export default /* glsl */`
#ifdef USE_NORMALMAP

	uniform sampler2D normalMap;
	uniform vec2 normalScale;

#endif

#ifdef USE_NORMALMAP_OBJECTSPACE

	uniform mat3 normalMatrix;

#endif

#if ! defined ( USE_TANGENT ) && ( defined ( USE_NORMALMAP_TANGENTSPACE ) || defined ( USE_CLEARCOAT_NORMALMAP ) )

	// Normal Mapping Without Precomputed Tangents
	// http://www.thetenthplanet.de/archives/1180

	mat3 getTangentFrame( vec3 eye_pos, vec3 surf_norm, vec2 uv ) {

		vec3 q0 = dFdx( eye_pos.xyz );
		vec3 q1 = dFdy( eye_pos.xyz );
		vec2 st0 = dFdx( uv.st );
		vec2 st1 = dFdy( uv.st );

		vec3 N = surf_norm; // normalized

		vec3 q1perp = cross( q1, N );
		vec3 q0perp = cross( N, q0 );

		vec3 T = q1perp * st0.x + q0perp * st1.x;
		vec3 B = q1perp * st0.y + q0perp * st1.y;

		float det = max( dot( T, T ), dot( B, B ) );
		float scale = ( det == 0.0 ) ? 0.0 : inversesqrt( det );

		return mat3( T * scale, B * scale, N );

	}

#endif
`;
