Flickering of lines while rendering

[ComradeMashkov]

I am experiencing an issue in my program where lines appear to flicker or jitter when rendered. I have attached a gif that demonstrates the problem. Could you please help investigate what might be causing this?

gif

[gwaldron]

Your link gives a 404. Can you try again?

[ComradeMashkov]

Sorry, my fault.

gif

[gwaldron]

Thanks. This is happening due to floating-point precision loss when using ECEF coordinates in the geometry.
We are working on another API call Line (et al) that lets you push the verts with geopoints -- this will eliminate the issue.
Stay tuned...this will be fixed soon.

[gwaldron]

I pushed a commit that should resolve this issue. The API has changed though, so please refer to Demo_Line.h to see how it's done.
You need to call setReferencePoint and then use the returned SRSOperation to submit your points.
Commit 9fdb53e

[ComradeMashkov]

Thanks for your fast reply! However, it didn't resolve my problem. My rendered lines are still flickering during camera rotation & movement. I don't get what is the root of this problem... Maybe I'm doing something wrong?

    // First, create the line entity
    entt::entity lineEntity = entt::null;

    lineEntity = app.entities.create();

    rocky::Line& line = app.entities.emplace<rocky::Line>(lineEntity);

    // Set a reference point. This should be near your geometry, and will
    // act as an anchor point for localizing geometry.
    // Use the returned SRSOperation to transform points for use in your line.
    rocky::GeoPoint refPoint(rocky::SRS::WGS84, 50.103129, 26.327247);
    auto lineXform = line.setReferencePoint(refPoint);
    std::vector<glm::dvec3> points;

    const std::string path_to_coords = native_dir + "data\\coords\\global_trajectories2.csv";
    const std::vector<double> latitude = utils::GetPoints(path_to_coords, "lat", id, 10);
    const std::vector<double> longitude = utils::GetPoints(path_to_coords, "lon", id, 10);
    const std::vector<double> altitude = utils::GetPoints(path_to_coords, "z", id, 10);

    for (int i = 0; i < latitude.size(); ++i)
    {
        glm::dvec3 point; 
        if (lineXform.transform(glm::dvec3(longitude[i], latitude[i], altitude[i]), point))
        {
            points.emplace_back(point);
        }
    }
    
    line.push(points.begin(), points.end());

    line.style = rocky::LineStyle();
    line.style->color = color;
    line.style->width = 2.0f;
    line.style->stipple_pattern = 0xffff;
    line.style->stipple_factor = 1;
    line.write_depth = true;

[gwaldron]

Hmm, and you are sure the reference point is reasonably close to your data points?
Maybe you can upload a small data sample for us to test?

[ComradeMashkov]

Yes, I've double-checked it, but I can be wrong ofc. Here is the data for plotting points for one line.
test.csv

[gwaldron]

Thanks, that helps. Try a new pull - should be better.

[ComradeMashkov]

Thank you! That helped a lot, it solved an issue. Works great!

result

[gwaldron]

Update:
I had to change the API again, so there's a new answer to this question. Such is life with a pre-1.0 SDK :)
We made these changes while refining the ECS architecture.

The old approach (above) included calling setReferencePoint and using the returned SRSOperation.

The new approach is similar but simpler:

line.referencePoint = GeoPoint(...);

Then, just add a vector of points, expressed in the SRS of the reference point (e.g., lon, lat, alt).

[ComradeMashkov]

Thanks! Working as good as always.