entry

glow.frag.glsl

uniform sampler2D alpha;
uniform sampler2D textureRgba;
uniform int mode;
uniform vec4 color;
uniform vec4 multiplierColor;

varying vec2 texCoord;

uniform int width;
uniform int height;
uniform float outlineStrength;
uniform float radius;

vec4 sample2D(vec2 texCoord)
{
  vec4 rgb = texture2D(textureRgba, texCoord);
  vec4 a = texture2D(alpha, texCoord);
  vec4 clr = multiplierColor * vec4(rgb.xyz, a.r * float(1 - mode) + rgb.a * float(mode));

  return clr;
}

vec4 outline(vec2 texCoord)
{
    float t = 0.0;
    float w = outlineStrength/float(width);
    float h = outlineStrength/float(height);
    float sq = 1.0 / sqrt(2.0);

    t = sample2D(texCoord).a;
    t = max(t, sample2D(texCoord + vec2(0.0, - h)).a);
    t = max(t, sample2D(texCoord + vec2(0.0, h)).a);
    t = max(t, sample2D(texCoord + vec2(-w, 0.0)).a);
    t = max(t, sample2D(texCoord + vec2(w, 0.0)).a);
    t = max(t, sample2D(texCoord + vec2(-w * sq, - h * sq)).a);
    t = max(t, sample2D(texCoord + vec2(w * sq, - h * sq)).a);
    t = max(t, sample2D(texCoord + vec2(w * sq, h * sq)).a);
    t = max(t, sample2D(texCoord + vec2(w * sq, h * sq)).a);

    return vec4(color.xyz, t * color.a);
}

vec4 blur(vec2 texCoord)
{
  float dx = radius / float(width);
  float dy = radius / float(height);
  float sq = 1.0 / sqrt(2.0);

  vec4 c = outline(texCoord);

  c += outline(texCoord + vec2( dx,  0.0));
  c += outline(texCoord + vec2(-dx,  0.0));
  c += outline(texCoord + vec2( 0.0, -dy));
  c += outline(texCoord + vec2( 0.0,  dy));
  c += outline(texCoord + vec2(-dx * sq,  dy * sq));
  c += outline(texCoord + vec2( dx * sq, -dy * sq));
  c += outline(texCoord + vec2( dx * sq,  dy * sq));
  c += outline(texCoord + vec2(-dx * sq, -dy * sq));

  return vec4(c.r * 0.125, c.g * 0.125, c.b * 0.125, c.a * 0.125);
}



void main()
{
    vec4 clr = sample2D(texCoord);
    vec4 blured = blur(texCoord);
    vec4 r = vec4(0.0, 0.0, 0.0, 0.0);

    if (clr.a < 0.5)
      r = blured;
    else
      r = clr;

    gl_FragColor = r;
}