flatbox_egui 0.1.0

Egui binding for Flatbox engine
Documentation 
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#version 450

#define I in
#define O out
#define V(x) x

uniform vec2 u_screen_size;
I vec2 a_pos;
I vec4 a_srgba; // 0-255 sRGB
I vec2 a_tc;
O vec4 v_rgba;
O vec2 v_tc;

// 0-1 linear  from  0-255 sRGB
vec3 linear_from_srgb(vec3 srgb) {
  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
  vec3 lower = srgb / vec3(3294.6);
  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
  return mix(higher, lower, V(cutoff));
}

vec4 linear_from_srgba(vec4 srgba) {
  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
}

void main() {
  gl_Position = vec4(2.0 * a_pos.x / u_screen_size.x - 1.0,
                     1.0 - 2.0 * a_pos.y / u_screen_size.y, 0.0, 1.0);
  // egui encodes vertex colors in gamma space, so we must decode the colors
  // here:
  v_rgba = linear_from_srgba(a_srgba);
  v_tc = a_tc;
}