#ifdef GL_ES
    precision mediump float;
#endif

varying vec4 v_color;
varying vec2 v_texCoords;

uniform float smew;
uniform sampler2D u_texture;

vec2 distort(vec2 p) {
    float x = sin( 25.0*p.y + 30.0*p.x + 6.28) * 0.01;
    float y = sin( 25.0*p.y + 30.0*p.x + 6.28) * 0.01;
    return vec2(p.x + x, p.y + y);
}

void main()
{
    float width = 0.2;
    vec4 color = v_color * texture2D(u_texture, distort(v_texCoords));
    if ((v_texCoords.x < v_texCoords.y + smew + width) && (v_texCoords.x > v_texCoords.y + smew - width)) {
        color *= 2.0;
    }
    gl_FragColor = color;
}