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airseb
06-17-2003, 09:06 AM
Hi !
i have read this :http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=36

i'm not sure of having understood this tutorial :
it displays an object, render it to a texture and then reduce the size of the texture by keeping the luminance of the object and it redisplay the object ?
that's all ? have i forgotten something ?
but what is the light which come from the object, except the one of glLightfv (that we can see by downloading the code) ?
lightings are they obligatory ?
thanks.

rgpc
06-17-2003, 09:14 PM
This isn't really suitable to this forum (doesn't Nehe have his "own" forum?)

However, if I understand you correctly you are asking what is the "mist" emanating from the spring in the demo? (Which could be interpreted as light radiating from the object through mist)

That is the very topic of the whole tutorial - and is created by the DrawBlur() function. It is the radial blur effect...

airseb
06-17-2003, 11:56 PM
Originally posted by rgpc:
This isn't really suitable to this forum (doesn't Nehe have his "own" forum?)

However, if I understand you correctly you are asking what is the "mist" emanating from the spring in the demo? (Which could be interpreted as light radiating from the object through mist)

That is the very topic of the whole tutorial - and is created by the DrawBlur() function. It is the radial blur effect...


yes but how by reducing the texture, it produces light ?

nystep
06-18-2003, 01:18 AM
it is called alpha blending.

rgpc
06-18-2003, 07:21 PM
Originally posted by airseb:

yes but how by reducing the texture, it produces light ?

It doesn't produce light, it blurs the image! The "light" is created by drawing a series of quads over the scene with increasing size and decreasing alpha. That's what the "DrawBlur()" function does (look at the code, read the tutorial and then play with the source - you'll learn something).