Y'all ready for an EXTREMELY THOROUGH OVERVIEW OF HOW TO DRAW REFLECTIONS IN MIRRORS USING PERSPECTIVE?

I'm sure you are.

This tutorial assumes a novice level understanding of perspective, such as knowing what a horizon and a vanishing point are.

Let's start with a mirror in one-point perspective. Easy enough. Draw a rectangle, using an arbitrary point on the horizon.

Objects and their reflections in mirrors are symmetric with the mirror in the center - that is to say, objects you see in the mirror will be as far away from the mirror as the mirror is from the object.

I've drawn in a space for what the mirror can "see", and then extended it into the mirror realm.

This space works like any standard space in perspective. I've drawn some, again arbitrary, lines extending to the same vanishing point I used for the mirror. Now... if I placed an object on one of those lines, how would I determine where in mirror space it's reflection is?

To do this we first need to determine the center of our mirror. Good news is there is a cool trick you can do with rectangles that you should always remember as it is very useful and is pretty much 99% of this entire tutorial.

Draw an X inside your rectangle. The center is where the lines cross.

You then sort of do the X trick again, but in reverse. You draw a line from where your lines intersect and make a diagonal through the center line you established in the previous step, to the reflected side of mirror space. You can then draw a new line from the vanishing point to this new mark.

Repeat as necessary.

Alright, tutorial over.

... just kidding.

I assume you now want to draw a box floating in your liminal space, so I'll go ahead and put one in for you. Mine is in perspective with the vanishing point, since it's easier.

So the cool thing about that box is that is doesn't well... exist in any defined sense.

Let me show you.

If I draw a line down and stop it in the back, it becomes big and distant (and not reflected in the mirror) whereas if I drop it into the mirror space it seems smaller and closer. Neat!

Ok so the box is floating in space now. We know that our mirror space is in one point perspective, so we ALSO know the box is going to be parallel to itself. But... how do we know how far to place it inside the mirrored area?

Well we could use what we learned before and figure it out using the spacing on the ground. If I drop the lines to where abouts I decide the box is hovering on the Z axis, I can use those X's and triangles to determine how deep the reflection appears. From here I can then draw the lines back up.

That way works well enough, but let's streamline the process a little. Why I do this will make more sense when we add more chaos later.

For now I've decided to place my box in space toward the edge of my mirror space, and drew some guidelines down and then up again at the mirror.

Now, since this is a nice friend shaped box I can just do the X trick again and determine my center line.

But I also want you to be aware that you can also determine the center line by cutting out a section of the mirror that matches the cube and bisecting it because the X trick is REALLY COOL.

Once you have where the centers meet determined, you can once again draw your lines through it to establish the matching points on the other side. Note that you'll need draw your lines back upwards again after crossing the mirror line. Why? For the same reason images are flipped in pinhole cameras.

I could go into detail about light, geometry, and cones, and photography but just... let it be known that it's flipped. You flipped it when you projected it, so you gotta unflip it.

Just go with it if this sounds confusing. Smile and nod.

From here you can draw your cube fairly normally. Bring out the line to find the other point and trace your lines to the vanishing point. And behold, the finished... uh, cube. Goodness he's a long boy.

BUT WAIT I'M NOT DONE.

But Scaz, you say, I don't want to draw a mirror in limited one point perspective, I want to draw that scene from Taxi Driver where he's saying "You talkin' to me?" which you will note has at least two points of perspective. At least.

Fine, but it gets more complicated from here on out, alright?

Add another vanishing point and GRANT YOUR MIRROR REALM INFINITE DEPTH.

From here you can guess what comes next, since this tutorial has more Xs than Scott Pilgrim.

Like a zen master, you must find your center.

And now you'll see it's more of the same, but instead of everything being in tidy parallel it's in chaotic receding triangles. That's fine, it still works the same. Use your center line to determine the matching mark and draw a line back through it to the mirror's vanishing point.

Note that you can do this in reverse, too. If you have an established line in the reflected side, you can of course draw it back forward through the mirror's center line to complete your X, even when the back has been been cut off.

Or you could expand your canvas but that sounds like effort.

Well, honestly from here you can pretty much use those Xs to flub most things. Draw in a little shadow, make sure it stays on the perspective lines. Most people would never know the difference.

... but what if I wanted to draw an arbitrarily twisting rhomboid prism floating in space, you ask?

I mean, preferably you don't.

But fine.

First you, like the cube (and again arbitrarily), determine where the thing is within the space, as suits whatever weird desires you have, and draw a line down.

I've chosen to place it in the mirror's vantage because otherwise this tutorial would be stupid.

Hilariously this new "center" is not precisely the mirror's center, but is darn close to it. Nothing left to do now but make it work and see it through.

Now before I dive right back into the rhomboid, I want to reestablish what I've been doing with these X's to determine where in space the reflection falls. I actually made a post about it the other day, which I'll quote now. But lemme explain.

Since I invoked it today, here is the art of measuring even distances in perspective.

This low key video offers a fantastic overview of it: https://www.youtube.com/watch?v=icSiKpK2ehQ

So basically the goal is to determine where on the other side of the mirror an object appears, yes?

We have already established previously that the object is equal distance from the mirror as its reflection is. So whatever X distance is, its the same. The trick is solving this problem in perspective, where its harder to determine what an equal space would actually look like.

Luckily people much smarter than me already figured this out. Probably Archimedes. Make a square and determine the center. I like to make one side the ground because it helps with visualization, but it doesn't matter. If this seems familiar its because we already did this in one point perspective.

You then essentially double the size of your rectangle by drawing a line from an outside corner, through the center at the edge, and to the "ground". You can use this to create the mirrored square. Or telephone poles or windows or whatever.

And here's the important part - it works in perspective.

Alright! Back to the rhomboid! Do you remember that guy?

Can you now guess what we plan to do here?

Draw a line from the point you want to mirror to the secondary vanishing point. You can already see the square taking shape, formed by the plane of the mirror and the line you dropped down to the ground as your guideline.

Put an X in it.

Draw a center line from the vanishing point through the cross of the X (or do it the other way I don't care I just find this way easier).

Then make a line from the point, through the center line of the box at the plane of the mirror, and to the ground on the bottom edge of the 2D pie slice

Draw this line up again, unless you want your reflection to be upside down.

Mark a spot where that line intersects the guideline drawn from the chosen point to the secondary vanishing point.

(This is of course that point you've chosen now reflected in the mirror)

OK, so now you just...

Repeat all the previous steps for the other points.

Now channel your inner kindergartner and play connect the dots. Try to remember with ones connect to which other ones so you don't scramble it up.

You now have mirrored the plane that faces the viewer.

Congratulations.

You may have noticed I haven't done the back half yet...

So what if your arbitrary hovering rhomboid prism's badonkadonk hangs outside of the mirror's vantage field?

Has complicated geometry and all our Xs failed us at last?

Of course not. Draw out the edges of the mirror back to the mirror's vanishing point. Then, as before, decide the depth, trace out your drop line, and take it to the secondary vanishing point. Where it meets the mirror plane, draw a line upwards - your new center line and the edge of your new box.

Repeat as before. Point to vanishing point, make X in box, line through X from vanishing point, line from point to ground line through the crossing of the mirror plane and the center line. Draw line up to top of the long box again, mark point of reflection.

Lather, rinse, repeat.

There's also probably a fourth point that isn't visible so I'm going to go ahead and add it...

here.

Good enough.

Connect the dots once more, referencing your previous guidelines if needed.

You have achieved... shape.

Clean off the edges outside of the mirror to obtain the illusion of reflected depth and admire your work.

What a shape.

(This is what happens when you pay little mind to your depth markers, I suppose. Maybe I should have gone a little bit less hard on the arbitrary.)

Thanks for joining me on this adventure.

As a reward, you can have some MIRROR FUN FACTS!

1. You cannot touch your own reflection in most standard mirrors - they are made with a reflective surface applied to the back of a pane of glass, which serves as a barrier between you and your mirror self.

2. No matter how far (or close) to a mirror you stand, from your perspective your body will always occupy the same volume of the mirrors surface! Geometry is cursed!

3. There is such a thing as a "true" mirror. It shows your image as other people see it, rather than horizontally reversed as with a traditional mirror. Apparently the effect is surprisingly dramatic to observe. See it here:

https://www.youtube.com/watch?v=2Lyc6DJ69To

If you have any questions (on this topic or anything else) feel free to drop me a message on Bluesky!

Thanks for reading!

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