Viewport maping issue

[VincentPham]

I have a problem on understanding how view port work. The view port seems mapping wrong but I can’t understand why.
Everything is just fine until I try to mapping the scene to a specific area on a window by using view port.

Let’s check my source code.

void drawScene() {
static Rectf theRect(50, 50, 200, 100);
gl::color(0, 0, 1);
gl::drawSolidTriangle(theRect.getLowerLeft(), theRect.getLowerRight(), theRect.getUpperRight());
gl::color(0, 1, 0);
gl::drawSolidTriangle(theRect.getLowerLeft(), theRect.getUpperLeft(), theRect.getUpperRight());
}

static Rectf windowPort(30, 20, 130, 170);
static Area viewPort(100, 30, 300, 330);

void drawWindow1() {
gl::clear();

// draw the scene
drawScene();

// draw window port area
gl::color(1, 0, 0);
gl::drawStrokedRect(windowPort, 3);

}

void drawWindow2() {
gl::clear();

// clipping by using ortho projection
gl::ScopedProjectionMatrix projectionMatrixScope;
CameraOrtho orthoCam;
orthoCam.setOrtho(windowPort.x1, windowPort.x2, windowPort.y2, windowPort.y1, 1, -1);
gl::setProjectionMatrix(orthoCam.getProjectionMatrix());

// draw the scene
drawScene();

}

void drawWindow3() {
gl::clear();

// draw view port area
gl::color(1, 0, 0);
gl::drawStrokedRect(Rectf(viewPort), 3);

// mapping scene to view port area
gl::ScopedViewport scopeViewPort(viewPort.getUL(), viewPort.getSize());

// clipping by using ortho projection
gl::ScopedProjectionMatrix projectionMatrixScope;
CameraOrtho orthoCam;
orthoCam.setOrtho(windowPort.x1, windowPort.x2, windowPort.y2, windowPort.y1, 1, -1);
gl::setProjectionMatrix(orthoCam.getProjectionMatrix());

drawScene();

}

And the results:

Let see on window 3, the scene is seem mapping wrong place.
Actually, it’s location changes when I resize the window.
Could anyone help me?