#version 300 es
precision mediump float;

in vec2 texCoord;

uniform sampler2D colorTexture;
uniform float inset;

out vec4 fragColor;

void main() {
	vec4 color = texelFetch(colorTexture, ivec2(texCoord), 0);
	vec2 changePerTexel = fwidth(texCoord);
	vec2 fraction = fract(texCoord);
	vec2 colorMixesMin = min(vec2(inset, inset), fraction / changePerTexel);
	vec2 colorMixesMax = min(vec2(inset, inset), (1.0 - fraction) / changePerTexel);
	vec2 colorMixes = min(colorMixesMin, colorMixesMax);
	
	float colorMix = 0.5 + smoothstep(inset - 0.125, inset - 0.0625, min(colorMixes.x, colorMixes.y)) * 0.5;
	fragColor = color * colorMix;
}