For each country:
a grid is generated for each year. the total fragility score is mapped to the angles of the flow field. the flow field is also distorted by perlin noise, the parameters of which are determined based on the total fragility score. each crack starts at the centre of the canvas and propagates outwards as frames go on. colours are randomly selected among the country's flag colours. the colour blend mode is set to "multiply". so, if a country's total fragility score is high and it has high variations during many years then there will be more overlapping cracks ultimately creating black lines. also the propagating cracks will have a greater chance to escape the main grid area if a country has very low total fragility score that has been well maintained and remained stable during many years.