// This file contains utility functions to be used by the other shaders.
// Sorry that WGSL has no direct linking/reference/include function,
// you just kinda have to know it.

// ----------------------------------------------------------------------------
// Resolution Handling
// ----------------------------------------------------------------------------

struct ScreenUniform {
  resolution : vec2f,
};
@group(0) @binding(0) // 1.
    var<uniform> screen : ScreenUniform;

fn adjust_for_resolution(in_pos: vec2<f32>) -> vec2<f32> {
  // The incoming positions are all in pixel space on the screen, we need to
  // convert them into clip space, from (-1,-1) to (1,1). (-1,-1) is in the
  // bottom-left corner.
  //
  // Put result in the range [0-2], where (2,2) is the bottom-right corner
  // of the screen.
  var result = (in_pos * 2.0) / screen.resolution;

  // Put result in the range [-1,1] where [1,1] is the bottom-right corner
  // of the screen.
   result -= 1.0;

  // Put result in the range [-1,1] where [1,1] is the top-right corner of
  // the screen.
  result.y = -result.y;

  return result;
}

/**

const RES = vec2f(320.0, 240.0); // The logical resolution of the screen.

fn old_adjust_for_resolution(in_pos: vec2<f32>) -> vec2<f32> {
  // Adjust in_pos for the "resolution" of the screen.
  let RES_AR = RES.x / RES.y; // The aspect ratio of the logical screen.

  // the actual resolution of the screen.
  let screen_ar = screen.resolution.x / screen.resolution.y;

  // Compute the difference in resolution ... correctly?
  //
  // nudge is the amount to add to the logical resolution so that the pixels
  // stay the same size but we respect the aspect ratio of the screen. (So
  // there's more of them in either the x or y direction.)
  var nudge = vec2f(0.0);
  if (screen_ar > RES_AR) {
    nudge.x = (RES.y * screen_ar) - RES.x;
  } else {
    nudge.y = (RES.x / screen_ar) - RES.y;
  }
  var new_logical_resolution = RES + nudge;

  // Now we can convert the incoming position to clip space, in the new screen.  
  let centered = in_pos + (nudge / 2.0);
  var position = (2.0 * centered / new_logical_resolution) - 1.0;
  position.y = -position.y;
  
  return position;
}

*/