projectionCenter does not affect PerspectiveProjection

programming flash
1

Complex question for hard core 3D programmers !

I am manually drawing 3D lines on screens. I am NOT using the native X Y Z properties of Sprite.
private var displayCoordinates:Vector.<Number> = new Vector.<Number>;
private var displayMatrix:Matrix3D = new Matrix3D();
var pp:PerspectiveProjection = new PerspectiveProjection();

        pp.projectionCenter = new Point(sizeX/2,sizeY/2);
        displayMatrix = pp.toMatrix3D();

        Utils3D.projectVectors(displayMatrix, worldVertices, displayCoordinates,uvts);

// draw on screen based displaycoordinates

No matter what values I put in pp.projectionCenter the Lines always center towards 0,0.

Put another way projectionCenterdoes not change the return value of pp.toMatrix3D()…ever;

I can manually correct this by looping over displayCoordinates and adding the X/2 and Y/2 but seems that I’m missing something important.

Any clues?

Stéphane