betterrgbquad.cpp

#include <windows.h>
typedef union _RGBQUAD {
	COLORREF rgb;
	struct {
		BYTE b;
		BYTE g;
		BYTE r;
		BYTE unused;
	};
} *PRGBQUAD;

DWORD WINAPI shader1(LPVOID lpParam) {
    int w = GetSystemMetrics(0), h = GetSystemMetrics(1);
    _RGBQUAD* data = (_RGBQUAD*)VirtualAlloc(0, (w * h + w) * sizeof(_RGBQUAD), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    for (int i = 0;; i++, i %= 3) {
        HDC desk = GetDC(NULL);
        HDC hdcdc = CreateCompatibleDC(desk);
        HBITMAP hbm = CreateBitmap(w, h, 1, 32, data);
        SelectObject(hdcdc, hbm);
	BitBlt(hdcdc, 0, 0, w, h, desk, 0, 0, SRCCOPY);
        GetBitmapBits(hbm, w * h * 4, data);
        for (int i = 0; w * h > i; i++) {
		int x = i % w, y = i / h, t = y ^ y | x;
		data[i].rgb = x & y & t;
        }
        SetBitmapBits(hbm, w * h * 4, data);
        BitBlt(desk, 0, 0, w, h, hdcdc, 0, 0, SRCCOPY);
        DeleteObject(hbm);
        DeleteObject(hdcdc);
        DeleteObject(desk);
    }
    return 0;
} 

int main() {
    CreateThread(0, 0, shader1, 0, 0, 0);
    Sleep(-1);
}