Drawing pixels on a window?

[Devils Child]

hi!
i want to make a software-renderer, like the one i did before in an other programming language. this time, i'll do it in C++. the problem is: how do i draw pixels on the window (FAST) ?
something like a pointer to the screen buffer would be nice
thanks for helping.

#include <windows.h>

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int iCmdShow)
{
	WNDCLASS wc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);
	wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wc.hInstance = hInstance;
	wc.lpfnWndProc = WndProc;
	wc.lpszClassName = TEXT("MainWindow");
	wc.lpszMenuName = 0;
	wc.style = CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&wc);

	HWND hwnd = CreateWindow(
		TEXT("MainWindow"),
		TEXT("Test"),
		WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX,
		100, 100,
		640, 480,
		NULL, NULL,
		hInstance, NULL
	);
	ShowWindow(hwnd, iCmdShow);

	MSG msg;
	while (GetMessage(&msg, NULL, 0, 0 ))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam)
{
	switch (message)
	{
		case WM_PAINT:
			HDC hdc;
			PAINTSTRUCT ps;
			hdc = BeginPaint(hwnd, &ps);
			for (int y = 0; y < 480; y++)
			{
				for (int x = 0; x < 640; x++)
				{
					SetPixel(hdc, x, y, 0xffffff);
				}
			}
			EndPaint(hwnd, &ps);
			break;
		case WM_DESTROY:
			PostQuitMessage(0);
			break;
	}
	return DefWindowProc(hwnd, message, wparam, lparam);
}

[matsp]

The simple solution for "pointer to the frame buffer" is to do double-buffered drawing, where you use the BitBlt function to copy your pixels to the actual screen. So, create yourself a piece of memory big enough to hold all your pixels, then draw to your hearts content with a pointer to that memory, and when you are done, use BitBlt() to copy it in the "WM_PAINT" section.

--
Mats

[Devils Child]

sounds like what i needed. i have an array with a pointer now, and how exactly do i handle the BitBlt() function now?

[matsp]

Let Me Google that for you.

You want the second hit.

--
Mats

[Devils Child]

lol. i already discovered this function, but there is no argument where i can give my pointer to the screen buffer array??

[matsp]

Ok, so you need to CreatCompatibleBitmap(), and then use SetDIBits(), using the address of your pixels, and then use the handle from CreateCompatibleBitmap() to do the actual BitBlt() operation.

--
Mats

[Devils Child]

do you have any example for that?
forgive my dumbness

[matsp]

do you have any example for that?
forgive my dumbness

No, I'm just reading the MSDN web-site and some basic understanding of GDI in general (I did two years of writing Windows graphics device drivers).

This seems like it's in the right general direction: http://www.winprog.org/tutorial/bitmaps.html

--
Mats

[Devils Child]

and how do i access the memory?
although, i thought you'd use a surface instead of a 'bitmap'?

[EVOEx]

Is it me or is setting everything pixel per pixel still going to be excruciatingly slow? I think best is to avoid that while you can. And with what you're doing, drawing a square, I bet it's possible without setting it pixel per pixel. Although I've never done windows api coding...

[Devils Child]

fine. programming a software renderer requires setting everything pixel-per-pixel.
and believe me: it's not slow!

so how do i do it now?

[matsp]

Using SetDIBits, you can set a Bitmap to point to memory that you have allocated.

--
Mats

[Devils Child]

alright. got it now working
thx a lot!