GL_BLEND problem

Hello,

I am trying to draw a cloud of points, however I am having some problems when I enable blending.

Here is the relevant code:


	
        glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);                                             
        
        glDisable(GL_LIGHTING);                                                                        
        glEnable(GL_BLEND);
        glEnable(GL_POINT_SMOOTH); 
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);                                             
        glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);              


	gluPerspective(fovAngle/2.0,aspect,nearPlane,farPlane);
        glMatrixMode(GL_MODELVIEW);

        gluLookAt(origin[0],origin[1],origin[2],
                                target[0],target[1],target[2],
                                upDirection[0],upDirection[1],upDirection[2]);



        const Point3D *p; 
        glPointSize(size); 
        glBegin(GL_POINTS);
                glColor4f(r,g,b,a);
                for(unsigned int ui=0; ui<pts.size(); ui++)
                {   
                        p=&(pts[ui]);
                        glVertex3f((*p)[0],(*p)[1],(*p)[2]);
                }   
        glEnd();
}

This results in the following images.
Left:

Centre:

Right:

Note there is a sphere drawn in using gluSphere to show that lighting is actually disabled (see how it appears up as a circle).

If I remove glEnable(GL_BLEND), then the points have the correct apparent intensity (ie, all have the same intensity, independant of viewing angle). This is good, but the points are blocky, which is what I was trying to solve in the first place.

What is going on? I cannot see where any lighting calculations can come into play if I have disabled lighting completely. I don’t know what effect can be causing this view angle dependency!

Any help is greatly appreciated

OH. never mind. I worked it out a few minutes later. This had been bothering me for days :o

I had the points ordered along the cylinder axis, which meant that the blend result was different for a back-to-front versus a front-to-back ordering