precision highp float;

uniform sampler2D NormalMap;

in vec3 Normal;
in vec4 Tangent;
in vec3 Bitangent; // TODO: Compute here or in PS?
in vec2 Texcoord;

out vec4 FragColour;

// TODO: Move to "normal.h"
vec3 get_vs_normal(vec3 normal, vec4 tangent, vec3 normalMapSample) {
  vec3 N = normal;
  // vec3 T = normalize(interpTangent   - dot(tangent, N)*N);
  // vec3 B = normalize(interpBitangent - dot(interpTangent, N)*N - dot(interpTangent, T)*T);
  vec3 T = tangent.xyz;
  //vec3 B = tangent.w * cross(N,T);
  vec3 B = Bitangent;
  vec3 n = normalMapSample;
  return normalize(n.x*T + n.y*B + n.z*N);
}

void main() {
  vec3 normalMapSample = texture(NormalMap, Texcoord).xyz * 2.0 - 1.0;
  vec3 N = get_vs_normal(Normal, Tangent, normalMapSample);
  FragColour = vec4(pow(N, vec3(1.0 / 2.2)), 1.0);
}