Simple Pie Chart

Displays a pie chart based on an array of colors and percentages.

The last color’s percentage is the remainder after the other four are added. Percentages adding to more than 1 may be unpredictable. 

Supports a mild blur effect to avoid hard edges in color and transparency.

I had thought I wanted little pie charts in my game. Turns out I don’t need it, but maybe someone else will find a use.

If changing the number of colors, need to manually change the array sizes, either due to a limitation of godot’s shader language or a limitation of my ability to use it.

Shader code
shader_type canvas_item;

const int num_colors = 5;
const int num_shares = num_colors - 1;
uniform vec4 colors[5] : source_color;
uniform float shares[4];  // The last color gets the remainder
uniform float relative_size : hint_range(0.0, 1.0, 0.1) = 1.;
uniform float blur_strength : hint_range(0., .1, .005) = .01;

void fragment() {
	float angle = (atan(.5-UV.y, UV.x-.5) + PI)/(2.*PI);
	float r = length(UV-vec2(.5));
	float tot_shares = 0.;
	
	COLOR = mix(colors[num_colors - 1],colors[0], smoothstep(blur_strength, .0, 1. - angle));
	for (int i = 0; i < num_colors-1; i++) {
		tot_shares += shares[i];
		if (angle  < tot_shares) {
			COLOR = mix(colors[i],colors[i+1], smoothstep(blur_strength, .0, abs(angle-tot_shares)));
			break;
		}
	}
	COLOR.a = min(COLOR.a, smoothstep(0, blur_strength*2., relative_size*.5 - r));
}
The shader code and all code snippets in this post are under CC0 license and can be used freely without the author's permission. Images and videos, and assets depicted in those, do not fall under this license. For more info, see our License terms.

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