#ifdef VERT

attribute vec2 position;
attribute vec2 texCoord;

varying vec2 vTexCoord;

void main() {
  gl_Position = vec4(position, 0.0, 1.0);
  vTexCoord = texCoord;
}

#endif

#ifdef FRAG

varying vec2 vTexCoord;

uniform sampler2D image;
uniform vec2 imageSize;
uniform float amount;

vec4 gauss(sampler2D image, vec2 texel, float amount) {
  vec4 color = vec4(0.0);
  color += 1.0/16.0 * texture2D(image, vTexCoord + vec2(0.0, texel.y * -2.0 * amount));
  color += 4.0/16.0 * texture2D(image, vTexCoord + vec2(0.0, texel.y * -1.0 * amount));
  color += 6.0/16.0 * texture2D(image, vTexCoord + vec2(0.0, texel.y *  0.0 * amount));
  color += 4.0/16.0 * texture2D(image, vTexCoord + vec2(0.0, texel.y *  1.0 * amount));
  color += 1.0/16.0 * texture2D(image, vTexCoord + vec2(0.0, texel.y *  2.0 * amount));
  return color;
}

void main() {
  vec2 texel = vec2(1.0 / imageSize.x, 1.0 / imageSize.y);

  vec4 color = gauss(image, texel, amount);
  gl_FragColor = color;
}

#endif