Another Method for doing Isometrics?

[JSC]

Can you draw walls, doors, windows,  curved, and circular openings on a "normal" grid, then group all if them, change to Isometric grid, then scale/skew the group and snap to the iso grid?

 

Might this be easier for some people when attempting to draw vertical surfaces from looking at an architectural elevation or section?

[JSC]

up

[JET_Affinity]

Sure, you can do that in most any drawing program, even without a grid. But understand, if you are coming from previous experience with the similar grids feature in Serif DrawPlus, Affinity's feature is not (yet) as functional. For example, in Draw Plus, "projecting" artwork drawn "in the flat" onto one of the grid planes is automated. In Affinity, you have to do it manually.

Example:

1. Draw a regular orthographic elevation of a wall, with whatever details you desire (curved windows, etc. etc.)

2. Select everything. Group.

3. Transform Panel: Rotate the Group 45 degrees.

4. Context Toolbar: Click the Reset Selection Box button.

5. Transform Panel: Make sure the chain link between the H and W fields is off. In the H field, key in "*.5774" (asterisk followed by .5774). Tap Enter.

6. Transform Panel: Enter -30 in the R field.

Now go to View: Grid and Axis Manager and specify the isometric grid with Create Plane Set turned on. Close the dialog. Tap the apostrophe key twice to toggle to the vertical left plane's grid. You will see that the drawing is skewed to be parallel to that grid. Moreover, its width will also be correctly proportional to its height. You can drag the drawing around and snap it to the grid increments (assuming you have Snap To Grid turned on, of course).

Ungroup the drawing and you will see that the bounding boxes of the individual paths are also skewed and scaled, allowing you to drag their side handles to scale the objects parallel to the grid.

Alternatively, you can:

1. Draw the same elevation in regular orthographic view. Group it.
2. Set up the isometric grid. Toggle to the left or right vertical plane grid.
3. Drag the group to snap one of its bottom corners to an intersection of the grid.
4. Skew the group vertically, snapping its bottom edge to the grid's "horizontal".

Just realize that merely skewing the elevation results in its width being out of proportion. (The wall will be short and squat.) You also have to scale it horizontally.

That's the basic idea. Of course, you need to set up the spacing of the grid to correspond to the unit of measure at the scale you are using. (Otherwise, the grid is usesless as a measuring device.)

Drawing "boxy" surfaces like this (even when including curves in the artwork of any shape) is rather trivial. You really don't even need a grid to do it.

Again, comparing to DrawPlus: DrawPlus can actually not only automate sending objects to one of the axonometric surfaces, but that actual assignment becomes an attribute of the object, unless and until you release it from the plane, and it returns to its orthographic shape. Affinity's feature has none of that functionality (yet; I hope the full functionality is in the plans). But the grid in Affinity can be handy as a snapping and measuring aid.

Just be aware that no measures in axonometric (isometric, dimetric, trimetric) drawing are arbitrary. They must all be in correct proportion; otherwise, you're not drawing axonometrically, but just creating some randomly skewed oblique. In Affinity, that means you have to be sure all three of the spacing values of the three perpendicular grids are in correct proportion. Affinity doesn't automatically ensure that for you, except in its isometric setting. (Isometric, by definition, uses the same measuring scale along all three axes.)

JET

[Alfred]

5. Transform Panel: Make sure the chain link between the H and W fields is off. In the H field, key in "*.5774" (asterisk followed by .5774). Tap Enter.

 

Alternatively, key in *tan(30) and let Affinity perform the trig calculation for you. ;)

[JSC]

Thanks folks for your input.  I have a lot to learn about Affinity's capabiliities/functions.  

This is the first 2D app I've used (coming from CorelDRAW and Xara) where you can enter function notations directly (v.s. using a script/marcro).  

 

 

 

"3. Transform Panel: Rotate the Group 45 degrees"

Is this so that the position of the nodes of  circular geometry align to grid properly?

[JET_Affinity]

"3. Transform Panel: Rotate the Group 45 degrees"

Is this so that the position of the nodes of  circular geometry align to grid properly?

 

The 45 degree rotation is so that the foreshortening of the width and height of your elevation drawing automatically end up foreshortened in correct proportion to each other when you perform step 5. (In the case of isometric, that proportion would be 1:1; both width and height must be foreshortened by the same factor.)

 

In isometric drawing, all three perpendicular axes are measured by the same scale (foreshortened equally). That means that the three visible perpendicular sides of an object (oriented parallel to the axes), are viewed from the same angle, relative to the line-of-sight.

 

Imagine a box and you're looking "straight on" at one of its sides. Your elevation has been drawn on the top of the box, but you can't see it from this viewpoint. So first, you rotate the box about its vertical center so that its two visible sides make an equal angle with your line-of-sight. Since the box's sides make right angles with each other, that means that you rotate the box 45 degrees. Let's call this the "front view" of the rotated box. You still can't see the top of the box from this view, but you can see two of the sides, and they both make the same angle (45 degrees) with your line-of-sight.

 

Now you want to tilt the back of the box upward so that you can see the top of it (and thereby see your elevation drawing), but only just enough that the top of the box ends up making the same angle with your line-of-sight as the other two sides. Geometry dictates that amount of tilt must be 35 degrees, 16 minutes; the so-called "isometric angle." (Approximately--the actual value is the arcsine of the tangent of 30°, which is 35.264389682754654315377000330019 degrees at 30 decimal places. But you'll be forgiven--even by Alfred--for not splitting such fine hairs. ;-)

 

So think of the steps in my previous post as sort of the reverse of that process. In step 1, you drew the elevation on top of an invisible box. In step 3, you rotated that box 45 degrees about its vertical axis. In step 5, you effectively "tilted" the box 35 degrees, 16 minutes by scaling it vertically by the sine of the isometric angle (.5774), or 57.74% if scaling by percentage as in other programs.  That's the geometric basis of isometric drawing. The result of isometric drawing is actually an orthographic projection of objects in a coordinate system rotated and tilted just so.

 

If you are familiar with common drafting ellipse templates, you are aware that they are labeled in degrees (10 degrees, 20 degrees, etc.) Let's take 60 degrees as an example. A 60 degree ellipse template represents a circle which has been viewed edge on, and then "tilted" upward 60 degrees.

 

But in Bezier-based mainstream drawing software, ellipses are usually defined not by degrees, but in terms of major and minor diameters (width and height). You would create a 60 degree ellipse by drawing a circle and then scaling it vertically by the sine of 60 degrees.

 

Same principle applies with isometric ellipse templates. That's why isometric ellipse templates are labeled 35 degrees, 16 minutes. You can draw an isometric ellipse by drawing a circle and scaling it vertically by the sine of that angle. Well, if that circle happened to have other details drawn inside it or even outside it; the same transformation would effectively "tilt" all those details in the same way. That's what you did with your elevation drawing. Then, in step 6, you just rotated the "whole drawing" as if to "lay the invisible rectangle on one of its sides" so that the elevation drawing is now on one of the vertical sides, rather than on the top. Just assume the invisible box did not have "This Side Up" painted on the side. ;-)

 

JET

[Alfred]

Now you want to tilt the back of the box upward so that you can see the top of it (and thereby see your elevation drawing), but only just enough that the top of the box ends up making the same angle with your line-of-sight as the other two sides. Geometry dictates that amount of tilt must be 35 degrees, 16 minutes; the so-called "isometric angle." (Approximately--the actual value is the arcsine of the tangent of 30°, which is 35.264389682754654315377000330019 degrees at 30 decimal places. But you'll be forgiven--even by Alfred--for not splitting such fine hairs. ;-)