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View Full Version : Texturing a Sphere or Teapot.



MrShoe
12-03-2000, 07:54 PM
I know how to texture quads and triangle, but how do you texture spheres and teapots (drawn by glut)? Where do you put the texture co-ordinates and how since there are no verteces??

Nutty
12-04-2000, 01:07 AM
you have 2 options. Either turn on auto texture coord generation (for like sphere mapping) or create your own objects in max or somat, and load them up with their texture coords. And render them yourself.

Nutty.

MrShoe
12-04-2000, 07:29 PM
Ammm, please explain how to turn on auto-texture coord generation, for I have no idea!
http://www.opengl.org/discussion_boards/ubb/frown.gif

Nutty
12-05-2000, 12:11 AM
First you need to turn on auto texture coord generation.

glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);

these can be anywhere. Also use the glDisable with these arguments to turn it off.

Then after binding your texture (probably at texture setup) do this.

glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, mode);
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, mode);

where mode is one of these.

GL_SPHERE_MAP
GL_EYE_LINEAR
GL_OBJECT_LINEAR

Use the same one for each GL_S and GL_T.

(As a side note in cube mapping you need to use GL_R too, though using on a GL_TEXTURE_2D, creates an error under my Geforce.)

I'm pretty sure glTexGeni is per texture object. i.e. not an overall state.

For a funky environment mapping effect use SPHERE_MAP

hope that helps!
Nutty http://www.opengl.org/discussion_boards/ubb/cool.gif

dhbyrne
12-05-2000, 04:22 AM
Nutty can you help me also, i have a similar problem and i dont kow what to do. I have read that you have done a planet system from another reply of yours. Im working on the one from the "Red Book", added lighting etc but i need to be able to give a colour or texture to the planets, can you suggerst anything or send me somewhere to do it

Nutty
12-05-2000, 05:24 AM
How are you rendering the planets? Are you useing gluSphere or somat? If so, then to set the color probably do glColor3f(r, g, b);
before calling it.

As for textures, you'll need someway of specifying the texture coords on the sphere. Usually I scour the net for free models of planets with them already textured and use them! http://www.opengl.org/discussion_boards/ubb/smile.gif

If ya need more help give me a yell.

Nutty