perspective molds

[Ed Nadie]

The default perspective mold is the useful one. The four presets (left, right, floor, ceiling) are pointless variations -- since they ignore foreshortening, you usually end up having to move at least two corners anyway, and gain no advantage over the general p-mold.

I had high hopes about being able to paste custom perspective molds, but they give wacky results. I tried pasting molds on various freeform shapes, and the vanishing points were all over the place and incompatable with eachother. I thought maybe if I temporarily grouped a freeform shape with a square, and applied the custom mold to the square, it might give the correct perspective, but no...

The attachment shows the creation of a custom mold in the shape of a measured perspective square (green), pasted on the target square (orange), which should have changed to recreate the shape of the custom mold, but it didn't (blue); so forget any controllable results with the custom perspective mold -- any other target shape will be nothing but wackier.

The custom mold doesn't give good results for three reasons that I can see:
1) The mold ignores foreshortening!
2) The mold conforms to a rectangular approximation of the object, instead of calculating from an absolute space squarely centered on the object.
3) As the stacked figures show, the resultant 'hello kitty?' shape continues the slope of the mold's top line, but translates the bottom line horizontally (marked in cyan). An algorithm based on Dig-Dug tunnelling from prison?

I'm disappointed, but my experiments show the so-called custom perspective molds are an exercise in wackyness and add nothing to the default perspective mold.

I've found the default perspective mold can in fact be used for controlled results if the object to be molded is first centered on an enveloping square and grouped, then the molded composit is stretched to conform to a known perspective square.

I would gladly purchase a usable perspective plug-in. And if anyone has any ideas about drawing in perspective with vectors, I'd like to hear them...

Ed Nadie

[Ed Nadie]

The default perspective mold is the useful one. The four presets (left, right, floor, ceiling) are pointless variations -- since they ignore foreshortening, you usually end up having to move at least two corners anyway, and gain no advantage over the general p-mold.

I had high hopes about being able to paste custom perspective molds, but they give wacky results. I tried pasting molds on various freeform shapes, and the vanishing points were all over the place and incompatable with eachother. I thought maybe if I temporarily grouped a freeform shape with a square, and applied the custom mold to the square, it might give the correct perspective, but no...

The attachment shows the creation of a custom mold in the shape of a measured perspective square (green), pasted on the target square (orange), which should have changed to recreate the shape of the custom mold, but it didn't (blue); so forget any controllable results with the custom perspective mold -- any other target shape will be nothing but wackier.

The custom mold doesn't give good results for three reasons that I can see:
1) The mold ignores foreshortening!
2) The mold conforms to a rectangular approximation of the object, instead of calculating from an absolute space squarely centered on the object.
3) As the stacked figures show, the resultant 'hello kitty?' shape continues the slope of the mold's top line, but translates the bottom line horizontally (marked in cyan). An algorithm based on Dig-Dug tunnelling from prison?

I'm disappointed, but my experiments show the so-called custom perspective molds are an exercise in wackyness and add nothing to the default perspective mold.

I've found the default perspective mold can in fact be used for controlled results if the object to be molded is first centered on an enveloping square and grouped, then the molded composit is stretched to conform to a known perspective square.

I would gladly purchase a usable perspective plug-in. And if anyone has any ideas about drawing in perspective with vectors, I'd like to hear them...

Ed Nadie

[gwpriester]

Hello Ned

Welcome to the Xara forum.

I'm afraid Xara's perspective envelope leaves a bit to be desired.

If you really want a first class perspective grid I recommend you try Macromedia Freehand 10. You can create your grid, adjust it as needed, and then snap your 2D objects onto the grid and move them about. As the objects move the perspective changes accordingly.

Xara is a much better application in many respects, but FreeHand's Perspective grid cannot be beat.

Gary

Gary Priester

Moderator Person

<a href="http://home.earthlink.net/~garypriester">
Be it ever so humble...</a>

[tonylondon]

The perspective envelopes are useful for creating a perspective grid which you can then use as a guide in the normal way. Attached is a xara file with the grids already produced for laying out with any desired vanishing point. You can go on to klone to make intermediate grids also if desired.
I would agree with Ed and Gary that the envelopes are not as clever as they might be. I do use them however. I set the object size with the stretch handles and then move the vanishing point rather than adjusting the four corners in order to get the shape right

Tony

[gwpriester]

Tony

Your file appears to be missing. I wonder if you ZIP it if it will download better?

Gary

Gary Priester

Moderator Person

<a href="http://home.earthlink.net/~garypriester">
Be it ever so humble...</a>

[tonylondon]

Thanks Gary,

heres a zipped attempt,

Tony