precision mediump float;
varying mediump vec2 vTexCoord;
varying mediump vec3 vLightDirection;
varying mediump vec3 vHalfVector;
uniform sampler2D sDiffuse;
uniform sampler2D sNormal;
uniform sampler2D sGloss;
uniform lowp vec4 uColor;

void main()
{
  vec4 texture = texture2D( sDiffuse, vTexCoord );
  vec3 normal = normalize( texture2D( sNormal, vTexCoord ).xyz * 2.0 - 1.0 );
  vec4 glossMap = texture2D( sGloss, vTexCoord );

  float lightDiffuse = max( 0.0, dot( normal, normalize(vLightDirection) ) );
  lightDiffuse = lightDiffuse * 0.5 + 0.5;

  float shininess = pow (max (dot (normalize( vHalfVector ), normal), 0.0), 16.0);

  gl_FragColor = vec4( texture.rgb * uColor.rgb * lightDiffuse + shininess * glossMap.rgb, texture.a * uColor.a);
}