gsk/ngl/resources/inset_shadow.glsl


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// VERTEX_SHADER:
// inset_shadow.glsl

uniform float u_spread;
uniform vec2 u_offset;
uniform vec4[3] u_outline_rect;

_OUT_ vec4 final_color;
_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;

void main() {
  gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);

  final_color = gsk_premultiply(aColor) * u_alpha;

  GskRoundedRect outside = gsk_create_rect(u_outline_rect);
  GskRoundedRect inside = gsk_rounded_rect_shrink(outside, vec4(u_spread));

  gsk_rounded_rect_offset(inside, u_offset);

  gsk_rounded_rect_transform(outside, u_modelview);
  gsk_rounded_rect_transform(inside, u_modelview);

  gsk_rounded_rect_encode(outside, transformed_outside_outline);
  gsk_rounded_rect_encode(inside, transformed_inside_outline);
}

// FRAGMENT_SHADER:
// inset_shadow.glsl

_IN_ vec4 final_color;
_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;

void main() {
  vec2 frag = gsk_get_frag_coord();
  float inside_coverage;

  inside_coverage = gsk_rounded_rect_coverage(gsk_decode_rect(transformed_inside_outline), frag);
  float alpha;

  if (inside_coverage == 1.0)
    alpha = 0.0;
  else
    {
      float outside_coverage;

      outside_coverage = gsk_rounded_rect_coverage(gsk_decode_rect(transformed_outside_outline), frag);

      alpha = clamp(outside_coverage - inside_coverage, 0.0, 1.0);
    }

  gskSetOutputColor(final_color * alpha);
}