module Funfriend::GL
  extend self

  def buffer_data_array(target : Enum, data : Array, usage_hint : Buffer::UsageHint)
    data_size = data.reduce(0) {|memo, i| memo + sizeof(typeof(i))}
    LibGL.buffer_data(target, data_size, Pointer(Void).new(0), usage_hint)

    offset = 0
    data.each do |byte|
      size = sizeof(typeof(byte))
      LibGL.buffer_sub_data(target, offset, size, pointerof(byte))
      offset += size
    end
  end

  def shader(fragment_filename : String, vertex_filename : String) : Program
    vertex_shader_source = FileStorage.get(vertex_filename).gets_to_end
    fragment_shader_source = FileStorage.get(fragment_filename).gets_to_end

    vertex_shader = VertexShader.create(vertex_shader_source)
    fragment_shader = FragmentShader.create(fragment_shader_source)

    shaders = {vertex_shader, fragment_shader}
    Program.create(shaders)
  end
end