Peak and Round buttons

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Peak and Round buttons

Postby squirrelhavoc » Sun Jul 23, 2006 10:40 pm

How do the Peak and Round buttons work? They seem to only do something when I click them, then create a new spline, then it isn't all the time. If I want to modify an existing spline, they don't seem to do anything.
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Postby dcuny » Mon Jul 24, 2006 3:28 am

These controls work by changing the attributes of the selected control points. So to use them, you need to first select control points to modify, and then choose the Peak or Curve button.

By default, JPatch interpolates smooth curves through control points. For something like a table or a cube, you might want "sharp" edges instead. If you select control points and then choose Peak, JPatch treats these points as "sharp" edges. Curve restores the points back to their default behavior.

Check out this article in the JPatch wiki. for some examples.
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Postby pndragon » Mon Jul 24, 2006 4:02 am

If I want to modify an existing spline, they don't seem to do anything.

I was having the same problem. Sascha has changed the function of the peak and round buttons so that they only effect new splines. So pushing either button all by itself would have no visible immediate effect.

For example: The default is round. You make several splines with round points and then push the peak button. From then on all splines are created with peaked points and all of the previously made points remain round.

To modify an existing point/spline: Select the point or spline you wish to change, open Edit > Tools > Change Tangents > Peak or Round. I suggest you edit your keyboard shortcuts and assign hotkeys to both of these.

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Postby sascha » Mon Jul 24, 2006 10:42 am

My advice is to don't use the peak/round tangent modes at all (that is, leave it at "round").
People tend to use it to do polygon-based modeling with a patch modeler, which generally is not a good idea.
I seriously consider to disable this feature.

If you need a peak edge, use the ALT key when appending another cp to it - in effect this will append a different spline.
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Postby pndragon » Mon Jul 24, 2006 11:05 am

My advice is to don't use the peak/round tangent modes at all

Just out of curiosity... Why?

I have never used them very much to begin with and since I received what are basically the same instructions as those the above I have used them even less. It is just too much work.

--- Jim
"We're so sorry, Uncle Albert,
But we haven't done a bloody thing all day."
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Postby sascha » Mon Jul 24, 2006 11:40 am

Just out of curiosity... Why?

Because JPatch has a concept of curves. Although curve-segments are similar to edges of polygon models, polygon models generally do not have this concept.

Normally it's easy to recognize a curve - it's a set of controlpoints connected with a smooth spline that goes through these controlpoints.

To form patches, you'll have to create a "spiderweb" of curves (you do this by attaching points of one curve to points of another curve). Suddenly one visible point belongs to two curves (although internally it's still two controlpoints), but you can still distinct the two curves because the segments of one curve connect smoothly.

Imagine this configuration:
Code: Select all
  1
  |
2-3-4
  |
  5


If the curves 1-3-5 and 2-3-4 are (smooth) splines, you can easily recognize them as curves. But if you switch the tangent mode to peak, this visual clue is lost. The curves could also go 1-3-2 and 4-3-5, who can tell? JPatch doesn't have any problem with it, it's the user who suddenly can't distinct between different curves vs. peak edges (on the same curve).

Now given that the rules that define what's a valid patch and what's not are not trivial to understand, this is a real problem. If you append a point you have no indication wheter JPatch appended it to the curve you wanted it to be. I tried to create some models with hard edges using the peak mode, but eventually gave it up.

If you can't live without them, my advice is to model the thing with round tangents (so you can actually see what's going on), and make the tangents peak once the model is finished.
But I really can't imagine any hard edge that can't be modeld with the "attach instead of append" trick (holding down ALT when welding), that's why I think about abandoning the peak-feature (and auto-convert all peak connections to attached ones when loading an old file or importing an A:M or sPatch model).
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Postby pndragon » Mon Jul 24, 2006 12:08 pm

you can easily recognize them as curves.


That's one reason why I use them as little as possible. It is very easy to get confused.

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