HELP! Window can't RePaint fast enough.

[vulcan_146]

I decided to make a simple Ray-Casting Engine. Right now all you can do is press the LEFT Arrow Key to turn left, however, the window can't seem to refresh fast enough and there is thus terrible clipping. Suggestions?

#include <windows.h>
#include <math.h>
#include <iostream.h>

#define PI 3.14159265358979323846

int map[10][10] = {
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 0, 0, 0, 0, 0, 0, 0, 0, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1
	};

CONST int PlayerHeight = 32;
CONST int WallHeight = 64;
CONST double DegreeChange = 60.0/320.0;
CONST int DistanceToProjection = 277;

int PlayerAngle = 45;

double Distance(double, double, double);

HWND hWnd;
const char ClsName[] = "Ray-Casting Test";
const char WindowCaption[] = "Ray-Casting Test";
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam);

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine, int nCmdShow)
{
    MSG         Msg;
    WNDCLASSEX  WndClsEx;

    WndClsEx.cbSize        = sizeof(WNDCLASSEX);
    WndClsEx.style         = CS_HREDRAW | CS_VREDRAW;
    WndClsEx.lpfnWndProc   = WndProc;
    WndClsEx.cbClsExtra    = NULL;
    WndClsEx.cbWndExtra    = NULL;
    WndClsEx.hInstance     = hInstance;
    WndClsEx.hIcon         = LoadIcon(hInstance, IDI_APPLICATION);
    WndClsEx.hCursor       = LoadCursor(NULL, IDC_ARROW);
    WndClsEx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    WndClsEx.lpszMenuName  = NULL;
    WndClsEx.lpszClassName = ClsName;
    WndClsEx.hIconSm       = LoadIcon(hInstance, IDI_APPLICATION);

    RegisterClassEx(&WndClsEx);

    hWnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW,
                          ClsName,
                          WindowCaption,
                          WS_OVERLAPPEDWINDOW,
                          100,
                          120,
                          320,
                          200,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    while( GetMessage(&Msg, NULL, 0, 0) )
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    return Msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
    HDC hDC;
    PAINTSTRUCT Ps;
    COLORREF Red = RGB(255, 0, 0);
    COLORREF Green = RGB(0, 255, 0);
    COLORREF Blue  = RGB(0 ,0, 255);
    HPEN RedPen = CreatePen(PS_SOLID, 0, Red);
    HPEN GreenPen = CreatePen(PS_SOLID, 0, Green);
    HPEN BluePen = CreatePen(PS_SOLID, 0, Blue);

    double y = -30;
    double distance;
    double degrees;
    double height;
    int top;
    int bottom;

    switch(Msg)
    {
    case WM_PAINT:
	hDC = BeginPaint(hWnd, &Ps);
	for (int i = 0; i <= 320; i++) {
		distance = Distance(PlayerAngle + y, 256, 256);
		distance = distance * cos(y*PI/180);
		degrees = atan(32.0/distance) / PI * 180;
		height = tan(degrees*PI/180) * DistanceToProjection;
		SelectObject(hDC, BluePen);
		MoveToEx(hDC, i, 100 + height, NULL);
		LineTo(hDC, i, 100 - height);
		SelectObject(hDC, RedPen);
		MoveToEx(hDC, i, 100 - height, NULL);
		LineTo(hDC, i, 0);
		y = y + DegreeChange;
	}
	EndPaint(hWnd, &Ps);
	break;
    case WM_DESTROY:
        PostQuitMessage(WM_QUIT);
        break;
    case WM_KEYDOWN:
	if (wParam == VK_LEFT) {
		PlayerAngle = PlayerAngle - 5;
		InvalidateRect(hWnd, NULL, TRUE);
		UpdateWindow(hWnd);
	}
	break;
	
    default:
        return DefWindowProc(hWnd, Msg, wParam, lParam);
    }
    return 0;
}


double Distance(double Angle, double PlayerX, double PlayerY) {
	double DistanceChange = 1;
	double Distance = 0;
	double X = PlayerX;
	double Y = PlayerY;
	int i = 0;
	int XCord;
	int YCord;
	double XChange = cos(Angle*PI/180) * 1;
	double YChange = sin(Angle*PI/180) * 1;

	while (i == 0) {
		Distance = Distance + DistanceChange;
		X = X + XChange;
		Y = Y - YChange;

		XCord = floor(X/64);
		YCord = floor(Y/64);

		if (map[XCord][YCord] == 1)
			i = 1;
	}

	return Distance;
}

Distance is a function that traces a ray to a wall and returns the distance.

[Dante Shamest]

What you need is double buffering. I created a buffer device context for you. Perform all your drawing on the buffer device context, then use swapBufferToScreen() to transfer contents in the buffer to the screen.

raytracer.cpp

[vulcan_146]

Thanks! Worked Great!