// base coordinates & color expressions for shader-graph


// fraction is saturation percentage, 0 means gray
vec3 Desaturation(vec3 color, float fraction)
{
  vec3 gray = vec3(dot(color, GRAY_VECTOR));
  return mix(color, gray, fraction);
}

vec2 Rotator(vec2 uv, vec2 centerUV, float time, float speed)
{
  uv -= centerUV;
  vec3 dir = vec3(uv.x, 0.0, uv.y);
  float dirLength = length(dir);
  dir /= dirLength + EPSILON;
  dir = RotationVecFromAxisY(dir, time * speed) * dirLength;
  return vec2(dir.x, dir.z) + centerUV;
}

// return 0.0 when out of range
// hardness: 0 - 1
float SphereMask(vec2 center, vec2 point, float radius, float hardness)
{
  float length = length(center - point);
  float coef = pow(saturate(length / radius), 1.0 / (1.0 - saturate(sqrt(hardness)) + EPSILON));
  return length > radius ? 0.0 : 1.0 - coef;
}
float SphereMask(vec3 center, vec3 point, float radius, float hardness)
{
  float length = length(center - point);
  float coef = pow(saturate(length / radius), 1.0 / (1.0 - saturate(sqrt(hardness)) + EPSILON));
  return length > radius ? 0.0 : 1.0 - coef;
}


// For Fragment Shader

// tangent space -> world space
// same as TransformVector
vec3 TransformNormalMap(vec3 vectorFromNormalMap)
{
  vec3 vectorTS = normalize(vectorFromNormalMap - vec3(0.5));
  vec3 normal = normalize(FSInput_worldNormal);
  vec3 tangent = normalize(FSInput_worldTangent);
  vec3 binormal = CalculateBinormal(normal, tangent, FSInput_mirrorNormal);
  vec3 vecWS = vectorTS.x * tangent + vectorTS.y * binormal + vectorTS.z * normal;
  return vecWS * vec3(1.0, 1.0, -1.0); // inverse Z for RH
}

// WorldPos -> UV
vec2 GetTriplanarMappingUV()
{
  vec3 Up = vec3(0.0, 1.0, 0.0);
  vec3 U = cross(Up, FSInput_worldNormal.xyz);
  if (length(U) < 0.01)
    U = vec3(1.0, 0.0, 0.0);
  else
    U = normalize(U);
  vec3 V = cross(U, FSInput_worldNormal.xyz);
  V = normalize(V);
  return fract(vec2(dot(FSInput_worldPos.xyz, U), dot(FSInput_worldPos.xyz, V)));
}