Led Blur demo (GP32/PC)

[Optimus]

This is a preview of my long awaited Led Blur demo!



It's some effects I started developing for the GamePark32 handheld console (ARM at 66Mhz overclocked till 133Mhz or more, 8MB Ram, no FPU, 320*240*8/16bpp modes). I was lent this handheld the last summer and I should be producing a demo for it. I hope to finish my demo inside July, things didn't went as I wished. The good news is that a PC port of the demo will be released too. And here is the preview running on the PC port code (C and SDL). My 1st software 3d engine and few 2d effects, some of them you might have seen in my older demos, anyways I plan to combine 3d and 2d together, to make more complex screens than those pure effect examples. Enjoy and leave your comments here!

http://optimus.demoscene.gr/previews/ledblur_preview.zip

[Stonemonkey]

Great stuff, love that water effect.

[Ghost^BHT]

cool effects and that you included a pic of my wife(in the water effect) is a bonus Can't wait to see the final version.   

[relsoft]

Cool!!! Screenies!!!!

GP32. Isn't that a handheld console?

Cooler!!!

I could only see the juila animator though. :*(

[Stonemonkey]

I didn't quite get it at firsteither relsoft but use the L and R keys to change to a different effect.

[Clyde]

Thats real cool Optimus Dude, I'd love to be able to do effects like those, and others from your past releases. Mostly, the swirling colour effects.

Nice one, and all the best with it's progress dude,

Cheers,
Clyde.

[Shockwave]

Nice effects, especially the water effect, the fractals and the envmapped head.
Colours were a little strange but it all ran real nice and fast, around about 124fps here with no slow down at all and no glitches.

P4 3.0ghz, Radeon X300 se 128mb , 512 mb.

Thanks for posting it 

[Shockwave]

The other thing is the cube with the affine mapping, the texture warps a little. You could fix it easily by cheating;
Subdivide the faces into say 9 squares each so that the perspective has less effect and the textures don't warp as much..

Or use the perspective correction formula, instead of interpolating U,V, interpolate U/Z, V/Z and 1/Z and at each pixel divide the texture co-ordinates by Z.

[Optimus]

Thanks! Colors are not as they would look in GP32. They appear a bit darker there and you won't see that greenish light in the tunnel part for example, nor the pinkish envmap. Unfortunatelly, everything appears darker in GP32, when I upload images for the image viewer app, I first set their gama to x2 to see them properly and still the colors change. So, before releasing the PC port of the final demo, I'll have to darken the colors for it..

And yes, use L/R keys as you can see in the text to see the other effects.

And a silly story: There was a time I finished coding several effects for my CloseGL demo and then I wanted to contact the Nasty Bugs members through email and send them an attachment with the preview. I've given a preview where you need to press Space to check each part (I didn't wanted to make a separate EXE for each diferrent effect) and I tried to tell them in the email "PLEASE! Use Space to see the next part! There are several parts there!!!". I think I got an email from our musician who spoke about the one and single effect and what kind of music would fit in it's movement. I replied and told him "hey you haven't checked the rest effects!". Then after a month or so, I asked another one of our coders in MSN what did he think and he said "Heh, nice effect, do you have more?". Crazy! And the two other members only at the demoparty where I was finishing the demo, understood that you had to press SPACE to check several parts!!! Man,. that's crazy =)

And now I learned from that incident and thought that a text saying there are more parts and you have to press something, would make everyone understand

[Optimus]

Shockwave: Thanks for the ideas. Yes, I hate that distortion on the cube (It's there in the plasma cube too, but the weird plasma shapes hide it well , I was thinking of the second solution, but the first one is something that I haven't thought before. Clever one!

But I want to know more about perspective correction. Didn't got something exactly in your explanation "Or use the perspective correction formula, instead of interpolating U,V, interpolate U/Z, V/Z and 1/Z and at each pixel divide the texture co-ordinates by Z."

Do you mean, first interpolate U/Z, V/Z and then multiply the results by Z to get the U,V? Why would you need to interpolate for 1/Z too?

[Shockwave]

The method of subdividing the cube faces is a cheating method but trust me it works really well and the warping will not be noticeable on the cube, but for satisfaction, it's better to have perspective correct texturing.

Here is in essence what I was saying, here's the slow way of doing it in pseudo code.


 UU = U/Z
 VV =  V/Z
 ZZ = 1/Z

 for x=start to end
         u2 = UU / ZZ
         v2 = VV / ZZ
         plot (x, y, (texel u2,v2)
         UU += deltaUU
         VV += deltaVV
         ZZ += deltaZZ
 end


Obviously the problem with the above is the two divides but we can get rid of one of the divides like this ;


for x=start to end
         reciprocal = 1/ZZ
         u2 = UU * reciprocal
         v2 = VV * reciprocal
         plot (x, y, (texel u2,v2)
         UU += deltaUU
         VV += deltaVV
         ZZ += deltaZZ
 end

There is another method of doing perspective correct (which I believe is faster, if you google "3 magic vectors" you will find more info on that method, but the one I described is easier to grasp.

[ninogenio]

as shockwave said the best way to get rid of affine distorsion is to use 1/z but i find it quicker to use a w buffer and do it like this.

UU = U/Z
VV =  V/Z
w = 1/Z

for x=start to end

        if w_buffer(x,y)<w then
              reciprocal = 1.0/w
              u2 = UU * reciprocal
              v2 = VV * reciprocal
              plot (x, y, (texel u2,v2)
              w_buffer(x,y)=reciprocal
         endif

         w += deltaUU
         VV += deltaVV
         ZZ += deltaZZ
end

then you only do the divide on pixels that are getting drawn and also with the w_buffer gets rid of the need for a sorter i usually do it this way and have a backface culler on for good speed and procision.

[Tetra]

Looks great Optimus, fast too

Good going

[Shockwave]

Any more previews on this Optimus?

[Optimus]

Ok, I decided to upload one more teaser photo! =)

I've recently started scripting the actual demo with the wish the demo to be released hopefully in about one week. This is a screen from the starting part (not final and the object needs a bit of shading) with 3d blob stars, sine distorted logo of the team and a red bull object (thus the name of the demo ). There will be a GP32 and a PC version released at the same time with source codes (because our new group likes opensource). Maybe I'll release a GP2X port too.

[Shockwave]

Hehehe! Led Blur gives you wings
I'm looking forward to this one Optimus. Not too long to wait either! Thanks for the screenie.