Actually the upper part of the retracting ladder is 10 pixels wide.
Ah, I forgot about that. Therefore, that means ...
I have a savestate that shows that it is safe to go if the left eye directly lines up with the right vertical line of the ladder, but I think that one pixel further left would make it unsafe.
This is true.
are you saying the black lines overlapping is not yet a collision? then yeah, they both could be moved in one more pixel on each side.
I'm pretty sure from Ethan's example on page one, that would be considered a collision.
Yes, this is unfortunate. If you follow the thread, I pointed out this mistake two posts later, but Ethan never fixed the images for collisions. Every one of those examples posted for collisions are all errors -- they are all misses.
I've been using the term "tangent" to mean that the EDGE of the hitbox is SHARED by two objects. This term might be confusing, I'm not sure. By overlapping, I mean that the hitboxes must completely cross over each other so that the edges are no longer shared, but are overlapping each other. Again, maybe not the best term, but I've used these terms consistently and it's the best way that I can describe it.
This can easily be seen in the code. The code makes checks that use the < operator as opposed to the <= operator before a hit is registered. In other words, if the edges have an EQUAL x-coordinate (or y-coordinate), it is NOT a hit.
But this is considered a hit:
Jeff, please double check that -- that cannot possibly be true. Your diagrams show the same number of pixels between the two centers, which, from the code would mean that they would have to be both misses or both hits. In this example, they should both be misses.
You should double check that the fireball in question was not actually using the OTHER fireball sprite, which actually has a different size visually and so perhaps a different amount of the sprite can overlap without causing a collision.
It would be pretty shocking to me if the center actually changes depending on if it's a left facing sprite or a right facing sprite, especially since these sprites all have an odd number of visual pixels horizontally. That just wouldn't make sense to me.
SIDE NOTE: I just noticed that Jumpman's hitboxes of his other sprites in Ethan's diagram are wrong. They are both one pixel too tall (notice that the black box extends one pixel higher than it does for our hunched over sprite, which is correct).