[FIXED] Problems connecting shapes correctly [openGL]

[FIXED] : I wasn’t familiar with the concept of depth-testing, all is fine now!
Ey All!

I have a question; the answer might be obvious since I’m new at OpenGL. I made a simple 3-d game in which a flyer is controlled by two ultrasonic sensors. The problem is in the code that adds the indexes to the mesh I use to create a mountain landscape. http://i60.tinypic.com/2coitxf.png (the problem shows on the right top side of the flyer).
If I use .drawWireframe to draw the mesh, everything is connected correctly ( http://i61.tinypic.com/58cac.png ), but if I use drawfaces, non 3-d shapes are present parralel with the x-axis. So the vertexes& vertices all seem to be correct, but the faces are not perceived correctly. I’m suspecting I have to make a seperate mesh with trianglestrips for each row, and connect the meshes into a whole somehow? I know the problem is in the winding, but I thought the Mesh would take care of this. By now have no clue at what I’m doing haha :wink: So any pointers would be appreciated!

The code that creates the landscape is as follows:

void LandScapeC::setup(){
landScape.setMode(OF_PRIMITIVE_TRIANGLES);
landScape.enableColors();
landScape.enableIndices();
landScape.enableNormals();

    for(int z=0; z<sizeY; z++){
        for(int x=0; x<sizeX; x++){
                float AltitudeY=ofRandom(0,heightM);
            ofVec3f point(x*stretch, AltitudeY,- z*stretch);
            landScape.addVertex(point);
            if(AltitudeY>=snowLine){
            landScape.addColor(ofFloatColor(1.0,1.0,1.0));
        }else if(AltitudeY<10){
            landScape.addColor(ofFloatColor(0,0.6,0));
            }else{
            landScape.addColor(ofFloatColor(0.0,0.8,0.0));
            }
        }
    }
    //triangles
   // for(int i=0;i<(sizeX-1)*(sizeY-1);i++){
        //if(i<(((sizeX-1)*(sizeY-1))*2)){
        int i=0;
        for(int y=0;y<sizeY-1;y++){
                i=y*sizeX;
            for(int x=0;x<sizeX-1;x++){

        landScape.addIndex(i);
        landScape.addIndex(i+sizeX);
        landScape.addIndex(i+sizeX+1);


        landScape.addIndex(i);
        landScape.addIndex(i+1);
        landScape.addIndex(i+sizeX+1);



        i++;
}
}
}
}