Rubber Vector

category: code [glöplog]
That´s not "per scanline" ;)
In Raymarching "per scanline" would be rotating using fragCoord.y (UV.y)
You are rotating in object-space using ray-positions y-coordinate! While object-space is the same as world-space in your case, as you didn´t translate or manipulate your object in other ways before rotating it.
Sorry, didn´t want to let you look dumb or anything, but i guess this could confuse people if not clarified!
and just as a bonus information about different spaces in graphics:
fragCoord (UV) is screen-space
No worries, thank you for the correction, and explanation. I have very little experience with shadertoy, and raymarching. So basicly i am dumb on the subject and anything helps me to gain a better understanding.
added on the 2018-05-20 09:49:46 by SCA SCA
I adapted the code to now use uv.y
Would it be more correct "per scanline" now?
added on the 2018-05-20 09:59:56 by SCA SCA
yes, if you want to let it look "oldskoolish" for sure!
but nowadays i would go with the object-space-rotation you had before...looks better in my eyes! also it´s a bit hard to rotate screen-space for one object only! ;)
Hello everybody.
I have some problems with displaying my rubber vector: how to avoid this bug (discontinuity at the bottom of the vector)?

I display it by displaying lines of next frames.

BB Image

Please help!
added on the 2018-10-30 15:25:10 by UnlkA0 UnlkA0
Isn't that just because you rotate it too fast?
added on the 2018-10-30 15:44:01 by Gargaj Gargaj
On the linked picture, there is a rotation of 1 degree at each line. If I make a rotation of 0.5 degree at each line, the bug disappears. So you're right.

But when I watch Octorubber by Blueberry, his vector has a wide twisting, so I guess more than 1 degree of rotation at each line.

Maybe I'm wrong or missing something?
added on the 2018-10-30 15:58:35 by UnlkA0 UnlkA0
So nobody has an idea?

Blueberry, Slummy, Paradroid, are you here??? :)
added on the 2018-10-31 09:06:01 by UnlkA0 UnlkA0
It's hard to say from an unshaded still image, but my guess is that it is not a bug. It just so happens that the scanlines rendered with different time offsets create that shape.

In Octorubber, the time shift propagates at 200 scanlines per second, so 1 degree rotation per scanline would mean a full rotation in less than 2 seconds. I don't think it rotates that fast.

Even then, if you step through the youtube, you will see some frames here and there with artifacts very similar to the one in your picture.
added on the 2018-11-02 16:24:37 by Blueberry Blueberry
Yepp, pretty much the same conclusion here :)
Could it be related to rounding errors? What happens if you rotate 0.5 degrees twice? Same exact result, or slightly different?
added on the 2018-11-02 17:37:18 by yzi yzi
Thanks you for the answer! As I wrote on ADA forum, now it works fine. As you said, I rotated each frame too much.
added on the 2018-11-10 21:24:53 by UnlkA0 UnlkA0