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Thread: Shadows Not Right-Help

  1. #1
    Cobra Commander! mamurphy's Avatar
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    Unhappy Shadows Not Right-Help

    I'm having an issue with shadows cast by an object with an alpha map in the transparency channel of the suface editor.

    To make it simple I created two flat polygons: One for the floor to receive the shadow and the object to cast it.

    With shadow map on it cast a solid shadow (No alpha transparency) onto the floor.

    With ray trace shadows it didn't cast anything-(yes I had ray trace shadows on.)

    I don't know if this can be done, but I believe it can.

    I'm posting a couple of pics to show what I mean..the one of the left is the shadow map and the one on the right is the ray trace.

    I'll also post my settings....

    I'm sure someone out there can help me figure this out..I checked the manual, the message boards and Inside LW 7 and can't find the answer.

    Thanks
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  2. #2
    Cobra Commander! mamurphy's Avatar
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    Here are my settings
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  3. #3
    Beyond Reality WizCraker's Avatar
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    Use a clip map instead of a transparency map to get it give you the correct shadows.
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  4. #4
    Cobra Commander! mamurphy's Avatar
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    GREAT!

    It works with shadow map but not ray trace shadow (Using a spot light)

    Is that right, or do I need to be aware of another setting for raytrace shadows?

    Thanks again!!!!!
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  5. #5
    Super Member SplineGod's Avatar
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    When using clip maps make sure to turn off texture anti aliasing or you may get funky results. So if you need smoother edges to clip maps make them higher rez.

  6. #6
    Cobra Commander! mamurphy's Avatar
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    Thanks Larry,

    BTW, is there a particular ratio of pixels to LW units to use or keep in mind when building clip maps/texture maps?

    for example, if a cube is 1 meter square and will be output to NTSC resolution, what would be the best size/resolution for clean clips and close ups of textures?


    (Larry, I'm trying to make up my mind to buy your training courses. I've worked through your fabulous freebies and learned a tremendous amount. Look forward to a purchase of your Intro to LW soon!)

    ps-My avatar is the result of expanding on your freebie subpatch head modeling tutorial!!
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  7. #7
    Super Member SplineGod's Avatar
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    Originally posted by mamurphy
    Thanks Larry,

    BTW, is there a particular ratio of pixels to LW units to use or keep in mind when building clip maps/texture maps?

    for example, if a cube is 1 meter square and will be output to NTSC resolution, what would be the best size/resolution for clean clips and close ups of textures?


    (Larry, I'm trying to make up my mind to buy your training courses. I've worked through your fabulous freebies and learned a tremendous amount. Look forward to a purchase of your Intro to LW soon!)

    ps-My avatar is the result of expanding on your freebie subpatch head modeling tutorial!!
    Hey Thank you!
    Theres no particular aspect unless you need them for background images or plates then you need to worry about that. For a texture map it doesnt matter because you can resize them. What does matter is the resolution if you plan to get pretty close.

    Thats cool the you were able to expand upon the freebies to do your avatar.

    As far as my training courses go, the freebies I have are scratching the surface when it comes to the rest of the courses and the online support I provide. The face modeling is just the first 20 minutes or so of the Character modeling Module which is about 15 hrs by itself. The full course is over 60 hours. If you really are interested drop me an email and lets see what we can do. You can also check out my support forum HERE . Login as guest, password guest.
    If you take a look youll see that I do provide good support and students really are learning valuable information.

  8. #8
    One point that needs to be made clear is that Shadow Maps do not see transparency (as in the surface channel - they do of course work with clip map type 'transparency'), you will get the same opaque shadow regardless of trans. level.

    If your raytrace shadows are not showing up then you need to either flip the polys or make them double sided - one-sided polys only cast shadows in one direction.
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  9. #9
    Super Member tburbage's Avatar
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    If you have a non-solid object like a plane of one or more polys which you want to use a transparency or clip map on (to represent a grid or something)

    -- and you want a ray traced light to do the shadow casting

    -- either double to polygons of the plane and flip the copy or, easier, set the surface attribute of the plane's surface to "double sided"

    There have to be normals facing the object receiving the shadows for ray traced shadows to show up.

    As already pointed out, a shadow mapped spotlight will also work in this situation. That doesn't help for your other types of lights, though...

    The only way I know of outside of manipulating the shadow in post to get a diffuse shadow would be spinning lights.

  10. #10
    Newbie Member
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    Please forgive my ignorance level but would any of you tell me what's the difference (technically) between alpha and clip map?

    Ezequiel

  11. #11
    Alpha channel is used to mask out parts of a 2D image or footage. Clip map is a black&white image that's used to mask out parts of geometry from being rendered in a 3D program.
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  12. #12
    Newbie Member
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    Tanks a lot Toby
    Now I get the idea. Rather important difference I would say

    Tanks again
    Ezequiel

  13. #13
    nice to have someone from BA!

    didn't it get wiped out by the Arachnids?
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  14. #14
    Newbie Member
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    I'm sorry I'm afraid I didn't understand the thingy about the arachnids, I would like to know a lot more of english. It's a cool language, anyway thanx for the comment.
    I'm glad that I can share common interests and knowledge with people like you in this forum. It's very cool.

    Does Wipe mean the same as bite?

    Ezequiel

  15. #15
    sorry, I was refering to the Starship Troopers movie, bad joke, I know -

    'wiped out' is like 'destroyed quickly and completely'
    Confirmed -
    No Weapons of Mass Destruction
    or links to Al Queda or 9/11. (Sep. 2003)

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