#version 300 es

precision mediump float;

in vec4 color;
in vec2 texCoord;
in float textureIndex;

uniform sampler2D textures[8];
uniform float threshold;
uniform float smoothRange;

out vec4 fragColor;

void main() {
	float sample = 0.0;
	float smoothMin = threshold - smoothRange * 0.5;
	float smoothMax = smoothMin + smoothRange;
	sample += smoothstep(smoothMin, smoothMax, texture(textures[0], texCoord).r) * (step(-0.5, textureIndex) - step(0.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[1], texCoord).r) * (step(0.5, textureIndex) - step(1.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[2], texCoord).r) * (step(1.5, textureIndex) - step(2.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[3], texCoord).r) * (step(2.5, textureIndex) - step(3.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[4], texCoord).r) * (step(3.5, textureIndex) - step(4.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[5], texCoord).r) * (step(4.5, textureIndex) - step(5.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[6], texCoord).r) * (step(5.5, textureIndex) - step(6.5, textureIndex));
	sample += smoothstep(smoothMin, smoothMax, texture(textures[7], texCoord).r) * (step(6.5, textureIndex) - step(7.5, textureIndex));
	fragColor = vec4(max(1.0, sample));
	fragColor *= color;
}