What's wrong with this OpenGL model picking code?

  • What's wrong with this OpenGL model picking code? openglNewbie

    I am making simple model viewer using OpenGL. When I want to pick an object OpenGL returns nothing or an object that is in another place.

    This is my code:

    GLuint buff[1024] = {0};
    GLint hits,view[4];
    glGetIntegerv(GL_VIEWPORT, view);
    //I make the same transformations for normal render
    glTranslatef(0, 0, -zoom);
    for(int j=0;j<allNodes.size();j++)
    hits = glRenderMode(GL_RENDER);

  • Do you have an ATI card? I think they deprecated some portions of OpenGL (picking included) a long time ago.

  • No one use OpenGL picking this days, you have to implement it yourself. Transforming from camera to worlds space is a bit tricky, here is a good article http://trac.bookofhook.com/bookofhook/trac.cgi/wiki/MousePicking

  • Ok, but for 3d viewer application opengl isn't better ? My doesn't work, beacouse I have two mistakes: 1.




    So it is looking that picking still works on ati, my friend said my that picking can be making by software implementation of opengl.

  • OpenGL picking using the selection buffer is deprecated. If your scene is small enough, you should use colour-based picking; otherwise, you can use gluUnProject to obtain a world coordinate from a mouse coordinate and a depth read from the depth buffer using glReadPixels().

c++ opengl graphics-programming
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