Normal mapping - Environment mapping

Posted By: Julius

Normal mapping - Environment mapping - 07/21/05 05:46

i've never even tried shaders, and i won't be able to until i get a better version of A6 (i have Extra), so i could be completely wrong, but couldn't normal maps be used to make smoother environment mapping effects? i've seen environment mapping (using cube maps of course i don't kno if ther is another way) used all the time but it looks really jagged on models that aren't really high-poly. couldn't a smoother reflection effect be made using environment mapping with normal mapping? it probably has already been done if its anywhere near as easy as it sounds to me but i jus havn't seen it.

julius
Posted By: Nadester

Re: Normal mapping - Environment mapping - 07/22/05 08:35

Enviromental bump mapping, like most water effects, is normal mapping with an enviromental map (in essence).
Posted By: Julius

Re: Normal mapping - Environment mapping - 07/22/05 09:12

i see what u mean ther, but i just don't see why i havn't seen for example people using normal mapping with environment mapping to make really smooth reflections on cars (which almost always have environment mapping, and usually (unless the car is really high-poly) have jagged reflections).
Posted By: Matt_Aufderheide

Re: Normal mapping - Environment mapping - 07/22/05 15:47

What you are saying makes no sense ... how could using a normal map to do environment mapping make it better? unless you are environmental bump mapping there is no reason to use a normal map.
Posted By: Julius

Re: Normal mapping - Environment mapping - 07/23/05 09:24

reflections done with environment mapping usually look jagged. i don't know much about environment mapping, but from what i kno (which could be completely wrong) cubic environment mapping takes a cube-map image and according to the camera's position in relation to the model and the normals of each of the model's vertices, finds each vertex's position on the cubemap (in such a way that would simulate a reflection), and interpolates each pixel's position between vertices on the cubemap according to each pixels position in relation to the vertices making up its face. i'm terrible at explaining stuff but i'm sure you know what i mean if you think about it (and maybe after you stretch what i said slightly to sound more like how you know it actually works). the thing is these "reflections" always look stretched and jagged.
using a normal map and the normals of each face couldn't you figure out new normals for each pixel (in the same way however it works when normal mapping is used to alter a models lighting), and just colour that pixel according to a place on the cubemap (which is determined by the pixel's new normal and the camera's position in relation to the model)? i hope you know what i mean. or maybe i'm completely lost. lol soz if i'm just wasting all ur time.

julius
Posted By: xoNoid

Re: Normal mapping - Environment mapping - 07/23/05 10:23

Using FFP environment mapping can be a bit jaggied. Try using environment mapping with a shader.
Posted By: Specterdragon

Re: Normal mapping - Environment mapping - 07/24/05 01:32

Quote:

using a normal map and the normals of each face couldn't you figure out new normals for each pixel (in the same way however it works when normal mapping is used to alter a models lighting)




What you're saying seems to make sense to me (just for the record). Unfortunatly I really don't have enough experience with environment mapping to be able to tell you if this is a better solution.

So basicly, I'm just chiming in to show that not everyone is opposed to the concept. I'll have to look into this.
Posted By: Julius

Re: Normal mapping - Environment mapping - 07/24/05 10:43

specterdragon i'm glad you're on my side lol!

Quote:

Using FFP environment mapping can be a bit jaggied. Try using environment mapping with a shader.




i would give anything a go if my i had an edition that supported shaders (i have Extra)! thanks anyway

julius
Posted By: Rhuarc

Re: Normal mapping - Environment mapping - 07/24/05 22:05

Environmental bumpmapping is a very basic shader... 3 lines of ASM

Code:
tex t0
texbem t1,t0
mov r0,t1


Or if you want to multiply it with a texture (t2)..
Code:
tex t0
tex t2
texbem t1,t0
mul r0,t1,t2



Tecnically environmental bumpmapping could be used to smooth out edges, yes, but the performance cost isn't worth it in my opinion... In the exact same way normalmapping can add shading detail to a model (as if it had more polys), it can also add reflection detail- in both cases it is only changing the normals per-pixel.

Case and point: sure you can do it... is it worth it? probably not. Simply caclulating the reflection in a vertex shader rather than the FFP will correct a lot of streaking/stretching that appears at odd locations.

-Rhuarc
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