Topic: Analog laser shunt modulation

[James]

That's a good point!

The next vertex you need to look at is usually either the one just before or just after the one you are looking at now.

Plus, inserting a new vertex between two that already exist is way faster with a list.

James. 

[dtewksbury]

Yes exactly, and the advantages outweigh the disadvantages. Plus the other cool thing is that I have a function that is called to get the next vertex, but that is called from a function that does all of the ballistic calculations (extra vertices between points etc), and that counts the PCM samples that are created to go to the DACs, and sends this value to the animator, but only at the frame boundaries. So this means that as the image is animating it is dynamically adding and removing extra vertices depending on the distance between the original vertices which changes during the animation. So the animation speeds are consistent, although the frame rate is constantly changing, but the images are consistently nice.

Daryl.

[dtewksbury]

Hey James, by the way I notice you are using SDL, I started using that a when I began writing graphics applications. I tried to use DirectX after that but found it too confusing. I now use OpenGL, it is simple to use and has similar performance. For any audio I use FMod, but I have designed all of the hardware for this project and don't use any windows drivers for any of it. In fact the only library I use is the OpenGL one. Everything else has been written by me.

So like your application, mine doesn't rely on any big bloated Microsoft libraries to be installed, I can just copy the executable and opengl dlls and it runs, no installation, very portable. All the networking sections I use Winsock and that's built into the OS, all my networking is UDP, I have written all of the libraries to handle dropped packet recovery etc, so it works well over a wireless connection as well.

Daryl.

[drlava]

yeah, I saw that blanking retrace pop up, but as you said it's an easy fix not worth mentioning.  I noticed the scan rate for the text changing as you scaled it, also.  Have you tried scanning with and without this feature?  The goal is to have the scaling not create changing artifacts as more points are added, in some cases scanning artifacts, if they exist, are more tolerable if the don't change as the frames are scaled and manipulated in 3D.

PCM samples, eh?  Are you using high end audio D/As for output? Leverage some good existing tech if you are!

[dtewksbury]

Hi drlava, yes I am using the 24 bit Alesis DACs (I have ADAT compatibility, with optical IO for our old stuff). I have found these DACs to be awesome. I use them for position and color. At the moment I have 6 channel color and two scanner sets out for each laser, but I am decreasing that to 4 channels of color and one scanner set per output. This is because we have a lot of mixed gas lasers that use PCAOMs, we are phasing these out and going OPSL, hence the hardware changes.

I have designed all of the analog section on the output which is all DC coupled of course.

As for your other question, it is easy to disable the auto point calculations, or change it on the fly, all of the settings for this can be adjusted/disabled on a per image basis, because some images need different processing. However I have found that if you do that the start and end points can get a bit ugly where there are large traversal distances, so I leave it on most of the time. It is only really an issue when trying to video it. It is made worse by the fact that the camera is interlaced, I will eventually get a HD camera with adjustable frame rate to get better captures.

Also it works well to give consistent brightness to images that come to the front and go to the back, or get large and small if you like.

[James]

Right now it's about 0°C in Akron, Ohio.

Or it that -0°C ?

James.   

[dtewksbury]

Wow, it is 34 Deg C here at the moment, and it will be 40 tomorrow.

[James]

There's an old saying around here.

If you don't like the weather in Ohio, just wait a few minutes.

I've seen it go from below freezing to 65°F in half a day.

James. 

[BlinkenLights]

thats an old saying about Maryland too.. and since maryland is older i think you stole it from us.