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Index › Programming Questions & Help › OpenGL and 3D Libraries › gradient background in 3D space
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gradient background in 3D space (Read 1005 times)
julapy
gradient background in 3D space
Apr 14th, 2008, 5:05am  
hi, currently i have some particles flying around in 3D space with the camera following one of the particles.

im trying add a gradient background like a light source in space.  this i hope will give the camera some orientation.

ive tried enclosing the scene in a sphere and shinning a spotlight onto the inside of its faces. this worked to some degree but had some limitations like, i couldn't get the gradient to work over the entire sphere, only for one of its hemispheres. also, i had no control over how much the light dissolved over distance.

im not convinced with my approach and id love to hear of other techniques people have used.
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sgsrules
Re: gradient background in 3D space
Reply #1 - Apr 14th, 2008, 5:23pm  
use multiple spotlights and play with the light cutoff angle, and  falloff. Another alternative would be to use a texture on the sphere.
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Stephen Shepard (sgsrules)
 
Cycleswithin
Re: gradient background in 3D space
Reply #2 - Apr 14th, 2008, 5:50pm  
I've been thinking about doing this too.

I thought that I could just create a big flat vertex shape with a gradient texture applied to it and then pushed right to the back (with all the z-sorting stuff). This is sort of like mixing 2D with 3D though and apparently hint(DISABLE_DEPTH_TEST) - can't remember exactly - should enable you to do this (but i can't get it working, but haven't spent much time on it).
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flight404
Re: gradient background in 3D space
Reply #3 - Apr 14th, 2008, 10:51pm  
I use textured spheres myself.  Working on a piece now that needs to have a subtle but animated background so I am using a few nested spheres with slightly different textures and rotation speeds.  Works fairly well.  Its not ideal but it gets the job done.
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Robert Hodgin {flight404}&&
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julapy
Re: gradient background in 3D space
Reply #4 - Apr 15th, 2008, 12:26pm  
just tried the textured sphere approach and it looks great!
thx very much for all ur help.
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julapy
Re: gradient background in 3D space
Reply #5 - Apr 17th, 2008, 5:34am  
got excited too soon.

im using the TexturedSphere example that comes with processing. problem is, I can't find a way to deform my image in the same way as in "world32k.jpg". i've tried spherical mapping filters in photoshop but it still leaves the image bulging on the sphere.

i think the reason for this is, the sphere in the TexturedSphere example is rendered using two parts, the spherical caps and the cylidrical middle section.

need to work out a way to distort my image to match this render.

or does anyone have any other approach.

cheers in advance.
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