Recently the snap to edges has been changed to work with coordinates 2d. Thus, the lambda of the snap pointon on edge becomes different from the actual lambda in a 3d edge.
The solution to correct the lambda was this:
```
if (is_persp) {
const float fac = depth_a / (depth_a + depth_b);
lambda *= (1.0f + (fac - 0.5f) * (1.0f - lambda));
````
...
But the lambda was still not very accurate.
Now the function uses the `dist_squared_ray_to_seg_v3` to get the coordinate of the snap point on the edge. And then tests that point.
The accuracy returned to normal values.
06908955c3