Ethan A Merritt wrote:
> On Saturday 20 May 2006 01:57 pm, Daniel J Sebald wrote:
>
>>Ethan A Merritt wrote:
>>
>>>I never did understand 'set ticslevel', but whatever it did should
>>>stay that way for backwards compatibility.
>>>
>>>The idea behind 'set xyplane <foo>' is [supposed to be] obvious:
>>>Whatever zrange is, whatever way round the axes are pointing,
>>>yadda yadda, draw the plane so that it intersects the z axis
>>>at <foo>.
>>
>>'set xyplane *at* <foo>' does as you explain, and that works just as advertised.
>>
>>The problem is the "percentage of z-axis" form, i.e.,
>>the non "at" form, the form for which the actual values on the z-axis do not matter;
>>rather the user wants the xyplane to be somewhere relative to the z-axis visually.
>
>
> Then let's just get rid of the "no at" form for 'set xyplane'.
> I don't see a need for it.
>
> With Petr's patch to export GPVAL_Z_MIN and GPVAL_Z_MAX,
> you can accomplish the same thing by saying
> set xyplane at func(GPVAL_Z_MIN,GPVAL_Z_MAX)
I don't totally follow what "func" does. But there may be another problem, one Hans corrected me on something I said in a previous post. The bottom of the z-axis may not be z_min, if increasing numbers run downward instead of upward. (That is why I've been making this distinction with "bottom" and "top".)
The idea of a relative placement of the xyplane isn't bad. It's just that the current ticslevel logic evades me: if I want the xyplane 20% below the z-axis I type 0.2 and if I want the xyplane 20% above the z-axis I type -1.2. One can see how that ends up being a trial and error process. Whereas, I'd think -1.2 for 20% below and 1.2 for 20% above would be easy to comprehend.
Getting rid of the "no at" form of xyplane would be fine too, as a means of not propagating a confusing syntax. Instead maybe we could use
"set xyplane below 0.2"
"set xyplane above 0.2"
meaning set the xyplane 20% below *z_bottom* or set the xyplane 20% above *z_top*. To get the xyplane to the center of the z-axis one could type either
"set xyplane below -0.5"
"set xyplane above -0.5"
I don't know if that is very good. Somehow I like the -1/+1 approach because then to get the xyplane at the center of the z-axis one just types
"set xyplane 0"
It's all one's frame of reference really.
Dan
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