shader.vert

const fragShaderSrc = `
#ifdef GL_ES
precision mediump float;
#endif

varying vec2 vTexCoord;
uniform sampler2D u_tex0;
uniform float u_time;

float random(vec2 st) {
    return fract(sin(dot(st.xy, vec2(12.9898,78.233))) * 43758.5453123);
}

void main() {
    float distortion_s = 0.02;
    float glow_s = 0.2;
    float static_s = 0.15;
    float scanline_s = 0.1;
    float fine_noise_s = 0.05;

    if (vTexCoord.x < 0.0 || vTexCoord.x > 1.0 || vTexCoord.y < 0.0 || vTexCoord.y > 1.0) {
        gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
        return;
    }

    float horiz_wobble = sin(vTexCoord.y * 10.0 + u_time * 1.5) * distortion_s;
    vec2 distorted_uv = vTexCoord + vec2(horiz_wobble, 0.0);

    vec3 source_color = texture2D(u_tex0, distorted_uv).rgb;
    float luminance = dot(source_color, vec3(0.299, 0.587, 0.114));
    vec3 color = vec3(luminance);
    
    color = pow(color, vec3(1.4));

    float scanline = sin(vTexCoord.y * 480.0 * 1.5) * scanline_s;
    color -= scanline;

    float tracking_pos = fract(u_time * 0.1);
    float tracking_bar = smoothstep(0.4, 0.0, abs(vTexCoord.y - tracking_pos) * 5.0);
    color -= tracking_bar * static_s * random(vTexCoord + u_time);

    color += (random(vTexCoord) - 0.5) * fine_noise_s;

    float glow = pow(luminance, 4.0) * glow_s;
    color += glow;

    gl_FragColor = vec4(clamp(color, 0.0, 1.0), 1.0);
}
`;