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Keyboard input

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Twisol

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With the help of some of the folks on IRC, I finally got some basic user input working. And it doesn't hog the CPU, either! I think the code speaks better than I can this time.


bool Game::Update(INPUT_RECORD* records, DWORD numEvents)
{
bool retval = false;
for (DWORD i = 0; i < numEvents; ++i)
{
if (records.EventType == KEY_EVENT)
{
if (records.Event.KeyEvent.bKeyDown)
{
switch (records.Event.KeyEvent.wVirtualKeyCode)
{
case VK_UP:
retval = true; y -= 1; break;
case VK_DOWN:
retval = true; y += 1; break;
case VK_LEFT:
retval = true; x -= 1; break;
case VK_RIGHT:
retval = true; x += 1; break;
}
}

keypress[records.Event.KeyEvent.wVirtualKeyCode] = (records.Event.KeyEvent.bKeyDown != 0);
}
}
return retval;
}

int Game::Run()
{
Draw();

INPUT_RECORD* records = new INPUT_RECORD[1];
DWORD numEvents = 1;
bool redraw = false;

while (ReadConsoleInput(hIn, records, numEvents, &numEvents))
{
redraw = Update(records, numEvents);

if (keypress[VK_ESCAPE])
break;

if (redraw)
{
Draw();
redraw = false;
}

GetNumberOfConsoleInputEvents(hIn, &numEvents);
if (numEvents)
{
delete[] records;
records = new INPUT_RECORD[numEvents];
}
}
delete[] records;

return 0;
}



It's very basic right now, but most of that is going to go into that Keyboard class I mentioned (currently not being used). While I was working this out, I was using a while (true) loop. That turned out to be a very bad idea, because when I opened up the Task Manager, Cripes was sucking up almost 20% of my CPU time. I figured this version out, luckily, which uses far less CPU time because ReadConsoleInput() blocks when there's no input in the buffer.

This code will definitely be changing, mostly as I move code into the Keyboard class and start utilizing it in Run(). For now I'm just glad I can kinda-sorta move the map around. :P

~Jonathan
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Well, just changing it from while (true) to while (GetConsoleInpt(...)) fixed the CPU problem, so I'm just going by logic and evidence.

EDIT: Here's the code I was using before.

while (true)
{
if (GetAsyncKeyState(VK_ESCAPE))
break;

GetNumberOfConsoleInputEvents(hIn, &numEvents);
if (numEvents != 0)
{
records = new INPUT_RECORD[numEvents];
ReadConsoleInput(hIn, records, numEvents, &numEvents);
for (DWORD i = 0; i < numEvents; ++i)
{
if (records[i].EventType == KEY_EVENT)
{
redraw = true;
keypress[records[i].Event.KeyEvent.wVirtualKeyCode] = (records[i].Event.KeyEvent.bKeyDown != 0);
}
}
}

if (redraw)
{
Draw();
redraw = false;
}
}



Looking over it again, I see that the problem was that I was continuously looping when there were no events (if (numEvents != 0) { /**/ }). I still think while (GetConsoleInput(...)) is better, and it's a bit harder to make mistakes like this.

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