AreaChart renderer bug

[Doge815]

The area chart renderer creates unnecessary and wrong triangles.

use egui_plotter::Chart;
use eframe::egui::{self};
use plotters::prelude::*;

 fn main() {
    test_chart();
    let options = eframe::NativeOptions {
        initial_window_size: Some(egui::vec2(320.0, 240.0)),
        ..Default::default()
    };
    let _ = eframe::run_native("Test", options, Box::new(|_cc| Box::<App>::new(App::default())));
}

struct App {
    chart: Chart
}

impl Default for App {
    fn default() -> Self {
        Self {
            chart: create_chart()}
    }
}


impl eframe::App for App {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        ctx.request_repaint();
        egui::CentralPanel::default().show(ctx, |ui| {
            self.chart.draw(ui);
        });
        }
    }
    
fn create_chart() -> Chart {
    Chart::new()
        .builder_cb(Box::new(|area, _t, _| {
                let mut chart = ChartBuilder::on(area)
                    .set_label_area_size(LabelAreaPosition::Left, 40)
                    .set_label_area_size(LabelAreaPosition::Bottom, 40)
                    .margin(5)
                    .build_cartesian_2d(0..10, 0..50)
                    .unwrap();

                chart.configure_mesh().draw().unwrap();

                let data = [25, 37, 15, 32, 45, 33, 32, 10, 29, 0, 21];
                chart
                    .draw_series(
                        AreaSeries::new((0..).zip(data.iter().enumerate().map(|x| (*x.1 as i32))),
                        0, &RED.mix(0.2)).border_style(&RED)
                    )
                    .unwrap();
    }))

}

pub fn test_chart() {
    let root_area = BitMapBackend::new("image.png", (600, 400))
    .into_drawing_area();
    root_area.fill(&WHITE).unwrap();

                let mut chart = ChartBuilder::on(&root_area)
                    .set_label_area_size(LabelAreaPosition::Left, 40)
                    .set_label_area_size(LabelAreaPosition::Bottom, 40)
                    .margin(5)
                    .build_cartesian_2d(0..10, 0..50)
                    .unwrap();

                chart.configure_mesh().draw().unwrap();

                let data = [25, 37, 15, 32, 45, 33, 32, 10, 29, 0, 21];
                chart
                    .draw_series(
                        AreaSeries::new((0..).zip(data.iter().enumerate().map(|x| (*x.1 as i32))),
                        0, &RED.mix(0.2)).border_style(&RED)
                    )
                    .unwrap();
}

The output of egui-plotter is:

The output of plotters with the BitmapBackend is:

[Gip-Gip]

Investigating now, sorry for the delay

[Gip-Gip]

Looks like some issue with egui's tesselator, or at least is my guess. Will try to work around this however