Selection objects via mouse is driven me crazy

Hi guys.
I try to get the code to work, but i don´t see why it doesn´t work. The function will be called by “OnMouseClick” in MFC and receive X and Y Pos of the Mouse which are ok.

Please don´t send me any tutorial links. I got enough and thought that i understand them

void COpenGL::select_object(int xPos, int yPos)

GLuint buffer[BUFFER_LENGTH];
GLint hits, viewport[4];
glGetIntegerv(GL_VIEWPORT, viewport);		// Get the viewport
glSelectBuffer(BUFFER_LENGTH,buffer);		// buffer muss für jedes Object das ausgewählt wird 4 byte bereitstellen
(void) glRenderMode(GL_SELECT);				// Change render mode


glMatrixMode(GL_PROJECTION);			// Switch to projection and save the matrix

gluPickMatrix( (GLdouble) xPos,(GLdouble) (viewport[3] - yPos),5,5,viewport);
    // TEST ***************************
glLoadName (0);
    glPushName (1);
    glColor3f (0.0, 1.0, 1.0);
    glRectf ( 0.0, 0.0, 1.0, 1.0);
    glPopName ();
glPushName (2);
glColor3f (1.0, 0.0, 1.0);
glRectf ( -1.0, -1.0, 0.0, 0.0);
glPopName ();
// TEST END ***********************

glMatrixMode(GL_PROJECTION);			// Restore the projection matrix

hits = glRenderMode(GL_RENDER);
if (hits > 0) TRACE("HIT FOUND


Thx in advance

I think i can specify my problem.
When i trace the viewport array i get
values about: -858993460 for all 4 entries

how can this happen when i write:
glGetIntegerv(GL_VIEWPORT, viewport);
TRACE("viewport =%i, %i, %i, %i

Do i need to create a viewport ?
And how ?

Please help

Not sure of your problem, but here are some things to try:

[ul][]Make sure you’ve got a valid rendering context. I’m assuming you do or you wouldn’t be seeing anything drawn[]Make sure you are setting your viewport in your resize function with glViewport. It seems strange that glGetInteger would return the values you are seeing.[]Alternately, you could just save the viewport settings on your own in the resize rather than getting them with glGetInteger[]Make sure that what you are drawing in the selection buffer has the same transformations as what you are drawing in the scene.[/ul]

I forgot the rendering content.