question about feature script sketch merge and constrain when using circular pattern

Jeffrey42

Hi, I have two questions about my 2D sketches project at school.
first, when I use the circular pattern, the sketch will not fully constrain. I try to use skconstrain tool but realize that I need to skslove the sketch to be able to use the circular pattern tool. I do not know how to use the skconstrain when the sketch was already solved.

the second question is also about the constraint. Since I sketch my circles and arcs in different sketches so they do not recognize each other, which make perfect sense. However, Is there a way to merge different sketches?




using a circular pattern with multiple sketches
https://cad.onshape.com/documents/13fd38394d33485d50d1541d/w/7bb55977ab2fa287378daae6/e/afef66410945473a7c0073c3

end up hardcoding everything in the second version on below works but not pretty:
https://cad.onshape.com/documents/7bd52314a96f9a14b24e8ca8/w/290640dd845c1e9488e4008d/e/4a2a3650ac6f9bad46b17163

Thank you in advance

paul_chastell

The problem may be that circularPattern is a feature operation. If your goal is to put all the geometry in the same sketch I would suggest making all the geometry in the same sketch to begin with, which is what the second document appears to do. You don't need to add any constraints at all if you make the geometry in the correct place. However, if you want the sketch to do the work for you, and reposition geometry to meet the constraints of the pattern, then you will. Doing it yourself, using loops rather than coding each one individually would make for more concise code with fewer bugs, e.g. draw_lit_cir could be rewritten with a loop, a bit of math, and only one call to skCircle. 

Note that adding pattern constraints probably won't help you anyway because you still need to create all the geometry and you probably need to create it close to where it will eventually be so that Onshape has a chance of solving. Were I doing this I would not add constraints, I would just use math and loops.

paul_chastell

And I've added a simple example of what I mean here: https://cad.onshape.com/documents/8e940365ff5576f2d5947b66/w/87fa8e9e372ccba0ab8f9bc0/e/943f06a64756586adae6da37

annotation { "Feature Type Name" : "Patterned sketch" }
export const patterned = defineFeature(function(context is Context, id is Id, definition is map)
    precondition
    {
        annotation { "Name" : "Count" }
        isInteger(definition.count, POSITIVE_COUNT_BOUNDS);
    }
    {
        // Make the sketch
        const sketch = newSketchOnPlane(context, id + "sketch", {
                    "sketchPlane" : plane(vector(0, 0, 0) * meter, vector(0, 0, 1))
                });

        // Define the position of the geometry for the 'seed' position
        const mm = millimeter;
        const start = vector(100, 10, 0) * mm;
        const mid = vector(130, 0, 0) * mm;
        const end = vector(100, -10, 0) * mm;

        const axis = line(vector(0, 0, 0) * meter, vector(0, 0, 1));
        const full = PI * 2 * radian;

        // Loop through the required number of instances, transform the points and create the geometry
         for (var i = 0; i < definition.count; i += 1)
        {
            const lineId = "line" ~ i;
            const arcId = "arc" ~ i;

            const rotation = rotationAround(axis, (i / definition.count) * full);
            const start3d = rotation * start;
            const mid3d = rotation * mid;
            const end3d = rotation * end;

            const start2d = vector(start3d[0], start3d[1]);
            const mid2d = vector(mid3d[0], mid3d[1]);
            const end2d = vector(end3d[0], end3d[1]);
            
            skLineSegment(sketch, lineId, {
                        "start" : start2d,
                        "end" : end2d 
                    });

            skArc(sketch, arcId, {
                        "start" : start2d,
                        "mid" : mid2d,
                        "end" : end2d
                    });
        }
        skSolve(sketch);
    });

NeilCooke

Hi @jeffrey_chaing I’ve not heard of projects requiring FeatureScript before? What is the project end goal? It is likely you can save yourself a lot of effort just using the available built-in tools. 

Jeffrey42

Hi, @NeilCooke our school wants us to draw sketches from FeatureScript. We basically learning the FeatureScript tools, so we could use it on generative designed later on. We did draw it using the built-in tools as well. Just want to know is there ways to actually merge sketches or constrain a circular pattern in the FeatureScript?

Thank you for the reply

paul_chastell

The problem may be that circularPattern is a feature operation. If your goal is to put all the geometry in the same sketch I would suggest making all the geometry in the same sketch to begin with, which is what the second document appears to do. You don't need to add any constraints at all if you make the geometry in the correct place. However, if you want the sketch to do the work for you, and reposition geometry to meet the constraints of the pattern, then you will. Doing it yourself, using loops rather than coding each one individually would make for more concise code with fewer bugs, e.g. draw_lit_cir could be rewritten with a loop, a bit of math, and only one call to skCircle. 

Note that adding pattern constraints probably won't help you anyway because you still need to create all the geometry and you probably need to create it close to where it will eventually be so that Onshape has a chance of solving. Were I doing this I would not add constraints, I would just use math and loops.

Jeffrey42

Hi, @paul_chastell. Thank you for the clarification.

paul_chastell

And I've added a simple example of what I mean here: https://cad.onshape.com/documents/8e940365ff5576f2d5947b66/w/87fa8e9e372ccba0ab8f9bc0/e/943f06a64756586adae6da37

annotation { "Feature Type Name" : "Patterned sketch" }
export const patterned = defineFeature(function(context is Context, id is Id, definition is map)
    precondition
    {
        annotation { "Name" : "Count" }
        isInteger(definition.count, POSITIVE_COUNT_BOUNDS);
    }
    {
        // Make the sketch
        const sketch = newSketchOnPlane(context, id + "sketch", {
                    "sketchPlane" : plane(vector(0, 0, 0) * meter, vector(0, 0, 1))
                });

        // Define the position of the geometry for the 'seed' position
        const mm = millimeter;
        const start = vector(100, 10, 0) * mm;
        const mid = vector(130, 0, 0) * mm;
        const end = vector(100, -10, 0) * mm;

        const axis = line(vector(0, 0, 0) * meter, vector(0, 0, 1));
        const full = PI * 2 * radian;

        // Loop through the required number of instances, transform the points and create the geometry
         for (var i = 0; i < definition.count; i += 1)
        {
            const lineId = "line" ~ i;
            const arcId = "arc" ~ i;

            const rotation = rotationAround(axis, (i / definition.count) * full);
            const start3d = rotation * start;
            const mid3d = rotation * mid;
            const end3d = rotation * end;

            const start2d = vector(start3d[0], start3d[1]);
            const mid2d = vector(mid3d[0], mid3d[1]);
            const end2d = vector(end3d[0], end3d[1]);
            
            skLineSegment(sketch, lineId, {
                        "start" : start2d,
                        "end" : end2d 
                    });

            skArc(sketch, arcId, {
                        "start" : start2d,
                        "mid" : mid2d,
                        "end" : end2d
                    });
        }
        skSolve(sketch);
    });

Jeffrey42

Thank you  @paul_chastell. The rotationAround function is really helpful!! 

Jeffrey42

Hello, @paul_chastell. Thank you for helping me with my school projects. I was able to make it work!
If you have want to take a look below is my github. We able to play with the 3D as well
github: https://github.com/JCTGY/2D_FeatureScript

Onshape: https://cad.onshape.com/documents/7bd52314a96f9a14b24e8ca8/w/290640dd845c1e9488e4008d/e/a40c1ed49153c80a4acac5b6

paul_chastell

Excellent! Happy to help.