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?
Removed infinite details and went for decreasing details with the distance instead (like the axis aligned ortho view auto sized grid).
Separate drawing of the Z axis into 2 pass (using shading group) to render ordered transparency with the main grid pass.
We render selected meshes into another buffer and use a screen space shader to expand the color out of the mesh silouhette.
Pros: only one additionnal render pass is needed (like old outline code), and we have occluded informations.
Cons: memory usage is a problem. This method needs 2 color buffer to ping pong when expanding the outline and 1 depth buffer to test occluded fragments. This gives a 88 bits/pix memory footprint.
Idea: Since we don't need all color range but only some uniform colors (theme colors) we could manipulate only the color ID instead of the whole color this could cut the color buffer size and lower the memory footprint to 58 bits/pix.
It also adds nice occluded silouhette information for selected objects that are behind visible objects.
This methods is really heavy because it needs to render the wires twices.
