

var tangentLines = evPathTangentLines(context, path, range(0,1,nLines));

I am accessing the lines through tangentLines.tangentLines[index]. However, when debugging the lines in a part studio with a basic sketch, upon adding more lines (starting around 4-5 lines), some lines seem to get skipped over, while others have multiple debug vectors. Is there a consistent way to get an array/map of all distinct lines in order of a path, from one end to another?

Best,
Eric Ma

konstantin_shiriazdanov

if your path consists of linear edges only, and you need a line of each edge in the path order then you need to iterate through the edges and evaluate the line of each

for (edge in path.edges)

{

var L = evLine(... edge);

}

Jake_Rosenfeld

@eric_ma454

For some context on why this is happening, evPathTangentLines divides up the path by the total length.  So if some of the lines are long and some are short, you can imagine that an equal division based on length may not actually hit all of the lines.  @konstantin_shiriazdanov 's solution will provide you with what you need, but you may also have to flip the direction if you need the edge directions to be constantly "forward" in the path:

for (var i = 0; i < size(path.edges); i += 1)
{
    var edgeLine = evLine(context, { "edge" : path.edges[i] });
    if (path.flipped[i])
    {
        edgeLine.direction *= -1;
    }
}

If your edges are not guaranteed to be linear, you may want to replace evLine with

evEdgeTangentLine(context, { "edge" : path.edges[i], "parameter" : 0.5 });

to get the tangent line at the middle of the edge.

Jake_Rosenfeld

@eric_ma454

Since tangentLines is an array of all the lines you've processed so far, you need:

tangentLines[i].direction *= -1;

not

tangentLines.direction *= -1;

MBartlett21

Could you provide a link?

konstantin_shiriazdanov

if your path consists of linear edges only, and you need a line of each edge in the path order then you need to iterate through the edges and evaluate the line of each

for (edge in path.edges)

{

var L = evLine(... edge);

}

Jake_Rosenfeld

@eric_ma454

For some context on why this is happening, evPathTangentLines divides up the path by the total length.  So if some of the lines are long and some are short, you can imagine that an equal division based on length may not actually hit all of the lines.  @konstantin_shiriazdanov 's solution will provide you with what you need, but you may also have to flip the direction if you need the edge directions to be constantly "forward" in the path:

for (var i = 0; i < size(path.edges); i += 1)
{
    var edgeLine = evLine(context, { "edge" : path.edges[i] });
    if (path.flipped[i])
    {
        edgeLine.direction *= -1;
    }
}

If your edges are not guaranteed to be linear, you may want to replace evLine with

evEdgeTangentLine(context, { "edge" : path.edges[i], "parameter" : 0.5 });

to get the tangent line at the middle of the edge.

eric_ma454

@Jake_Rosenfeld
Thank you for the answer, this method worked very well. However, it seems that if I select lines in the precondition out of order of a path, it throws an error. Is there any way to fix this?
https://cad.onshape.com/documents/b3341e1949df657d55730d83/w/10c62cb1d20fa73f85db9b2f/e/39b17b46a08eb0173e635858

Jake_Rosenfeld

@eric_ma454

Since tangentLines is an array of all the lines you've processed so far, you need:

tangentLines[i].direction *= -1;

not

tangentLines.direction *= -1;