module Render.Font.EvanwSdf.Code
  ( vert
  , frag
  ) where

import RIO

import Render.Code (Code, glsl)
import Render.DescSets.Set0.Code (set0binding0, set0binding1, set0binding2)

vert :: Code
vert = fromString
  [glsl|
    #version 450

    ${set0binding0}

    layout(location = 0) in  vec4 iVert;
    layout(location = 1) in  vec4 iFrag;
    layout(location = 2) in  vec4 iColor;
    layout(location = 3) in  vec4 iOutlineColor;
    layout(location = 4) in ivec2 iTextureIds;
    layout(location = 5) in  vec2 iSdf;

    layout(location = 0)      out  vec2 fTexCoord;
    layout(location = 1) flat out  vec4 fColor;
    layout(location = 2) flat out  vec4 fOutlineColor;
    layout(location = 3) flat out ivec2 fTextureIds;
    layout(location = 4) flat out  vec2 fSdf;

    vec2 positions[6] = vec2[](
      vec2(-0.5, 0.5),
      vec2(0.5, 0.5),
      vec2(-0.5, -0.5),

      vec2(0.5, -0.5),
      vec2(-0.5, -0.5),
      vec2(0.5, 0.5)
    );

    vec2 texCoords[6] = vec2[](
      vec2(0.0, 0.0),
      vec2(1.0, 0.0),
      vec2(0.0, 1.0),

      vec2(1.0, 1.0),
      vec2(0.0, 1.0),
      vec2(1.0, 0.0)
    );

    void main() {
      vec2 pos = positions[gl_VertexIndex];

      gl_Position
        = scene.projection
        * scene.view
      // TODO: * iModel
        * vec4(iVert.xy + pos * iVert.zw, 0, 1.0);

      vec2 uv = texCoords[gl_VertexIndex];
      fTexCoord = iFrag.xy + uv * iFrag.zw;

      fColor = iColor;
      fOutlineColor = iOutlineColor;
      fTextureIds = iTextureIds;
      fSdf = iSdf;
    }
  |]

frag :: Code
frag = fromString
  [glsl|
    #version 450
    #extension GL_EXT_nonuniform_qualifier : enable

    ${set0binding1}
    ${set0binding2}

    layout(location = 0)      in  vec2 fTexCoord;
    layout(location = 1) flat in  vec4 fColor;
    layout(location = 2) flat in  vec4 fOutlineColor;
    layout(location = 3) flat in ivec2 fTextureIds;
    layout(location = 4) flat in  vec2 fSdf;

    layout(location = 0) out vec4 outColor;

    void main() {
      float sdf = texture(
        sampler2D(
          textures[nonuniformEXT(fTextureIds.t)],
          samplers[nonuniformEXT(fTextureIds.s)]
        ),
        fTexCoord
      ).r;

      float smoothing    = fSdf[0];
      float outlineWidth = fSdf[1];

      float outerEdgeCenter = 0.5 - outlineWidth;

      float alpha = smoothstep(
        outerEdgeCenter - smoothing,
        outerEdgeCenter + smoothing,
        sdf
      );
      float border = smoothstep(
        0.5 - smoothing,
        0.5 + smoothing,
        sdf
      );
      outColor = mix(fOutlineColor, fColor, border);
      outColor *= alpha;
    }
  |]