Consider Extracting RenderTransform From DrawDevice

[ilexp]

Summary

Over the course of issue #219 it became apparent that it might be useful to separate render matrix handling and API from actual drawing API. That way, Camera could internally have a general RenderTransform for coordinate transformation, and a DrawDevice for the actual rendering - instead of two DrawDevice instances with all the overhead.

Analysis

• The name of the new class is not final. Consider other alternatives and find the best.
• DrawDevice would internally keep a RenderTransform instance and expose it via property.
• All of the transform API related DrawDevice code could be removed from DrawDevice entirely. This would clean it up a lot.
• Other related transform API code in CamViewClient and similar could be replaced with a new getter property as well.
• More advanced transform functionality would only need to be implemented in the new RenderTransform class, not spread out over various classes and APIs.

[ilexp]

Progress

• Created the new feature/3.0/rendertransform branch to work on this.
• Set up a RenderTransform class by copying the relevant DrawDevice parts.

Immediate ToDo

• Remove RenderMode from RenderTransform entirely, solve through configuration instead.
  • Actually, consider replacing it entirely with a third ProjectionMode.
• Write unit tests for RenderTransform.
  • Move existing transform related DrawDevice tests.
  • Write more tests where appropriate.
• Replace all related DrawDevice code with forwarding to an internal RenderTransform instance.
• Replace public DrawDevice API with exposing the internal RenderTransform instance where it makes sense. Adjust IDrawDevice as well as the sites that use it accordingly.
• Replace the internal transformDevice in Camera with a RenderTransform instance.

[ilexp]

Progress

• Merged RenderMode into ProjectionMode by adding Screen projection in addition to Orthographic and Perspective.
• Removed RenderMode dependent code from the graphics backend and replaced it with additional rendering options for de/activating depth testing and depth writing.
• Removed DrawDevice.DepthWrite property, as this should be considered an implementation detail by all renderers.

Immediate ToDo

• Replace all related DrawDevice code with forwarding to an internal RenderTransform instance.
• Replace public DrawDevice API with exposing the internal RenderTransform instance where it makes sense. Adjust IDrawDevice as well as the sites that use it accordingly.
• Replace the internal transformDevice in Camera with a RenderTransform instance.
• Write documentation for RenderTransform, XML comments for at least all public API.
• Write unit tests for RenderTransform.
  • Move existing transform related DrawDevice tests.
  • Write more tests where appropriate.

[ilexp]

Progress

• Proceeded to extract all RenderTransform code from DrawDevice and started to refactor, but found the overall design somewhat unwieldy and inconvenient. Also, having to use some rendering properties on a sub-object of DrawDevice, but not others, felt a bit artificial. Decided to revert the main work on this issue, but kept some changes (like RenderMode and DepthWrite) that occurred along the way.
• Added RenderOptions properties for depth testing and depth writing.

Closing this.