This adds a custom depth test that have the benefits to glitch less and be more visually pleasing.
Downside is that it let the grid pass trough the objects a little.
This effect is done in NDC space so that it counteract the logarithmic depth distribution imprecision (read as it's less visible near the camera but more present far away).
This patch also includes some cleanups.
This required some small changes to the data display shaders so that they match the way the object mode renders them.
Strangely enough, I had to remove the normal attribute from the display code because it was being not bound as soon as I created another rendering call in object mode. The problem may be deeper but I did not have time for this so I derive the normal from the sphere pos.
Adds a FXAA for smoothing out the extracted outlines.
The Post Process Anti Aliasing is only done on the Alpha channel of the outlines.
Because of that we need to add bleed the outline color out of the silouhette so the AA'd alpha can blend the right color and not pick black when the alpha is smoothed out of the silhouette.
Also because of the AA needs to have clear contrast to work with, I decided to ditch the "bluring" or the occluded outlines.
The FXAA adds an overhead of 0.17ms but we gain back 0.22ms * 4 = 0.88ms by removing the blur.
The FXAA Implementation is from Corey Richardson (cmr) (D2717). I had to modify it a bit to only filter the alpha channel.
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.
I couldn't reproduce either, but calling min() with different argument
data types and indexing vectors with an index not known at compile time
seem likely to cause problems.
Ref T52404, T52404.
Group texture fetches to hide latency. 3.2ms -> 2.2ms (constant time improvement, not depending on scene complexity)
Could optimize further with textureGather (require OpenGL 4.0).
We now floor the corner position and use this position as origin.
This gives us perfect derivatives in all cases even if very far from the origin.
Unfortunately this won't fix the low precision of coordinates used for computing the actual grid size, resulting in thick, non-smoothed lines.
Also did a bit of refactor how the axes are drawn.
Do not use the inverse perspective matrix inside the shader to recover world positions.
That leads to severe float imprecision leading to nasty artifacts.
Instead we compute the world view vector for each pixels and do a ray to plane intersection.
We are still getting low precision derivatives when going far away from the origin, and thus artifacts.
This commit also fixes the non-appearing negative Z axis in 3D view.
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
vertexColor output was not being written --> shader failed to link --> assert hit while setting that shader's uniforms.
Vertex attribs are smooth by default, so I shortened the declaration.
@fclem or @dfelinto: is color = 0 ok here?
