[oden] Re-work the way that scaling works

This is part of making the text scale properly, you'll see.

src/util.wgsl

@@ -0,0 +1,68 @@
+// 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,
+  zoom : 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 * screen.zoom * 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;
+}
+
+*/