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# J

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1. ## Applying texture on a sphere [raytracing]

I have to specify a couple of vector to define the sphere ? On the 0.x axe and 0.y axe ? And is it on a cartesian reference ?
2. ## Applying texture on a sphere [raytracing]

Hi guys ! I'm doing a raytracer in C. I have to apply textures on a sphere. I have the coordinates x, y,z where my ray hits the sphere, the radius of the sphere and a function that returns the color of the pixel of the texture for a given x and y. Do you have a formula to get the x,y of the texture from the x,y,z of the sphere and the radius r ? Ty !
3. ## Raytracing: how to use Perlin noise functions.

Ok i just multiplied my input coordinates by 0.1 and i got some nice results ! Thank you I'll post when i'll see new problems.
4. ## Raytracing: how to use Perlin noise functions.

So i need to transform my coordinates to a value between 0 and 1 ?
5. ## Raytracing: how to use Perlin noise functions.

I used the noise3() function with all the 3d points of my objects, then i got a return value (double). I choosed 2 default colors (and the third one was the one of the object). I choosed 3 default values, 0.25, 0.5 and 0.75. And i did this: t_color get_texture(t_color c1, t_color c3, t_color c2, double tab[3]) { t_color text; double v; double f; int i; i = 0; while (i < 8) { v = v + noise3(tab); i++; } if (v <= s1) text.color_int = c1.color_int; else if (v < s2) { f = (v - s1) / (s2 - s1); text.color_char[0] = 0; text.color_char[1] = (c1.color_char[1] * (1 - f)) + (c2.color_char[1] * f); text.color_char[2] = (c1.color_char[2] * (1 - f)) + (c2.color_char[2] * f); text.color_char[3] = (c1.color_char[3] * (1 - f)) + (c2.color_char[3] * f); } else if (v < s3) { f = (v - s2) / (s3 - s2); text.color_char[0] = 0; text.color_char[1] = (c2.color_char[1] * (1 - f)) + (c3.color_char[1] * f); text.color_char[2] = (c2.color_char[2] * (1 - f)) + (c3.color_char[2] * f); text.color_char[3] = (c2.color_char[3] * (1 - f)) + (c3.color_char[3] * f); } else text.color_int = c3.color_int; return (text); } whit t_color as: typedef union u_color { int color_int; char color_char[4]; }t_color; The result was a random snow. So i think i didn't use the noise3() function.
6. ## Raytracing: how to use Perlin noise functions.

Hello guys, I'm doing a raytracer in C and I need to apply some textures on 3D objects. I saw the noise functions created by Ken Perlin, http://mrl.nyu.edu/~.../doc/oscar.html and i think I could use the noise3() function to apply texture on my 3D objets. I tried to use this functions in my program, but it didn't work. I'm wondering how to use this noise3() function and the return value to get a good texture. Thanks guys for helping me
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