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I am trying to render the world map with elevation data using D3.

For this I use Natural Earth 50m land geojson : https://github.com/martynafford/natural-earth-geojson/tree/master/50m/physical

And Natural Earth elevation raster data : https://www.naturalearthdata.com/downloads/50m-raster-data/50m-shaded-relief/

I am using this tutorial : https://datawanderings.com/2020/08/08/raster-backgrounds/

So I first found the bounds of the geojson :

The axis and variables are the same, but the original data frame is different

I have 4 corners of a rectangle (like this).

I'm using this function to generate a simple gradient bitmap using LinearGradientBrush which I save as a file in the end to use as a wallpaper. But the the problem is the result doesn't look "smooth", it looks rather "choppy" as you can see the colors' lines.

I use the bounds of the screen as the dimensions of the bitmap and increasing the size doesn't improve the quality (I tried 2x and even 4x).

I tried setting the InterpolationMode and SmoothingMode but neither seemed to have an effect on the end result.

Is there a way to fix this issue?

I have an Ionic app using @media (prefers-color-scheme: dark), when I build the ios version using capacitor, it does not respect dark mode. I have tried this node module, looked here, and here, but nothing seems to work. Why does Capacitor not respect dark mode on iOS?

What is should look like.

Variables.css

I want to implement flat shading on OpenGL. I googled it and found this question: How to achieve flat shading with light calculated at centroids?.

I understood the top answer idea and I'm trying to implement it. However, I couldn't figure out how to find the surface normal given the normals of each vertex of the triangle.

Relevant code in vertex shader:

In my very simple case I would like to display the heatmap of the points in the points GeoJSON file but not on the geographic density (lat, long). In the points file each point has a confidence property (a value from 0 to 1), how to display the heatmap on this parameter? weight=points.confidence don't seem to work.

for exemple:

I am currently drawing a grid using a series of triangle strips. I am using this to render a height field, and generating the vertex data completely in the vertex shader without any input buffers just using the vertex and instance indexes. This is all working fine and is very efficient.

However, I now find myself also needing to implement border lines on this grid. The obvious solution here would be something like marching squares. Basically, what I want to achieve is something like this:

The black dots represent the vertices in the grid that are part of some set, and I want to shade the area inside the red line differently than that outside it.

Naïvely, this seems like it would be easy: Add a value to the vertices that is 1 for vertices in the set and 0 for those outside it, and render differently depending on if the interpolated value is above or below 0.5, for instance.

However, because this is rendered as a triangle strip, this does not quite work. In pracitce, since this is rendered as a triangle strip, this ends up looking like this:

So, half the edges work and half end up with ugly square staircases.

I've now been trying to wrack my brain for days whether there is some trick that could be used to generate the vertex values differently or making a more complicated test than >0.5 to get closer to the intended shape without giving up on the nice and simple triangle strips and having to actually generate geometry ahead of time, but I can not think of one.

Has anyone ever dealt with a similar problem? Is there some clever solution I am missing?

I am doing this in Metal, but I don't expect this to depend much on the specific API used.

In the compute shader, I can see that bicubic is an option but only if __HAVE_BICUBIC_FILTERING__ is defined. When I set bicubic as the filtering option, I get a syntax error. Linear or Nearest compile fine. I'm building for metal 2 on MacOS.

Another method would be to define the sampler on the CPU with a sampler descriptor but there is no option for bicubic there either.

The comments in this thread discuss their inability to set bicubic.

I've searched the metal shading language specification, and bicubic is not mentioned there at all. Any help would be appreciated.