Lower unpegged problem

[z34chris]

I have come to notice that the lower unpegged attribute only works correctly when the difference between the ceiling and floor of the two sided line the texture is on is 128. If the floor goes lower the texture remains in the same place. If the ceiling shifts any the texture shifts along with it. On a one sided line the texture is drawn from the bottom up like it is supposed to but this does not seem to be the case with a two sided line. This would seem like a situation where folks would have texture alignment problems. I was wondering why the doom engine handles two sided lines in this fashion instead of the way that one sided lines are handled?

[jobro]

Because that your double sided line most likely has an upper and a lower texture. Try upper unpeg it, and it should solve your problem.

[z34chris]

That will align the textures with the wall. What I am doing is aligning textures from the floor. Although they are not used too often, a few textures will be aligned from the floor and others will be aligned from the ceiling. My original question was about the quirky behavior of lower unpegging on a two sided line vs a one sided line. The way I look at it, the lower unpeg should work exactly on a two sided line the way it works on a one sided line. I experimented with lower unpegging and see no reason why it behaves badly on a two sided line. Other than lining up a texture with the rest of the wall, this function is nearly useless on a two sided line.

[Graf Zahl]

It behaves that way so that aligning textures below a window is easier because that's the most common use for this.

[z34chris]

Perhaps it is the only use ;)

[z34chris]

I looked through the doom maps and found a few places where Id used the lower unpegged attribute on a two sided line but only to no avail. The line's lower texture is one that has slop on the bottom edge from the nearby pool of liquid. When playing the level the appropriate part of the texture never shows. Examples of this are the pool bridges in E2M1 and E2M4. I have never yet seen Id use x/y offsets only the unpegging attributes and floor/ceiling height tricks to make the lower unpeg work. From these examples the code was not completely implemented for lower unpegging.