#version 130

uniform sampler2D texture;

in vec2 texCoord;
in vec4 color;

out vec4 final;
void main(void) 
{
    vec4 myColor = color;
    final = texture2D(texture, texCoord);
    int P = 1;
    int outline = 0;
    if (final.a == 0.0)
    {
        vec4 px[4] = vec4[](
            texture2D(texture, texCoord+vec2(P, 0)),
            texture2D(texture, texCoord+vec2(0, P)),
            texture2D(texture, texCoord+vec2(-P, 0)),
            texture2D(texture, texCoord+vec2(0, -P))
        );
        
        for(int i = 0; i < 4; ++i)
        {
            if(px[i].a > 0.0)
            {
                myColor = vec4(1.0, 0.0, 0.0, 1.0);
                outline++;
            }
        }

        if(outline == 0)
            discard;
    } 
    final = myColor;
}