Sky masking polygons should not be visible
As seen in this screenshot, there are sky masking polygons visible in Hexen MAP02.There is a number of potential reasons why this is happening:
- Regression due to DGL refactoring
- Color writes should be disabled when drawing sky mask
- Some other incorrect DGL state
Fixed|Renderer: Black segments visible in the sky
Don't clip with polyobj walls in a sky-ceiling sector.
Calls for a closer investigation as to why the sky gets occluded if this check is disabled.