Possible regression in euc 0.4.1

[CryZe]

I'm seeing some weird artifacts with euc 0.4.1:

Before:

After:

The 4 of the main points meter has a weird line going through it.

[zesterer]

Interesting. How are those numbers currently rendered?

[CryZe]

I'm getting the glyphs from rusttype and then triangulate them with lyon. So they are basically just normal meshes. There shouldn't be a gap there as the two adjacent triangles there don't have a gap, as they are sharing the same vertices.

[zesterer]

euc's vertex shader now expects [f32; 4] as part of the return type, but I see that's not happening in your code. What happens if you emit 1.0 as the last value?

[CryZe]

That's what I'm doing here. I didn't push the changes yet. Without a fourth f32 value, it wouldn't build.

[zesterer]

Would it be possible to put together a setup that demonstrates the problem such that I can try to figure out what's going on? I have a few suspicions, but it's difficult for me to confirm them without a way to test them.

[CryZe]

I'll try to replicate it in a small-ish test.

[CryZe]

Okay, this is really odd. If I disable alpha blending, the problem goes away O.o

[CryZe]

It seems like the color values are completely out of range.

[CryZe]

Yeah, that's a line where the input color is NaN apparently.

[zesterer]

I suspect that a NaN is generated somewhere in the rasterizer for a 0-width triangle or something like that, and that this gets propagated to the blending code.

[CryZe]

Here's the code as a gist: https://gist.github.com/CryZe/ab4544126b6e0b6660364066cc818714

[CryZe]

It's a white line in this because I do .min(255.0) at the end.

[CryZe]

The line is at y=362, x>=198, x<=208

[CryZe]

The triangle that causes it seems to be this one:

    let mesh = [
        Vertex {
            position: Vec2 {
                x: 0.39804077,
                y: -0.21000671,
            },
            texcoord: Vec2 {
                x: 0.0,
                y: 0.36832988,
            },
        },
        Vertex {
            position: Vec2 {
                x: 0.27268982,
                y: -0.21000671,
            },
            texcoord: Vec2 {
                x: 0.0,
                y: 0.36832988,
            },
        },
        Vertex {
            position: Vec2 {
                x: 0.44769287,
                y: -0.21000671,
            },
            texcoord: Vec2 {
                x: 0.0,
                y: 0.36832988,
            },
        },
    ];

[CryZe]

And yeah, looks like that's a straight line as all y coordinates are the same.

[zesterer]

Okay, I've found the bug. As suspected, it was a NaN that got propagated throughout the texture projection code. I'm pushing a fix now (I'll publish a new version too).

[zesterer]

euc 0.4.2 now includes the patch.

[CryZe]

Looks like that fixed it in all of my tests. Thank you for figuring this out :D