#version 330

in vec2 fragTexCoord;
in vec4 fragColor;

out vec4 finalColor;

uniform sampler2D texture0;
uniform vec4 colDiffuse;

// Adjust these values to tweak the aesthetic:
const float SCANLINE_INTENSITY = 0.25; // Lower value = softer lines (0.08 to 0.20)
const float BLOOM_AMOUNT       = 0.10; // Slight phosphor bleed/glow
const float CRT_CURVATURE      = 0.03; // Subtle screen bulge (0.0 = flat)

void main() {
    // 1. Subtle screen curvature distortion
    vec2 uv = fragTexCoord;
    vec2 dc = abs(0.5 - uv);
    uv.x += uv.x * (dc.y * dc.y) * CRT_CURVATURE;
    uv.y += uv.y * (dc.x * dc.x) * CRT_CURVATURE;

    // Discard pixels outside the curved screen bounds
    if (uv.x < 0.0 || uv.x > 1.0 || uv.y < 0.0 || uv.y > 1.0) {
        finalColor = vec4(0.0, 0.0, 0.0, 1.0);
        return;
    }

    // 2. Sample pixel with slight horizontal blur (Phosphor bleed)
    vec4 col = texture(texture0, uv);
    vec4 col_left  = texture(texture0, uv - vec2(0.0008, 0.0));
    vec4 col_right = texture(texture0, uv + vec2(0.0008, 0.0));
    col.rgb = mix(col.rgb, (col_left.rgb + col_right.rgb) * 0.5, BLOOM_AMOUNT);

    // 3. Gaussian scanline profile matching 360 vertical lines
    float scanline = sin(uv.y * 360.0 * 3.14159);
    // Smooth power curve prevents harsh pitch-black cutoffs
    float scanline_factor = pow(0.5 + 0.5 * scanline, 1.8); 

    // Apply scanlines smoothly
    col.rgb *= mix(1.0 - SCANLINE_INTENSITY, 1.0, scanline_factor);

    // 4. Subtle corner vignette
    float vig = (16.0 * uv.x * uv.y * (1.0 - uv.x) * (1.0 - uv.y));
    col.rgb *= pow(vig, 0.05);

    finalColor = col * colDiffuse * fragColor;
}