// GLSL shader code for portraying different environments in a Hollywood movie.
// Effects vary based on a switch statement that takes a country name.
// Includes color desaturation effects that vary based on the country.

uniform float time;
uniform vec2 resolution;
uniform sampler2D texture;

void main() {
  vec2 uv = gl_FragCoord.xy / resolution.xy;
  
  // Switch statement for varying effects based on country name.
  switch(country_name) {
    case "USA":
      // USA-specific effects.
      vec3 color = texture2D(texture, uv).rgb;
      vec3 sepia_tint = vec3(0.9, 0.8, 0.7);
      vec3 final_color = mix(color, sepia_tint, 0.2);
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.2);
      
      // Color desaturation effect.
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.2);
      gl_FragColor = vec4(final_color, 1.0);
      break;
    case "China":
      // China-specific effects.
      vec3 color = texture2D(texture, uv).rgb;
      vec3 red_tint = vec3(1.0, 0.2, 0.1);
      vec3 gray = vec3(0.3, 0.3, 0.3);
      vec3 final_color = mix(color, gray, 0.5);
      final_color = mix(final_color, red_tint, 0.2);
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.3);
      
      // Color desaturation effect.
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.3);
      gl_FragColor = vec4(final_color, 1.0);
      break;
    case "Russia":
      // Russia-specific effects.
      vec3 color = texture2D(texture, uv).rgb;
      vec3 gray = vec3(0.3, 0.3, 0.3);
      vec3 cold_tint = vec3(0.7, 0.8, 0.9);
      vec3 final_color = mix(color, gray, 0.4);
      final_color = mix(final_color, cold_tint, 0.2);
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.4);
      
      // Color desaturation effect.
      final_color = mix(final_color, vec3(dot(final_color, vec3(0.2126, 0.7152, 0.0722))), 0.4);
      gl_FragColor = vec4(final_color, 1.0);
      break;
    default:
      // Default effects.
      gl_FragColor = texture2D(texture, uv);
      break;
  }
}