Split shear/skew function into H° and V° fields

[cchris]

Unless I'm missing it, there's no way to shear/skew a shape with independent horizontal and vertical values. I need that function to do isometric drawings, so please consider adding it to the next update.

 

Attached is a procedure we use to teach new writers how to create isometric images (using FreeHand so it's ancient).

 

Thanks,

Chris

Guide to isometric.pdf

[Ben]

Unfortunately, our transforms are expressed in a fixed order, where the rotation is taken into account before the skew.  If we added vertical skew, it would always revert to '0' in the transform panel, as the component would instead be expressed as rotation and horizontal skew.

 

Effectively, that means that to achieve a vertical skew, as in the isometric guide, you have to skew horizontally, then rotate.

 

You can actually achieve the result using our isometric grid and snapping.  Drag the skew control on the vertical edge of a box, and you can snap it to the isometric grid lines.

 

There will be additional tools coming in the future to help you snap objects into the isometric grid, and to create new shapes on an isometric plane.

 

You could also use these values for your transform for isometrics:

 

Right face: Rot 30, Skew -30

Left face: Rot -30, Skew 30

Top face: Rot 30, Skew 30 or Rot -30, Skew -30

[Andy Somerfield]

It's also worth noting that this is a limitation of affine homography generally - there is actually no such thing as "Skew" - only a rotation followed by a scale, etc.

 

That doesn't mean we couldn't expose a vertical shear component - but it would reset to 0 after each application (as Ben has stated). If this would be of use, it can certainly be considered..

 

Thanks,

 

Andy

[cchris]

Thanks for the quick replies!

 

The problem is that you don't quite get true isometric images with the rotate and shear method, as shown in the attached Test image. The Designer image was so distorted that I think you must have meant using the rotate/shear in the same way Adobe Illustrator does it (see attached).

 

But the Illustrator version is incorrect in the horizontal dimension. The FreeHand version is much more correct.

 

 

isometric_long2.afdesign

Test.afdesign

[Ben]

As I said - I'll be adding tools to help convert or create shapes to isometric grid (or other grids).  I'll try and figure out a way of including projection proportions for the planes for when you convert a 'flat' shape to a plane.

 

I imagine a quick function to convert a 2D shape/object to one of the three planes would be handy, doing the transform for you in one go.  This would also enable you to transform embedded documents to plane.

 

If you enable "Create plane set" with an isometric grid, you'll be able to cycle through the planes with the ' key.

[Ben]

Thanks for the quick replies!

 

The problem is that you don't quite get true isometric images with the rotate and shear method, as shown in the attached Test image. The Designer image was so distorted that I think you must have meant using the rotate/shear in the same way Adobe Illustrator does it (see attached).

 

But the Illustrator version is incorrect in the horizontal dimension. The FreeHand version is much more correct.

 

Really?  To me the Illustrator one has the correct proportions, and the Freehand one looks wrong.

 

For isometric, all three edges of the cube should be the same length.  This would make the Freehand too short in the vertical dimension for the side faces (about 0.86, which is what you need to scale the height by after rotate and skew).  As I understood it, Isometric is not a proportional projection like Trimetric.

[cchris]

Really?  To me the Illustrator one has the correct proportions, and the Freehand one looks wrong.

 

For isometric, all three edges of the cube should be the same length.  This would make the Freehand too short in the vertical dimension for the side faces (about 0.86, which is what you need to scale the height by after rotate and skew).  As I understood it, Isometric is not a proportional projection like Trimetric.

 

I'm confused by your reply because the FreeHand version of the isometric is the only one of the three versions that has the same height and width as the original 2D drawing. The Illustrator version is too narrow in width, and the Designer is way off.

[Ben]

If you measure the edges of the cube drawn in the Illustrator example (post transformation), you'll see that they are all the same length.  That, to me, is correct isometric ratio.

 

On the freehand one, the vertical is 0.86 (square root of 0.75 to be precise) the length of the two diagonals. That's why it looks squashed vertically.  It's not a pleasing cube if intended to be a parallel projection from the isometric view point.

 

Remember that isometric drawing was originally done on equilateral triangular grids.  To try this - use our Triangular grid (instead of Isometric), and you'll see exactly what I mean.

 

 

The grey cube, above, I drew the three faces using the pen tool and our Triangular grid.

[cchris]

If you measure the edges of the cube drawn in the Illustrator example (post transformation), you'll see that they are all the same length.  That, to me, is correct isometric ratio.

 

On the freehand one, the vertical is 0.86 (square root of 0.75 to be precise) the length of the two diagonals. That's why it looks squashed vertically.  It's not a pleasing cube if intended to be a parallel projection from the isometric view point.

 

Remember that isometric drawing was originally done on equilateral triangular grids.  To try this - use our Triangular grid (instead of Isometric), and you'll see exactly what I mean.

 

isometric.png

 

The grey cube, above, I drew the three faces using the pen tool and our Triangular grid.

I see; thanks for explaining it. 

[Ben]

1.7 will include some new tools to help with isometric and parallel perspective drawing.

 

FastIsometric.mov

 

More to follow....