Perspective Transformation of 2.5D Orthographic Graphics

We updated Retro Commander to allow to render all 2.5D orthographic top-down graphics using a perspective transformation, to make it appear more 3D-like. Enable the "Parallax" option in the game's settings.

The perspective transformation should increase immersion by adding a 3D look and feel. The transformation matrix has been applied as follows to a 3D-Matrix. dx represents the intensity of the effect, e.g. 0.001. Rendering is orthographic if the value is 0.0.

  // source quad position (4 points)
  -1.00f     , -1.00f,
  +1.00f     , -1.00f,
  +1.00f     , +1.00f,
  -1.00f     , +1.00f,

  // target quad position (4 points)
  -1.00f     , -1.00f,
  +1.00f     , -1.00f,
  +1.00f + dx, +1.00f,
  -1.00f - dx, +1.00f

To counter the effect for objects on the maps, those objects are rendered with the transformation reversed. Otherwise, objects would be leaning towards the inside and make the 3D-effect go away.

  // calculate xL & xR based on their position on the screen
  xL = ...
  xR = ...

  // source quad position (4 points)
  -1.00f + xL, -1.00f,
  +1.00f + xR, -1.00f,
  +1.00f     , +1.00f,
  -1.00f     , +1.00f,

  // target quad position (4 points)
  -1.00f     , -1.00f,
  +1.00f     , -1.00f,
  +1.00f     , +1.00f,
  -1.00f     , +1.00f

There are few problem areas doing so.

• The mouse coordinates need to be calculated for the transformation (although doable fairly easily).
• While orthographic graphics are crisp, doing a transformation will make the view slightly more "blurry".
• Does this generally improve the look and feel?
• Undoing the transformation for connected objects such as walls or mountain ranges will introduce ugly offsets and potential gaps.

Reference for Rendering Problems:

Download and test the feature now. The game is available from the following sites.

• Official Site: RetroCommander.com
• PC, Mac, Linux: Steam, itch.io, Epic Games
• Android: Google Play
• iOS: Apple

Reference Video: