Spherical Raster

Category: Unknown · Tags: cadet · Posts: 11

#1 — jestern · 2020-11-29

HI all, sorry I have lots of questions in this period. I’d like to transform my raster into a spheric one. I have the formulas tested. I need two quadrature oscillators and three multipliers. One of the quadrature oscillators has to be for the Vertical dimension and one for the Horizontal thus fast. Is there a circuit that can do that? I basically have to transform polar into cartesian coordinates. And provide radius and 2 angles. I need two polar to cartesian converters and they use quadrature. Any help?

#2 — VisibleSignals · 2020-11-29

This is my holy grail! Analog rotation is very difficult.

I learnt about “Bhaskara I” the other day (which I think is amazeballs) but it’s still only a very small part of the puzzle. Stock up on a whole pile of LT1256 for those multiplication operations!

#3 — jestern · 2020-11-29

Did not know about Bhaskara I. I’m sure it’s possible, my problem is that fast quadrature circuit. I have a circular sweep maybe that’s enough.

#4 — rempesm · 2020-11-30

Mapper gives you sine/cosin out on its U/V outputs.

#5 — Rik_bS · 2020-11-30

I don’t need to know this, just need to wait for the Chromagnon, but damn that is a handy piece of info to be aware of in case I see a mapper for sale

#6 — jestern · 2020-11-30

hey that’s amazing I’ll look into that.

#7 — rempesm · 2020-12-01

Would you mind sharing your formula for this? I think I’ve finally got 2D rotation down from the formula

x * cosine - y * sine>>>> x * sine + y * cosine

and would love to figure other ones out. I need to post my mostly Cadet patch for that, too.

#8 — VisibleSignals · 2020-12-01

That’s rotation around (0,0) so you probably need to think about axis shifting as well.

#9 — jestern · 2020-12-01

The formula I have it’s in Max/MSP but basically requires two rotations, one of 360 and one of 180. I usually take horizontal 360 and 180 vertical. What I use there is two polar2cartesian converters. So I input radius and angle and get X and Y. It’s rather easy formula of course 1. x = r × cos( θ ) 2. y = r × sin( θ ) and 1. x = r × cos( phi ) 2. y = r × sin( phi ) what you need though is a Sine Cos VCO at H and V rate. The V could be a LFO theoretically and the Vertical could be the Mapper I think. Phi and Theta are your ramps scaled to fit 180 and 360 degrees in whatever scale it is. I’m thinking whether to buy a Mapper or getting a Chormagnon which costs basically double but gives me other things to do. I have no clue what the Chromagnon does and maybe it’s overkill for me. I have my own laser patch system, so don’t need that and I don’t do color video, I like monochromatic. So I wonder if I better stay with the Mapper. Difficult to know until I see some use of it. Maybe I’ll ask Derek or Lars …

#10 — Robbertunist · 2020-12-01

For those like myself not familiar with some of the terminology found in these equations, this video covers some of the fundamentals & I found it very helpful.

https://www.youtube.com/watch?v=9UBdqqStmDg

#11 — Robbertunist · 2020-12-01

I’d love to see your Cadet patch for rotating ramps @rempesm

I thought I had previously seen some patch notes & screenshots in a thread that included mostly cadet modules but I must be mistaken or simply can’t find out in the search.

The link below is to a thread that’s really helpfully to build an understanding as to what exactly the shapechanger & navigator are doing to rotate ramps and also how combined pairs of the arch & staircase modules can achieve the same results.>> Another cross post from Facebook. This was a question i had been looking for a answer to recently. >> Zach Michels - If I had a Navigator, could I spin shapes I am making in Cortex from Cortex ramps? Most of the videos I see with Navigator are doing exciting things, but I don’t feel like I’ve seen examples of this. I understand that with the release of Shapechanger this will be possible, right? Any one who has a Navigator wanna make an example video? > Cheers all. >>> Lars Larsen - The missing ingr…>