#version 300 es
precision highp float;

in vec2 v_texcoord;
uniform sampler2D tex;
out vec4 fragColor;

void main() {
    float offset = 0.004;

    float r = texture(tex, v_texcoord + vec2( offset, 0.0)).r;
    float g = texture(tex, v_texcoord                   ).g;
    float b = texture(tex, v_texcoord - vec2( offset, 0.0)).b;
    float a = texture(tex, v_texcoord).a;

    fragColor = vec4(r, g, b, a);
}