在OpenGL中如何实现拾取？我的部分代码如下,各位帮忙看看，感激不尽了

Question

在DrawTargets 中画点：
BOOL CRenderView::DrawTargets()
{
    double x,y;
    for (int loop = 0; loop < 3; loop++)
{
glLoadName(loop);
x = loop / 4.0;
y = loop / 4.0;
Drawpoint((float)x, (float)y);
}
return TRUE;
}在Selection中拾取：
如果被选中的物体个数hits大于0，则画另一个点，这只是权益之计，为了测试
Selection()能否成功。BOOL CRenderView::Selection()
{
    GLuint  buffer[512];
    GLint    hits,viewport[4];
    
    glGetIntegerv(GL_VIEWPORT, viewport);

    glSelectBuffer(512, buffer);
   (void) glRenderMode(GL_SELECT);

    glInitNames();
    //Initializes The Name Stack
    glPushName(0);

    glMatrixMode(GL_PROJECTION);
    // Selects The Projection Matrix
    glPushMatrix();
    glLoadIdentity();

     gluPickMatrix((GLdouble) mouse_x, (GLdouble)（viewport[3]-                    mouse_y),   0.1f, 0.1f, viewport);
     gluPerspective(45.0f, (GLfloat) (viewport[2]-viewport[0])/ (GLfloat)( viewport[3]-viewport[1]), 0.1f, 1.0f);
     glMatrixMode(GL_PROJECTION);
     glPopMatrix();
     glMatrixMode(GL_MODELVIEW);
     hits = glRenderMode(GL_RENDER);
     if (hits > 0)
     {
Drawpoint((float)-0.3,(float)-0.3);
return TRUE;
     }
     else
return FALSE;
}

Answer 1

你得在Selection()函数中画图形啊
GLfloat curprojection_matrix[16];
glGetFloatv(GL_PROJECTION_MATRIX, curprojection_matrix);
glGetIntegerv(GL_VIEWPORT, viewport); glSelectBuffer(BUFFERSIZE, selectbuff);
glRenderMode(GL_SELECT); glInitNames();
glPushName(0); glMatrixMode(GL_PROJECTION);
glPushMatrix(); glLoadIdentity();
gluPickMatrix((GLdouble)point.x, (GLdouble)(viewport[3] - point.y),  5, 5, viewport);
glMultMatrixf(curprojection_matrix);
//画目标
         DrawTargets();         glFinish();
glPopMatrix();
hits = glRenderMode(GL_RENDER);