... display vertex even when occluded.
Add back the vertex display because occluded vertex are not visible when
the triangle is almost parallel to the view.
The problem with the barycentric coord is that they are hard to work with
and their derivatives not enough precise to compute the vertex positions.
So we need to pass the vertices scree positions down to the fragment shader.
This decouple the vertex display from the face+edges.
This is to reduce the number of triangles required to fix the edges
artifacts (aliasing) and increase viewport reactivity when not actively
navigating (ie. mouse scroll).
Also it makes all vertices visible (not cut-off) even when navigating.
However it makes the navigation drawing a bit slower because it has to
render twice.
Also add a depth bias to the wires to avoid depth fighting when previewing
final mesh (modifiers applied).
This rewinds a change from own commit e3d88b021c
The only took edge overlay into account (crease, seam.. etc)
Currently active-face also uses this width.
While the difference is subtle,
this makes the active-face stand out more clearly.
Remove all the clip cases and just pass the vertices screen position to the
fragment shader.
This does put a bit more pressure on the fragment shader but it seems to be
faster than before. And it simplify the code a lot.
It seems to fix some long standing issue on some intel GPU.
- Vertex size now matches the theme setting.
- Edge width is closer to a single pixel line.
- Face dot was scaled up to be drawn as a circle,
but is currently a square.
This introduce some little artifacts on the border of edges because some pixel with very low opacity does not get discarded and then occlude the face rendered behind if it has not been drawn yet.
To fix this. I added an offset in the geometry shader for the edge fixup. This make the artifact only visible on the border of the object if there is a very dense wire region. It's only visible in edge select mode since vertex and face center also hides the artifacts.
We can enable this only if AA is enabled but for now it's always enabled.
Shader stages need to agree about interpolation qualifiers. Apparently implicit smooth (the default) and explicit smooth are considered different by some GLSL compilers. Found by @letterrip on Linux + Intel.
Follow-up to 941e739d70
