Alternative of matplotlib.pcolormesh?

[Ionizing]

Recently I came up with an idea that using egui to simulate STM images, which is based on like matplotlib.pcolormesh, and the example is in the following:

The problem is that, though egui provides ColorImage to show the 2D data, the STM may contains shape other than rectangles (such as parallelogram). This feature of STM image requires egui to show each point with corresponding coordinates.
Therefore, the data structure should consist of two parts and be designed as below:

• 2D height/current data ([[f64; n]; m])
• the coordinates of each point corresponding to the 2D data ([[[f64; 2]; n]; m])
• a colormap that transform height/current data to Color32

Then apply the function and obtain the image.

My question is which function should I use to do the job or to implement an alternative to pcolormesh?
I browsed the documentation and found Mesh::colored_vertex may be an appropriate one but failed to build a minimal working example.

Could you please give some advice?
Much appreciation in advance.

[Ionizing]

It seems I need to implement a method to convert the coordinates to vertices, then add the corresponding triangles to painter. (according to the implementation of add_rect_with_uv)

The next issue is that this naive implementation would show a coarse image and I have to perform the interpolation by myself.

[Ionizing]

I found that Mesh will do the interpolation by default, which would save a lot of effort.

use eframe::{
    App,
    egui::{
        CentralPanel,
        Mesh,
        Pos2,
        Vec2,
        Color32,
        Shape,
        Rect,
    },
    run_native,
    NativeOptions,
};


#[derive(Default)]
struct MyImage;

impl MyImage {
    fn ui(&mut self, ui: &mut egui::Ui) {
        let pos = Pos2::new(5.0, 8.0);
        let clr = Color32::RED;
        let mut mesh = Mesh::default();

        let idx = mesh.vertices.len() as u32;
        mesh.colored_vertex(Pos2::new(200.0,                    0.0), Color32::RED);
        mesh.colored_vertex(Pos2::new(  0.0, 200.0 * 3.0_f32.sqrt()), Color32::GREEN);
        mesh.colored_vertex(Pos2::new(400.0, 200.0 * 3.0_f32.sqrt()), Color32::BLUE);
        mesh.add_triangle(idx + 0, idx + 1, idx + 2);

        ui.painter().add(Shape::mesh(mesh));
    }
}


impl App for MyImage {
    fn update(&mut self, ctx: &eframe::egui::Context, _: &mut eframe::Frame) {
        CentralPanel::default().show(ctx, |ui| {
            self.ui(ui);
        });
    }
}


fn main() {
    let app = MyImage::default();
    let win_option = NativeOptions::default();
    run_native(
        "Mesh",
        win_option,
        Box::new(|_| Box::new(app))
    ).unwrap();
}