通过opengl（MFC）拖动图像

Question

I am using an openGL to drag an image (loaded bitmap) and wondering if there some methods/function to transform the image on the screen.

so far i have done this code to load an image:

void CDisplayControlPanelView::OnDraw(CDC* /*pDC*/)
{
    CDisplayControlPanelDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    if(!pDoc)
        return;

    wglMakeCurrent(m_hDC , m_hRC);
    RenderScene();
    SwapBuffers(m_hDC);
    wglMakeCurrent(m_hDC,NULL);
}

void CDisplayControlPanelView::RenderScene()
{
    AUX_RGBImageRec* pRGBImage;

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glClearColor(0.0, 0.0, 0.0, 0.0);

    glClear(GL_COLOR_BUFFER_BIT);
    pRGBImage = auxDIBImageLoadA("D:\\map.bmp");

    glDrawPixels(pRGBImage->sizeX, pRGBImage->sizeY, GL_RGB, GL_UNSIGNED_BYTE, pRGBImage->data);
    glFlush();
}

Answer 1

Use glTranslate . There are many other ways but this is the most simple. Check out some tutorials if you are new to OpenGL, it could help.

Answer 2

The first thing you must understand is, that OpenGL is not a scene graph. It's a drawing API, very much like Windows GDI. The function glDrawPixels is not very unlike a BitBlt from a MemDC.

Anyway: You shouldn't use glDrawPixels. It's slow and deprecated. The way to draw images in OpenGL is uploading the image into a texture and drawing a textured quad. The quad you can freely move around as you like.