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Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
"Wow, it's so pretty - I don't suppose you could also release a dedicated standalone version? XD -Emanuel The standalone is used to test and design the screensaver routines very quickly and it is easily made available, so the demo being released could be called the standalone version. "It seems you try to display a lot of points (stars). I guess many of them will be very close (at lest on the screen). Would it be possible to reduce the data to display by some kind of "abstraction" ? Maybe you can select only some representatives of the whole star dataset, based on distances to each other. Another idea would be to "merge" several stars together, and replace them by one star with an "averaged" position and brightness. What do you think? - Frankm Absolutely! I have been kicking this idea around since the start of the project, but there are a few issues. The stars could be cut up into sections and averaged by using an inverse tree. This is similar to what is done when rendering textures at further distances. This tends to create a flickering effect during the transition that I considered undesirable for the screensaver. It could be overcome completely by waiting until stars were less than an 8th of a pixel apart to use their average. This did not seem necessary for the screensaver as it is now, but this mehthod would be critical for a larger-scale application using millions of stars and a larger range of distances. "About the ATI GPU version: I have a relatively fast ATI Mobile HD 5850 in my new laptop, - Frankm We are working on a way to do that for the N-Body computations. It is too early to say for sure at the moment, but one idea was to split up each double precision value needed into three or four floating point operations. It would be slower than direct float-based math, but potentially useful if it allowed full use of the GPU. Edit: this idea would actually produce slower results than not using the GPU on closer inspection. Matt A. and Ben have told me that the N-body will rely on double-precision math as well. The screensaver could benefit from using single precision enhancements, but this would most likely be implemented in later versions. "The wedge on the preview screenshot basicially looks like a slice moving in 3D. Maybe you could use a 2D surface to render the wedge into, and then let OpenGL project the data onto the "slice" in 3D?" -Frankm That is clever. I hadn't thought of it. It would produce flattening and make the wedge invisible from certain angles, but other angles could potentially get a boost in speed. The library already uses textures for the individual stars so it is hard to say how much faster it would be without testing. Open-GL might be able to accelerate the current star draws as well, but CPU code was chosen for maximum compatibility in this revision and also because there does not seem to be native GPU support for pixel-summing with textures. This might require GPU programming. |
Send message Joined: 8 May 10 Posts: 576 Credit: 15,979,383 RAC: 0 |
I think that card should support doubles. Nearly all of the 5xxx series do, except randomly a couple don't. |
Send message Joined: 4 Jun 09 Posts: 45 Credit: 447,355 RAC: 0 |
I have a question that didn't hit me till now.. Most screensavers for BOINC projects only keep showing till the current WU is finished ..then the screensaver goes away when the new WU starts crunching..what will happen if a GPU user opens up the screensaver being that it only takes me about 1:14mins to complete 1 WU? |
Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
Most screensavers for BOINC projects only keep showing till the current WU is finished ..then the screensaver goes away when the new WU starts crunching..what will happen if a GPU user opens up the screensaver being that it only takes me about 1:14mins to complete 1 WU? -ztmike That's interesting. BOINC controls screensaver activation and resource use. It may automatically terminate a screensaver under certain circumstances. If it does terminate the screensaver early, it is something I could discuss it with the BOINC team since it would be highly undesirable. I would consider it a bug. Please feel free to let me know if this happens after the initial release. |
Send message Joined: 17 Nov 08 Posts: 9 Credit: 20,001 RAC: 0 |
Maybe it would help to look at the "abstraction" problem from the astrophysics point of view? You could merge stars based on their distance and mass/brightness once, and then use this abstracted dataset for the screensaver. If you are already looking at N-Body simulations, you could possibly re-use a spatial tree representation (like a barnes-hutt octtree); the end nodes of such a tree could be candidates for merging. Would it be possible to allow the user to control the amount of abstraction? best regards, Frank
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Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
"Maybe it would help to look at the "abstraction" problem from the astrophysics point of view? You could merge stars based on their distance and mass/brightness once, and then use this abstracted dataset for the screensaver. If you are already looking at N-Body simulations, you could possibly re-use a spatial tree representation (like a barnes-hutt octtree); the end nodes of such a tree could be candidates for merging. Would it be possible to allow the user to control the amount of abstraction?" -Frank That is an interesting idea, and a commonly used one for physics approximations. Some physics team members of the MilkyWay@Home team suggested as you did to merge stars, while the computer science members tended to suggested skipping stars (I had the same idea). I tried skipping stars, however it became impossible to see the density distributions without increasing the size of the blurs. Losing the over-densities is undesirable since the point of the separation research is to match them to the stream. Increasing the size of the blurs creates similar overhead and makes things look "fuzzy" as one user pointed out which many people have indicated is also undesirable. User control is simple to implement for any features you would like to recommend, either through an 'ini' file or through the use of function keys. |
Send message Joined: 12 Aug 08 Posts: 253 Credit: 275,593,872 RAC: 0 |
An other vote for color.
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Send message Joined: 17 Nov 08 Posts: 9 Credit: 20,001 RAC: 0 |
I just looked up the specs on the ATI website. It seems that most of the newer cards support doubles, except for the Mobility cards. In a knowledge base article (http://developer.amd.com/support/KnowledgeBase/Lists/KnowledgeBase/DispForm.aspx?ID=88) they state that only the Mobility Radeon HD 4800 Series supports doubles. Mobility Radeon HD 5850: # TDP: 30-39 Watts (GDDR5) or 31 Watts (GDDR3/DDR3) # Engine clock speed: 500-625 MHz # Memory bandwidth: 64 GB/sec (GDDR5) or 28.8 GB/sec (GDDR3/DDR3) # Polygon throughput: 500-625M polygons/sec # Processing power (single precision): 0.8-1.0 TeraFLOPS (and no double precision...) Radeon HD 5850: # Maximum board power: 151 Watts; Idle board power: 27 Watts # Engine clock speed: 725 MHz # Memory bandwidth: 128 GB/sec # Polygon throughput: 725M polygons/sec # Processing power (single precision): 2.09 TeraFLOPS # Processing power (double precision): 418 GigaFLOPS |
Send message Joined: 27 Nov 09 Posts: 108 Credit: 430,760,953 RAC: 0 |
...they state that only the Mobility Radeon HD 4800 Series supports doubles.Yet they claim 128-bit precision on all operations on, say, the 530V line. Why bother? |
Send message Joined: 9 Feb 09 Posts: 166 Credit: 27,520,813 RAC: 0 |
First on topic another vote for color now offtopic: ofcourse not many mobility videocards support double precision.. the whole purpose of these cards is trying to give a good output with minimal heat and power draw ... lol what you think double precision do ;), mw is a super way to heat up your videocard and if its a laptop get it to shutdown because gets overheated xD All normal HD 5850 support double precision only the lower models seem to lack this but its sometimes hard to find if they support it or not I think the rule in this case is when they not mention it on the specs it probably is not implemented Its new, its relative fast... my new bicycle |
Send message Joined: 4 Jun 09 Posts: 45 Credit: 447,355 RAC: 0 |
I see its been 32 days since last reply..any updates on the screensaver release? |
Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
I am back on the project after being unexpectedly pulled away on personal business for some time. Demos will be released in the next few weeks. Testing is needed for all platforms before the first release. If you would like to test a quick demo to see if the application will run on your machine, feel free to try this and post your results (and specs if applicable): http://www.rpi.edu/~reills2/mwdemo/ (Windows - all versions) Usage: < / > - Move in / out F1-F9 - Change speed Arrow - look around Ctrl-arrow - spin view Shift-arrow - rotate object Tab - Start over You should see a blue blinking cube for the test. |
Send message Joined: 18 Nov 07 Posts: 18 Credit: 38,429,435 RAC: 0 |
I see multiple blue dots in almost all views but none look like a cube. Intel q6600 quad, Asus p5k deluxe, 3 gig ddr ram, 4850 ATI video. "There is no limit to the amount of good a person can do if they do not care who gets credit for it." |
Send message Joined: 18 Nov 07 Posts: 280 Credit: 2,442,757 RAC: 0 |
Indeed, lots of pretty blue bubbly things fading in and out. They sort of form a cube together, but not really. I also managed to break it at some point - pressed > and everything went black aside from the axes at the top. |
Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
Thank you for the feedback. I would be especially interested in computers that do not show anything, but feel free to comment on working runs as well. You can press |
Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
Here are two new versions of the test in a zip file. Just extract the file to your desktop (or anywhere else you prefer) and run the two application files. Both files are the same program, but one runs in full-screen mode. If "cube_test.exe" runs on your machine, try the full screen version. As a precaution, it may be wise to close other applications and save work before running the full-screen test. For those that are not running Windows XP or later, downloading an application such as 7-zip or WinZip will allow you to extract zip files. cube_test_win.zip Usage: < / > - Move in / out F1-F9 - Change speed Arrow - look around Ctrl-arrow - spin view Shift-arrow - rotate object Tab - Start over Backspace - focus on center of cube Edit: Space to stop motion Yous should see an arrangement of glowing blurry stars in a cube formation as you zoom out. Speed Please post results of the test and specs if the applications did not run properly if you would like to contribute to the screensaver testing. Tests with the stand-galaxy simulation will also be available soon. |
Send message Joined: 18 Nov 07 Posts: 280 Credit: 2,442,757 RAC: 0 |
Wow, it's so psychedelic. Took me a while to figure out how to get it to work. The F keys only take effect once you actually press > or <, and once they do you can't stop it, only go faster or slower and switch between zooming in and out. F5 is a bit too fast for me, I'd recommend F4 (is this dependent on the speed of your PC?). It sort of ends up like an angry white blob - is that intended? The blue edges seem to be divided into two bands instead of a smooth transition, but maybe that's just how it works. |
Send message Joined: 2 May 10 Posts: 57 Credit: 2,138 RAC: 0 |
I have added a note that the spacebar will stop the camera motion. Thank you for pointing that out. |
Send message Joined: 18 Nov 07 Posts: 18 Credit: 38,429,435 RAC: 0 |
Ok got to the cube but my in out controls are < (out) > (in) Out meaning the cube gets smaller or further away and in means the cube goes to individual dots. Also the arrows move the cube opposite the arrow,,,,,, "There is no limit to the amount of good a person can do if they do not care who gets credit for it." |
Send message Joined: 19 Feb 08 Posts: 350 Credit: 141,284,369 RAC: 0 |
Sorry, my in/out controls </> do not work. Maybe because of german keyboard layout? |
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