#version 300 es
precision mediump float;

in vec4 colorLeft;
in vec4 colorRight;
in float edge;
in float midpoint;

out vec4 fragColor;

float curveWithMidpoint(float x, float midpoint) {
	float curveSample = pow(x, midpoint / (1.0 - midpoint));
	float inverseCurveSample = 1.0 - pow(1.0 - x, (1.0 - midpoint) / midpoint);
	return (curveSample + inverseCurveSample) * 0.5;
}

void main() {
	float colorMix = curveWithMidpoint(edge, midpoint);
	fragColor = colorLeft * (1.0 - colorMix) + colorRight * colorMix;
}