Voxel Rendering (Beginner)

This is a discussion on Voxel Rendering (Beginner) within the C++ Programming forums, part of the General Programming Boards category; Hi, Im trying to build a voxel renderer, however im going to need some help as I am a total ...

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    Voxel Rendering (Beginner)

    Hi,

    Im trying to build a voxel renderer, however im going to need some help as I am a total beginner to this.

    Im going to use the ray casting technique, and im going to cast through every pixel on my view plane. My question is given my 3D Array of pixel values (R,G,B) how do I cast the ray and find which voxel (element in 3d array) the ray hits?

    Many Thanks
    -Alex

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    Something like this? (And following pages.) http://www.permadi.com/tutorial/raycast/rayc4.html
    dwk

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    Yes, something like that.

    However, that takes shortcuts and uses strips and other optimizations that I don't want. I ideally want it to cast through every pixel on the view plane and calculate the colour of that pixel based on the intercept of the ray and an actual voxel.

    Sorry If Im not making any sense, im really new to this

    Cheers
    -Alex

  4. #4
    Frequently Quite Prolix dwks's Avatar
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    So . . . you want a ray that passes through every pixel in your 3D space? What do you mean?

    BTW, I probably shouldn't be helping you with this, I'm newer than you are.
    dwk

    Seek and ye shall find. quaere et invenies.

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    Quote Originally Posted by dwks View Post
    So . . . you want a ray that passes through every pixel in your 3D space? What do you mean?

    BTW, I probably shouldn't be helping you with this, I'm newer than you are.
    No.

    There is a view Plane (The eventual image you see). You shoot a ray from a constant point through each pixel on the view plane. Follow the ray through until it hits the closest voxel in its path.

    I just don't know how to find the intercept of the ray and voxel mathematically/programming.

    Cheers
    -Alex

  6. #6
    Frequently Quite Prolix dwks's Avatar
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    I really have no idea. The only thing I can suggest is to keep looking. Perhaps the tutorial I posted has the answer to your question later on, such as here: http://www.permadi.com/tutorial/raycast/rayc7.html
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
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    Quote Originally Posted by dwks View Post
    I really have no idea. The only thing I can suggest is to keep looking. Perhaps the tutorial I posted has the answer to your question later on, such as here: http://www.permadi.com/tutorial/raycast/rayc7.html
    Yeah,

    Had a look through it. Not really what I wanted, it seems to cut many corners to get a good frame rate.

    All I want really is an algorithm (simple not optimised) to calculate the closest voxel intersection along a ray.

    Cheers
    -Alex

  8. #8
    Frequently Quite Prolix dwks's Avatar
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    How about this hit from here?

    The basic algorithm looks pretty simple.
    Code:
    loop {
        if(tMaxX < tMaxY) {
            tMaxX= tMaxX + tDeltaX;
            X= X + stepX;
        }
        else {
            tMaxY= tMaxY + tDeltaY;
            Y= Y + stepY;
        }
        NextVoxel(X,Y);
    }
    It probably glosses over a lot of details, though.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
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  9. #9
    Registered User Frobozz's Avatar
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    Ken Silverman released the source code to his voxel library if you want to check it out. His coding tends to be messy though.

    http://www.advsys.net/ken/voxlap/voxlap05.htm

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    Super Moderator VirtualAce's Avatar
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    If you are casting a ray from the viewer through every pixel on the screen you are not doing voxel rendering, you are doing ray tracing.

    Voxel rendering is an approximation using volumes and does not require that you ray-cast the entire screen. There are several methods of rendering voxels but the ray-casting method is more suited to terrain than it is 3D objects.

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    Quote Originally Posted by Bubba View Post
    If you are casting a ray from the viewer through every pixel on the screen you are not doing voxel rendering, you are doing ray tracing.

    Voxel rendering is an approximation using volumes and does not require that you ray-cast the entire screen. There are several methods of rendering voxels but the ray-casting method is more suited to terrain than it is 3D objects.

    Ok i only got the ray casting idea from a voxel terrain tutorial. Could you please explain further the proper technique?

    Thanks
    -Alex

  12. #12
    Super Moderator VirtualAce's Avatar
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    In one post? Hehe. No way.

    Google it.

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