Updating camera movement with keys not working - c++

Question

I'm having a problem with updating camera's position based on keys pressed. Simply put, I'm trying to get the camera to move LEFT, RIGHT, FORWARD, BACKWARD using the arrow keys. When the program runs, the camera starts in the correct position, furthermore, when a key is pushed, the program registers that the key has been pressed, but the camera doesn't update accordingly.
If anything, I see the problem as the actions aren't being performed within the else statement of the loop (where my gyrating cube resides). My biggest obstacle is to get the value of the key pressed into the loop so I can update the camera position. Any ideas or suggestions as to where to look next?
Here is the code as follows:
Render.cpp
Render *renderDraw = new Render(renderWinWidth, renderWinHeight);
Camera *camera = new Camera();
void Render::renderScreen(Camera *cam)
{
...
gluLookAt(cam->getCameraX(), cam->getCameraY(), cam->getCameraZ(),
objPos[0], objPos[1], objPos[2], VECTOR_UP[0], VECTOR_UP[1], VECTOR_UP[2]);
...
glFlush();
}
Camera.cpp
void Camera::setkeyPressed(WPARAM wParam, HWND hWnd, bool isPressed)
{
keyPressed[wParam] = isPressed;
switch(wParam)
{
case VK_UP:
//MessageBox(hWnd, L"key up", L"Key pressed", MB_OK | MB_ICONASTERISK);
newPos_ = getCameraX();
newPos_ -= 2.0f;
setCameraX(newPos_);
break;
case VK_DOWN:
//MessageBox(hWnd, L"key down", L"Key pressed", MB_OK | MB_ICONASTERISK);
newPos_ = getCameraX();
newPos_ += 2.0f;
setCameraX(newPos_);
break;
case VK_LEFT:
//MessageBox(hWnd, L"key left", L"Key pressed", MB_OK | MB_ICONASTERISK);
newPos_ = getCameraZ();
newPos_ += 2.0f;
setCameraZ(newPos_);
break;
case VK_RIGHT:
//MessageBox(hWnd, L"key right", L"Key pressed", MB_OK | MB_ICONASTERISK);
newPos_ = getCameraZ();
newPos_ -= 2.0f;
setCameraZ(newPos_);
break;
}
}
main.cpp
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
...
// Main Loop
while (isRunning)
{
if (PeekMessage (&msg, hWnd, 0, 0, PM_REMOVE))
{
if (msg.message == WM_QUIT)
isRunning = false;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
renderDraw->renderScreen(camera); <-Contains gyrating cube
SwapBuffers(*hDC);
}
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
....
switch (message)
{
case WM_KEYDOWN:
switch (wParam)
{
camera->setkeyPressed(wParam, hWndChild, true);
break;
}
break;
....
}
}

Answer 1

Are you processing your key events in the while loop? And isn't the while loop getting all the processor time without allowing your application to listen to key presses?
try this and render your scene when you are not listening to keys
while( uMsg.message != WM_QUIT )
{
if( PeekMessage( &uMsg, NULL, 0, 0, PM_REMOVE ) )
{
TranslateMessage( &uMsg );
DispatchMessage( &uMsg );
}
else
render();
}
Look at the directX examples only to see how they process the key events in the messsage loop. The logic should be the same for openGL.

Answer 2

The change in camera position isn't applied until you render your scene, so after you update your camera in Camera::setKeyPressed you need to force a redraw. You should be able to do this by calling InvalidateRect() at the end of ::setkeyPressed