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Question about terrain shaders?

Discussion in 'Editor & General Support' started by bigkahuna, Sep 19, 2006.

  1. bigkahuna

    bigkahuna

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    I searched here and the wiki and found some very nice, multi-texture terrain shaders (2 layer, 3 layer and 4 layer). But what I didn't find is a multi-texture shader that also supports bump mapping. Does this exist? Thanks!
     
    bigkahuna, Sep 19, 2006
    #1

  2. Alpha-Loup

    Alpha-Loup

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    I just wanted to post this myself a few days ago :D
     
    Alpha-Loup, Sep 19, 2006
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  3. Aras

    Aras

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    Well... aside that you can always write one yourself :roll: Do you want multiple base textures and a single bumpmap on the terrain? Or do you also want to mix multiple bumpmaps?

    Also, keep in mind that a bumpmapped terrain may quickly get very expensive to render. Bump-mapping by definition is per-pixel lighting, and it's much slower than the vertex lit terrain shaders.
     
    Aras, Sep 19, 2006
    #3

  4. Alpha-Loup

    Alpha-Loup

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    Well, my skills as a script kid are well evolving :D

    What i am currently trying to do (thats the reason why i did not post it ;) ), is using a single bump or normal map on a 4 level layerd terrain. I now know how to blend textures using alphas (YEAH!) and my layered shader works already.
    And i will surely get those bumps in... somehow and if necessary with a sledge hammer...

    If i get this one finished, hopefully, i will post it.

    Got any general advice, basic approach or dontdo´s for a complete code-newbie?
     
    Alpha-Loup, Sep 19, 2006
    #4

  5. Jonathan Czeck

    Jonathan Czeck

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    Also just wanted to remind, if the lights don't move in the scene, the bump mapped terrain is pointless and could just be made with normal diffuse texturing.

    -Jon
     
    Jonathan Czeck, Sep 19, 2006
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  6. Alpha-Loup

    Alpha-Loup

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    Yes, sure.

    A better approach is to build some eye-catchers and place them somewhere important instead of doing a complete bump-mapped terrain.
    But there are places in a level where such a shader could be very useful. Caves for example, where the player´s got the only light source.

    And it is a good point to start, when learning how to programm shaders. The code structure isnt that hard to understand (so far...) and you get fast and satisfying results...
     
    Alpha-Loup, Sep 19, 2006
    #6

  7. NicholasFrancis

    NicholasFrancis

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    @Jon:
    Not necessarily true - you can use bump maps like detail maps. I've also used bumpmaps for general terrain shading - If you generate a bumpmap of your terrain at 1024x1024 it gets REALLY nice shading no matter if it's actually quite lowpoly.
     
    NicholasFrancis, Sep 19, 2006
    #7

  8. bigkahuna

    bigkahuna

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    Never tried to write a shader before so I thought I'd ask before getting started...

    I thought I'd start with a single bumpmap, but would prefer to use multiple bumpmaps so I can tile them over large areas.

    Yes, I realise this. I've got pretty complex (ie. expensive) lighting in my underwater scene: I'm using an animated cookie on a directional light to simulate caustic effects and the user's vehicle has two spot lights they can direct into dark "caves". I'm getting about 45 - 50 fps on my Macintel iMac at max resolution, which I'm guessing means a lesser machine would get half that framerate or less.
     
    bigkahuna, Sep 19, 2006
    #8

  9. Aras

    Aras

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    Attached Files:

    Aras, Sep 20, 2006
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  10. Alpha-Loup

    Alpha-Loup

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    :D

    Well, thanks Aras! I cant wait to analyze it!

    I love this forum.
     
    Alpha-Loup, Sep 20, 2006
    #10

  11. Jonathan Czeck

    Jonathan Czeck

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    Still trying to understand this. :) The bump map buys you better shading than just vertex shading. I get that. But if the lights are static shouldn't that all be baked into a lightmap?

    Also, is a detail map cheaper than a bump map? Why would you prefer to use a bump map? Thoughts are appreciated.

    Thanks
    -Jon
     
    Jonathan Czeck, Sep 20, 2006
    #11

  12. bigkahuna

    bigkahuna

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    WOW :!: Thanks :!:
     
    bigkahuna, Sep 20, 2006
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  13. Aras

    Aras

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    For a start, yes, if the lighting is static, there's (almost) no reason to use bumpmaps. There may be some reason to use them, if your terrain is really very-non-flat and bumpmap contains steep areas. In that case a "real bumpmap" will get proper lighting, whereas a baked texture, tiled over the terrain only approximates that (because the same texture is tiled over flat and steep terrain areas).

    Yes, a detail map is cheaper. A lightmap is cheaper. Mostly because both don't require using pixel lights, so you can just use vertex lighting.

    So about the only reason is "correctness" (see above) or per-pixel effects such as light cookies and good looking small point lights near the terrain. In that case you need a pixel lighting shader; and a diffuse+bump is not much more expensive than just per pixel diffuse (a couple of instructions and one more texture to read).
     
    Aras, Sep 20, 2006
    #13