input View {
  mat4 mvp,
  mat4 proj,
  mat4 proj_inverse,
  mat4 view,
  mat4 world, //geometry.world atm
  float2 fov, //fov.x, fov.y
  float2 resolution,
  float4 target_region,
  float4 target_region_size
}

input Font {
  image2D pages[8]
}

stage vertex vert(
    input { View view },
    vertex in { #0 float4 pos, #1 float4 color, #2 float2 uv },
    fragment out { float4 color, float2 uv, float page })
{
    out.color = in.color;
    out.uv = in.uv;
    out.page = in.pos.w;
    stage.pos = input.view.mvp * float4(in.pos.xyz, 1.0);
}

stage fragment frag(
    input { Font font },
    fragment in { float4 color, float2 uv, float page })
{
  int page = int(in.page);
  float4 msdf_sample = texture(input.font.pages[0], in.uv.xy);
  if(page == 1) { msdf_sample = texture(input.font.pages[1], in.uv.xy); }
  if(page == 2) { msdf_sample = texture(input.font.pages[2], in.uv.xy); }
  if(page == 3) { msdf_sample = texture(input.font.pages[3], in.uv.xy); }
  if(page == 4) { msdf_sample = texture(input.font.pages[4], in.uv.xy); }
  if(page == 5) { msdf_sample = texture(input.font.pages[5], in.uv.xy); }
  if(page == 6) { msdf_sample = texture(input.font.pages[6], in.uv.xy); }
  if(page == 7) { msdf_sample = texture(input.font.pages[7], in.uv.xy); }

  float r = msdf_sample.r;
  float g = msdf_sample.g;
  float b = msdf_sample.b;
  float median = max(min(r, g), min(max(r, g), b));
  float opacity = float(median > 0.5);

  stage.color[0] = float4(in.color.rgb, in.color.a * opacity);
}