Real Time motion Blur ?

BlitzPlus Forums/BlitzPlus Programming/Real Time motion Blur ?

Paul "Taiphoz"(Posted 2003) [#1]
Hay all im coding a game that requires a Twister.

http://www.teamrebellion.co.uk/GFX_Demos/twister.zip

My code is above, I plan to add the above code to my game, What im wondering is if there is a way I can motion blur the above twister, and still having it look good as it passess accross my game level.

I havent dont motion blur before so I havent got a clue where to start..

thanks for any help.


_PJ_(Posted 2003) [#2]
I would have thought perhaps creating an exact copied replica of the twister, making it semi-transparent, and always very slightly behind the original. (?)


Paul "Taiphoz"(Posted 2003) [#3]
How big a drag on the CPU would that be though ?

My game already has a lot going on. I need a way of doing this that will keep the CPU drain as low as possible.


John Pickford(Posted 2003) [#4]
You'll need to use 3D if you want lots of transparency effects. You can still write 2D games in 3D but you get the benefit of alpha, scaling, rotation etc.


(tu) ENAY(Posted 2003) [#5]
Try this:-

http://enaysoft.co.uk/parp.zip

What I've done is invertly dither masked your images into 2 seperate frames. Basically if you drew them together, you'd get the full frames again.
But I've made it flicker quickly between them, giving you an odd flickery/blurryish effect. I've flickered half in one frame and half the other so you get a better blurry effect.
Not a real motion blur, but probably the best you'll get using Blitz2D.

The good thing is though, not only are your particles transparent now, so you'll be able to see everything behind the particles, but also there is no extra CPU added, just a slight fraction of memory extra for the extra frame, it'll be no slower than your original algo.

If you want the source code I used to dither mask your image I'll let you have it.

Hope this helps. :)


Oldefoxx(Posted 2003) [#6]
I think in part it depends upon how realiztic you want it to appear. Real tornatoes are identified by their content - dirt, trucks, siding, roofs, cows, whatever, but mostly debree. And their contents are constantly being hurled out of the funnel, so you have this arching effect with objects being first picked up then cast aside later. So they are black, or brown, or even white (if they are water spouts).

If you want just a stylized tornato, one that you can draw as a series of spiraling lines that form the general shape of a funnel, then you could draw several such graphics and alternate between them rapidly, You could even reverse them, left to right, for some additional variance. There should be no problem with being able to see "through" them (although in a real tornatoe, the view is generally blocked if there is a lot of debree).

Stylized tonatoes are often preferred because they are "fun" things, detached from the real world ones that can do serious damage. Actually though, you can increase the illusion of speed (blur) by replacing lines with a paint brush and feathering out the effect as you paint the twisting effect for the funnel. But to do this, you would probably have to look at a paint or illustration package where you can paint the general shape by hand and save it to an image file, which you would then load and use in Blitz.

At least that is the way I would plan to go at it.