Fullscreen Outline Shader

[wooden schooner]

I followed a guide to create a fullscreen outline shader and it works well, but I have a couple issues.

In the first image, the shader doesn't add an outline to the top side of the voxels for some reason.

In the second image, the shader doesn't add an outline on this edge.

I will admit I am very inexperienced when it comes to shaders, but I've tried many different shaders to try and get these outlines in my voxel game, and this is the only one that has gotten this far. I would just like to fix these couple of issues.

I attached an image of the shader, and this is the guide I used: https://www.youtube.com/watch?v=VGEz8oKyMpY

Also bonus: if you know how to make the outlines look a bit more anti-aliased instead of pixely that'd be great too

[raven juniper]

It looks like you are detecting discontinuity using normals and color, but in this example those are the same between two distinct surfaces

I recommend checking out this article
https://ameye.dev/notes/rendering-outlines/#sources-of-discontinuity
Specifically "sources of discontinuity" and "custom discontinuity source"

[wooden schooner]

ah ok now that i understand what normals are, it does make sense why im having this issue. But do you know what other source of discontinuity could accomplish what im looking for here?

i do see that "depth" is an option according to the link you sent but im not sure if thats exactly what i want or how to implement

also maybe its important to note its a voxel game if that simplifies anything

[raven juniper]

Like you are comparing the difference of normals and color between samples, comparing difference in depth would detect an edge between the top of the cube and the background behind it further away, as well as between different parts of the cube

[wooden schooner]

ok cool so really i dont even need normals at all if i do that

[raven juniper]

It seems like a perfect solution, but the downside is it's not very accurate, especially at glancing angles or objects that are making contact

[wooden schooner]

wdym by this

should be fine for voxels no?

there wont be moving objects

its just a building game

[raven juniper]

If there will be no objects that can touch the voxels, that won't be an issue
Glancing angles might be, when view a voxel nearly from the side, one of the sides will have a steep depth difference and may become fully painted as outline

[wooden schooner]

ah

yea thats an issue then

[raven juniper]

The opposite issue may be that corners facing the camera have very little depth difference and might not draw outlines at all

Which is why it's not uncommon to mix methods to their advantages, though that can get expensive to render

The custom discontinuity source method like the image demonstrates involves arbitrary colors for different parts of meshes which are only used for the edge detection

Very precise control, and usually doesn't require any other texture maps, but is more work

[wooden schooner]

so that method would work? just gotta figure that out then