Factorio Perspective game.glsl

uniform sampler2D gameview; // "diffuse" texture
uniform sampler2D lightmap;

uniform vec4 nv_color;
uniform float nv_intensity;
uniform vec4 nv_desaturation_params;
uniform vec4 nv_light_params;

uniform float darkness;
uniform float timer;
uniform bool render_darkness;

bool use_nightvision = nv_intensity > 0.0;

void main()
{
  vec2 uv = gl_TexCoord[0].xy;

  vec2 st = uv - vec2(0.5, 0.5);
  st.x /= (1.15 - 0.3 * st.y);
  st.y /= (1.15 - 0.3 * st.y);
  uv = st + vec2(0.5, 0.5);

  vec4 color = texture2D(gameview, uv);
  if (!render_darkness)
  {
    gl_FragColor = color;
    return;
  }

  vec4 light = texture2D(lightmap, uv);

  if (use_nightvision)
  {
    float luminance = dot(color.rgb, vec3(0.299, 0.587, 0.114));
    float lightLuminance = max(light.r, max(light.g, light.b));
    vec3 grayscale = vec3(luminance * nv_intensity); // * nv_color.a * nv_color.rgb;
    float lightIntensity = smoothstep(nv_desaturation_params.x, nv_desaturation_params.y, lightLuminance) * nv_desaturation_params.z + nv_desaturation_params.w;

    color.rgb = mix(grayscale, color.rgb, lightIntensity);
    lightIntensity = smoothstep(nv_light_params.x, nv_light_params.y, lightLuminance) * nv_light_params.z + nv_light_params.w;
    gl_FragColor = vec4(color.rgb * lightIntensity , color.a);
  }
  else
  {
    color.rgb = color.rgb * light.rgb;
    gl_FragColor = vec4(color.rgb, color.a);
  }
}