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Type: Posts; User: dmy

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  1. Replies
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    Re: URGENT!!!! OpenGL texture problem

    i seen the screenshot, but didn't identified anything strange about it... what is the problem exactly ? what should be shown, but instead is not ?
  2. Thread: moving Pattern

    by dmy
    Replies
    1
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    254

    Re: moving Pattern

    if the pattern repeats, then i would use a texture, then render a quad with this texture.
    then, before scrolling the texture (using the texture matrix makes it easy) i draw only those pixels wich...
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    Re: Using Textures for Non-Visual Data?

    what are you trying to do in the first place ?

    < :) >
    my wild guess is that it seems like you're trying to extend the "color-ID-picking" approach (rendering primitives with a certain color,...
  4. Thread: Strauss Lighting

    by dmy
    Replies
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    3,138

    Re: Strauss Lighting

    ok, i got your point: statistically, light-matter interactions can be modeled exactly as diffuse+specular... good to know, thanks k.
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    Re: General-purpase bending code

    good to hear :)
    btw, what are you going to use it for, maybe some modeling app... ?
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    Re: General-purpase bending code

    here's my algorithm, it works as the one in 3DSmax:

    V3 rot( V3 in, float angle ) {
    float s = sin( angle );
    float c = cos( angle );
    return V3(
    c*in.x - s*in.y,
    s*in.x + c*in.y,
    in.z...
  7. Replies
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    4,960

    Re: General-purpase bending code

    the equation i suggested cannot in fact bend a cylinder to a torus: i've discovered it just yesterday.
    to do it, a different equation and method is needed.

    since it is an interesting topic, i'm...
  8. Thread: Strauss Lighting

    by dmy
    Replies
    18
    Views
    3,138

    Re: Strauss Lighting

    @korval:
    you are misunderstanding me, i've never supposed you made up the things you said 'cause i know my physics too,
    simply you didn't understood what i was talking about. if i offended you, i...
  9. Replies
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    Re: Only one light working

    light positions get transformed by the mv matrix as any other vertex you submit:
    have you tried to specify them once per frame and not only at init time ?

    something like:

    // every frame
    ...
  10. Replies
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    Re: General-purpase bending code

    if you're in need of a bender like the tool in 3DSmax, then you do not want the sort of tapering you talk about...
    because if you have your cylinder for example, when you bend it, it won't resemble...
  11. Replies
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    4,960

    Re: General-purpase bending code

    try this:


    p1 = rot( p0, a * len( 0, p0 ))

    where:
    p0 input vertex
    p1 output vertex
    rot rotation around some axis
    a amount of bending (0=none)
  12. Replies
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    Re: Create texture w/o copying pixel data to it?

    also, you could get pixels from the the framebuffer with glCopyTexImage2D: no need for a starting sysram buffer then.
  13. Thread: Strauss Lighting

    by dmy
    Replies
    18
    Views
    3,138

    Re: Strauss Lighting

    specularity and diffuseness are abstraction/models, created by us, in the strive to get something simple to work with.

    light do not work as in our model, but it's the model wich only loosely...
  14. Thread: Rotation Inversion

    by dmy
    Replies
    4
    Views
    851

    Re: Rotation Inversion

    rotation inversion via transposition always worked for me ... all i can say, remember opengl uses a right-handed reference frame, so watch out for wrong signs in you math.
    also, for little...
  15. Replies
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    Re: Texturing with TGA images

    it don't work because you missed some concepts about textures.
    in opengl (i think i became core with version >= 1.1) there is the concept of "texture object" and "current texture": you can have as...
  16. Replies
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    Re: cubic spline to NURBS

    if a tube is what you need, then look for frenet frame.
    i can give some catmull-rom/B spline code i have if you need it to start.
  17. Replies
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    Re: cubic spline to NURBS

    i don't think nurbs can be made to interpolate knots without loosing C2 continuity (keep the curve smooth), but i can be wrong.

    for sure it involves tweaking the knot weight and maybe even the...
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    Re: transparancy question

    or else, if your image is simple black and white, you can load it as a alpha texture.
    then you render it with alpha testing enabled.
  19. Re: Win32 application freezes with certain dialog boxes

    it's because of the message pump: it must never stop.
    my suggestion is to open the blocking dialogs in separate threads.
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    Re: drawing with white as transparent

    a similar question just somedays ago: post

    opengl does not color-keying natively. maybe there's an extension but i didn't found it.

    to draw sprites, the easier way is to add the alpha...
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    Re: glDrawPixels and transparency

    as i said, you need to have alpha bits in your image to use alpha testing.
  22. Re: Funny phenomenon(maybe related to perpective?)

    the code seems conceptually right...
    if it only fails with a single tire, then i would look elsewhere for the bug: check the function wich evaluates the tires positions.

    if it is all right...
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    Re: Textures and Lightning

    this happens because for the floor you need to enable texturing, but for the table you don't want it.

    before drawing the table you should do:
    glDisable( GL_TEXTURE_2D );

    and before drawing the...
  24. Thread: Color manipulation

    by dmy
    Replies
    3
    Views
    360

    Re: Color manipulation

    1 -
    change the material/light properties while rendering

    2 -
    glReadPixels/glDrawPixels with blending as a rendering post process

    3 -
    vertex/pixel shaders during rendering

    method 1 and 3...
  25. Replies
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    Re: Lighting is confusing...

    how did you set your materials ?
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