Hello everybody,

I'm fairly new to isadora, and I'm having a lot of fun with this new tool. But I cannot understand how 3D projection is dealing with distance.

For context, I have numerous little screens with various resolutions (the scenery I'm projecting onto is a wall of frames), and I want to use 3d projection to do 3d spinning effects. Sofar so good.

But my problem is to compute the required z translate for a video to make the video stream fullscreen. I want to compute it from input ratio because I have more than 30 frames with almost as many ratios and fine tuning by hand is gonna be a pain.

I've read this, which is closely related : https://community.troikatronix... but I'm not really satisfied with the answer... I mean, all the context is great, but it doesn't seem to me that the image is rendered on a cardboard of 1.000 x 1.777 Units for a 16:9 stream. Or if so, I suck at math much worse than I thought. (this is the best explaination I could find about the math https://gamedev.stackexchange....)

Anyway, I have another problem that fried my brain even more : If I use a 3D projector or a normal projector with 3D mode enable, different z translate values are required to make the image appear the same size. So I tried many resolution, manually changing z translate to fit and many calculations to try to "reverse ingeneering" but I cannot make sense of theses values at all.

So, basically, can somebody explain what's the units we are dealing with here ? When the image is rendered in 3D space, what "real" size is given to the frame ? Or if it's really that the width is always 1.000 unit as @mark suggests in his answer, can anybody give me the math to compute this -2.75 from a 16:9 ratio (or around -1.56 if 3D projector is used)

Here is my patch where I try to figure this out. Basically, I would like the JavaScript box to output the z translate value.

This has been bugging my brain for the last 3 nights, so any help would be really, really appreciated ;-)

[and happy to be part of the isadora gang now]