retro.frag

precision mediump float;
varying vec2 v_texcoord;

uniform sampler2D tex;
uniform float time;

void main() {
    vec2 tc = vec2(v_texcoord.x, v_texcoord.y);

    // Distance from the center
    float dx = abs(0.5 - tc.x);
    float dy = abs(0.5 - tc.y);

    // Square it to smooth the edges
    dx *= dx;
    dy *= dy;

    tc.x -= 0.5;
    tc.x *= 1.0 + (dy * 0.03);
    tc.x += 0.5;

    tc.y -= 0.5;
    tc.y *= 1.0 + (dx * 0.03);
    tc.y += 0.5;

    // Add RGB offset for retro color separation effect
    vec2 r_tc = tc + vec2(0.001, 0.0);
    vec2 g_tc = tc;
    vec2 b_tc = tc - vec2(0.001, 0.0);

    vec4 color;
    color.r = texture2D(tex, r_tc).r;
    color.g = texture2D(tex, g_tc).g;
    color.b = texture2D(tex, b_tc).b;
    color.a = 1.0;

    // Add scanlines
    float scanline = sin(tc.y * 1500.0) * 0.05;
    color.rgb += scanline;

    // Add noise
    float noise = (fract(sin(dot(tc.xy + vec2(time), vec2(12.9898, 78.233))) * 43758.5453) - 0.5) * 0.04;
    color.rgb += noise;

    // Apply vignette effect
    float vignette = smoothstep(0.8, 0.2, dx + dy);
    color.rgb *= vignette;

    // Vertical CRT lines with reduced intensity
    float lines = sin((tc.y + time * 0.1) * 40.0) * 0.02;
    color.rgb *= 1.0 - lines;

    // Apply retro orange color transformation
    vec3 retroColor = vec3(
        color.r * 1.2,  // Boost the red channel
        color.g * 1.0,  // Keep the green channel as is
        color.b * 0.8   // Reduce the blue channel
    );
    color.rgb = retroColor;

    // Cutoff
    if (tc.y > 1.0 || tc.x < 0.0 || tc.x > 1.0 || tc.y < 0.0)
        color = vec4(0.0);

    // Apply
    gl_FragColor = color;
}