//This shader defines two circles - everything inside the inner circle will be darkened, while everything outside the outer circle
//will be full black. Between the inner and outer circle it LERPs from the inner darkness to full black.

light_mode unshaded;

const highp float darknessAlphaInner =  0.6;
const highp float innerCircleRadius = 40.0; //Note: this is in pixels
const highp float outerCircleRadius = 80.0;

void fragment() {
	highp vec2 pixelSize = vec2(1.0/SCREEN_PIXEL_SIZE.x, 1.0/SCREEN_PIXEL_SIZE.y);
    highp vec2 pixelCenter = pixelSize*0.5;
	highp float distance = length(FRAGCOORD.xy - pixelCenter);
	if(distance > outerCircleRadius){
		COLOR = vec4(0.0, 0.0, 0.0, 1.0);
	}
	else if(distance < innerCircleRadius){
		COLOR = vec4(0.0, 0.0, 0.0, darknessAlphaInner);
	}
	else{
		highp float intensity = (distance-innerCircleRadius)/(outerCircleRadius-innerCircleRadius);
		COLOR = vec4(0.0, 0.0, 0.0, (1.0-intensity)*darknessAlphaInner + intensity);
	}
}