[osg-users] Mapping texture coordinates to a portion of a large (.obj) model

Isaac Wolf ijwolf8 at gmail.com
Thu Oct 25 13:11:58 PDT 2018

Hello all,

I am new to OSG, and I am having some difficulty understanding the steps required to complete this task.

Basically, I want to map an image to a portion of a .obj file I am loading in as a Node. I have the 3D position and indices of four points that I would like to use as UV coordinates for an incoming image.

My primary issue is that the .obj doesn't have texture coordinates in the first place. So I figured I could add the only 4 points I care about manually, and assign them as UV coordinates.

Is this possible? Or do you always need a 1 to 1 mapping for texture coordinates? In pseudo/osg inspired code, I'd image it would look something like the following. 

Say I had a Vec3 array of 4 points that sit on the surface of a model called points_of_concern, and a uv_array that is just  <0,0>, <0,1>, etc.


<Node> myNode= readNodeFile("model.obj");
Vec3 points_of_concern=[<2.3, 3.2, 3.1>, ....];
Vec2 uv_array= [<0,0>, <0,1>...];

Texture2D myTex = readImageFile("image.png");


It seems like a simple task, but I did a lot of searching without any luck!

Thanks for your time!


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