#version 450 core
layout(location = 0) out vec4 oColor;

layout(std140, binding = 0) uniform PerFrame {
  mat4 uView;
  mat4 uProj;
  vec4 uLightDir; // unused
};
layout(std140, binding = 2) uniform Material {
  vec4 uAlbedo; // unused
};

layout(location = 0) in  vec3 vDir;

// sRGB-tuned colors; we’ll convert to linear before mixing
vec3 srgb2lin(vec3 c){ return pow(c, vec3(2.2)); }
vec3 lin2srgb(vec3 c){ return pow(c, vec3(1.0/2.2)); }

void main() {
  // nicer defaults (tweak to taste)
  vec3 skyTopL     = srgb2lin(vec3(0.15, 0.35, 0.75));
  vec3 skyHorizonL = srgb2lin(vec3(0.75, 0.85, 0.98));

  vec3 dir = normalize(vDir);

   float t = clamp(dir.z * 0.5 + 0.5, 0.0, 1.0); // (B) world up = +Z

  // shape the gradient a bit
  t = pow(t, 1.45);

  vec3 colorL = mix(skyHorizonL, skyTopL, t);
  oColor = vec4(lin2srgb(colorL), 1.0); // manual gamma (your default FB isn’t sRGB)
}