code: public void setTexture(String key, GVRTexture texture)
      {
          checkStringNotNullOrEmpty("key", key);
          synchronized (textures)
          {
              textures.put(key, texture);
              NativeShaderData.setTexture(getNative(), key, texture != null ? texture.getNative() : 0);
          }
      }
docs: Bind a {@link GVRTexture texture} to the shader uniform {@code key}.
  
  @param key       Name of the shader uniform to bind the texture to.
  @param texture   The {@link GVRTexture texture} to bind.