A Very Noob Problem

[notthenewsreader]

Hi Guys

I am extremely sorry for asking this question, but I really am stuck, all I want to do is just create a black screen and have some snowflakes (just pixels) fall down the screen, now I have tried writing this a million times, I've tried with openGL, allegro, GDI amd I just don't know what to do; I can't get it to work properly at all, can someone please help me? If someone could just give me a few lines of code to black the screen and plot pixels at random points, that is all I need - I can do the rest myself, but it just seems inefficient to use a 3D graphics library for something so simple.

Please Help.

Thank you all, I REALLY appreciate it.

[Return 0]

Does it have to be in 3d? Have you tried this using the SDL API? It's fairly simple. You could always post your code for the forum to look at.

[Alan]

I DONT use direct3d since it provides few (that is too many) inaccessable solutions to problems.. (Java may be good for this) if you insist though...

To black the screen:

LPDIRECT3DDEVICE9 d3ddev;    // d3ddev is a valid pointer to the device class

/*
make your window and init D3D
*/

d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

Note: this will not compile... You need to create your window using CreateWindowEx() after filling in the WNDCLASSEX structure. then use ShowWindow() to show it... then use Direct3DCreate9() to set the pointer to d3d.. then fill in the D3DPRESENT_PARAMETERS to set how its displayed (ie. windowed/fullscreen) then use CreateDevice() to create your device class with the information from the d3dpresent structure...

whew... *cough* Java

[guestgulkan]

If it is windows you are using - then the windows API has a SetPixel function.

[notthenewsreader]

Hi guys, thanks for all of your replies, the reason I started doing this is because I am trying to recreate something that was on the Amiga years ago written in C, here's the code:... ok that didn't work, a bit too long

[notthenewsreader]

#include <intuition/intuition.h>
#include <graphics/gfxbase.h>
#include <exec/memory.h>
#include <stdio.h>
#include "myiff.h"
#include <ctype.h>
#define MAXSNOWMASS 200
void *OpenLibrary(),*OpenScreen(),*OpenWindow(),*GetMsg(),*AllocMem();
struct GfxBase *GfxBase;
struct IntuitionBase *IntuitionBase;
struct Screen *s,*bs;
struct Window *w;
struct	NewScreen ns={0,0,320,256,5,1,2,0,CUSTOMSCREEN,0,0,0,0};
struct NewWindow nw={0,0,320,256,-1,-1,CLOSEWINDOW,WINDOWCLOSE|BORDERLESS|
	SMART_REFRESH|NOCAREREFRESH|ACTIVATE,0,0,0,0,0,0,0,0,0,CUSTOMSCREEN};
UWORD BlackColors[32];

OpenAll(filename,backup)
char *filename;
int backup;
{
	long sec,mic;

	if ((GfxBase=OpenLibrary("graphics.library",0L))==0) abort("No gfxbase");
	if ((IntuitionBase=OpenLibrary("intuition.library",0L))==0)
		abort("No intuition");
	CurrentTime(&sec,&mic);
	srand((int)mic);
	if ((LoadPicture(filename))==0) abort("Can't load picture");
	if (backup) 
		BltBitMap(&s->BitMap,0L,0L,&bs->BitMap,0L,0L,(long)s->Width,(long)s->Height,0xC0L,0xFFL,0L);
}

abort(errortext)
char *errortext;
{
	if (errortext!=0) puts(errortext);
	if (w) CloseWindow(w);
	if (bs) CloseScreen(bs);
	if (s) CloseScreen(s);
	if (GfxBase) CloseLibrary(GfxBase);
	if (IntuitionBase) CloseLibrary(IntuitionBase);
	exit(0);
}

LoadPicture(filename)
char *filename;
{
	FILE  	*fd;
	struct	BitMapHeader bmhd;
	long  	formsize;
	UWORD 	*colortable[32],modes;
	
	if (!(fd = fopen (filename, "r")))
		return(0);
	if (GetBMHD(fd,&bmhd,&formsize)==-1)
		return(0);
	if (GetCMap(fd,&formsize,colortable,&modes)==-1)
		return(0);
/* buildupdascreen */
	if (modes==0xffff)
	{
	modes=0;
	if (bmhd.w>452) modes|=HIRES;
	if (bmhd.h>352) modes|=LACE;
	}
	ns.LeftEdge=bmhd.x;
	ns.TopEdge=bmhd.y;
	ns.Width=bmhd.w;
	ns.Height=bmhd.h;
	ns.Depth=bmhd.nplanes;
	ns.ViewModes=modes;
	ns.Type=CUSTOMSCREEN;
	if ((bs=OpenScreen(&ns))==0) abort("Can't open backupscreen");
	if ((s=(struct Screen *)OpenScreen(&ns))==0) abort("No memory for screen");
	LoadRGB4(&s->ViewPort,BlackColors,(long)1<<bmhd.nplanes);
	nw.Screen=s;
	nw.Width=bmhd.w;
	nw.Height=bmhd.h;
	if ((w=(struct Window *)OpenWindow(&nw))==0) abort("No window here");
	if (LoadBitMap(fd,&s->ViewPort,&bmhd)==-1) return(0);
	LoadRGB4(&s->ViewPort,colortable,(long)1<<bmhd.nplanes);
	return(1);
}
GetCMap(fd,formsize,colortable,modes)
FILE *fd;
long *formsize;
UWORD *colortable;
UWORD *modes;
{
	struct ChunkHeader ch;
	register UBYTE *ctable;
	register int i,n;
	ULONG temp=0;

	*modes=0xffff;
	while (*formsize > 0) 
{
		if (!fread (&ch, sizeof (ch), 1, fd))
			return(-1);
		*formsize -= sizeof (ch);

		switch (ch.TYPE)
		{
		case CMAP:
		{
			ctable=(UBYTE *)AllocMem((long)ch.chunksize,0L);
			fread (ctable, (int) ch.chunksize, 1, fd);

			for (i = n = 0; n < ch.chunksize; i++, n+=3)
				colortable[i] = ((ctable[n]>>4 ) << 8) +
					  ((ctable[n+1]>>4 ) << 4) +
					  ( ctable[n+2]>>4 );
			FreeMem(ctable,(long)ch.chunksize);

			break;
		}

		case CAMG:
			fread (&temp, (int) ch.chunksize, 1, fd);
			*modes = (UWORD) (temp & 0xffffffff);
			break;

		case BODY:
			return(0);
			break;

		case CRNG:
		case GRAB:
		case SPRT:
		case DPPV:	/*  Anyone know what this one is for?  */
		case DPPS:	/*  Anyone know what this one is for?  */
			fseek (fd, ch.chunksize, 1);
			break;

		default:
			printf("unrecognized chunk 0x%lx\n",ch.TYPE);
			fseek (fd, ch.chunksize, 1);
		}

		*formsize -= ch.chunksize;
		if (ch.chunksize & 1)		/*  Odd length chunk  */
		{
			*formsize --;
			fseek (fd, 1L, 1);
		}
	}
	return(-1);
}
GetBMHD(fd,bmhd,formsize)
FILE *fd;
struct BitMapHeader *bmhd;
long *formsize;
{
	long subtype;
	struct ChunkHeader ch;
	if (!fread (&ch, sizeof (ch), 1, fd))
	{
		return(-1);
	}
	
	if (ch.TYPE != FORM)
	{
		return(-1);
	}
	*formsize=ch.chunksize;

	if (!fread (&subtype, sizeof (subtype), 1, fd))
		return (-1);
	*formsize -= sizeof (subtype);
	if (subtype != ILBM)
		return(-1);
	if (!fread (&ch, sizeof (ch), 1, fd))
		return(-1);
	*formsize -= sizeof (ch);

	fread (bmhd, (int) ch.chunksize, 1, fd);

	*formsize -= ch.chunksize;
	return(0);
}

/* This routine is a fairly direct copy from Leo Schwab's Yaiffr - tanx */

LoadBitMap (fd, vp, header)
FILE *fd;
struct ViewPort *vp;
struct BitMapHeader *header;
{
	register struct BitMap	*bm;
	register int		i, n;
	long			plane_offset = 0;

	bm = vp -> RasInfo -> BitMap;

	if (header->Compression != cmpNone &&
	    header->Compression != cmpByteRun1)
		return(-1);

	for (i=0; i < bm->Rows; i++) {
		for (n=0; n < bm->Depth; n++) {
/*- - - - - - - - - - -*/
if (!header->Compression) {	/* No compression */
	if (!fread (bm -> Planes[n] + plane_offset,
		    bm -> BytesPerRow, 1, fd))
		return(-1);

} else {
	int		so_far;
	register UBYTE	*dest = bm -> Planes[n] + plane_offset;
	char		len;

	/*
	 * Note:  All file I/O after this point is assumed to be sucessful.
	 * This is clearly a poor assumption, but it saves on typing.
	 * And besides, putting the checking in is simple :-) :-).
	 */
	so_far = bm -> BytesPerRow;
	while (so_far > 0) {
		if ((len = getc (fd)) >= 0) {	/*  Literal byte copy  */
			so_far -= ++len;
			if (!fread (dest, len, 1, fd)) return(-1);
			dest += len;

		} else if ( len == -128)	/*  NOP  */
			;

		else if (len < 0) {		/*  Replication count  */
			UBYTE	byte;

			len = -len + 1;
			so_far -= len;
			byte = getc (fd);
			while (--len >= 0)
				*dest++ = byte;
		}
	}
	if (so_far)
		return(-1);
}
/*- - - - - - - - - - -*/
		}
		plane_offset += bm -> BytesPerRow;
	}
	return(0);
}

DoSnow(mass,refresh,wind)
long mass,refresh,wind;
{
	struct IntuiMessage *msg;
	register long cx,cy,i,end,oldx,*x,*y,timer;
	
	timer=refresh;
	x=AllocMem(800L,0L);
	y=AllocMem(800L,0L);
	if (mass>MAXSNOWMASS) mass=MAXSNOWMASS;
	for (i=0;i<mass;i++) y[i]=-(rand()%w->Height);
	while ((msg=GetMsg(w->UserPort))==0)
	{
		if (refresh!=-1)
		{
			if (--refresh==0)
			{
				for (i=0;i<mass;i++)
					*(bs->BitMap.Planes[0]+(s->Width/8)*y[i]+x[i]/8) |= (128>>(x[i]%8));
				BltBitMap(&bs->BitMap,0L,0L,&s->BitMap,0L,0L,(long)s->Width,(long)s->Height,0xC0L,0xFFL,0x00L);
				for (i=0;i<mass;i++)
					*(bs->BitMap.Planes[0]+(s->Width/8)*y[i]+x[i]/8) &= ~(128>>(x[i]%8));
				refresh=timer;
			}
		}
		for (i=0;i<mass;i++)
		{
			if (y[i]<-1) y[i]++;
			else
			{
				cx=x[i];
				cy=y[i];
				if (cy==-1) {cy=0;cx=rand()%w->Width;}
				else
				{
					oldx=cx;
					cx+=(rand()%31-wind-15)/8;
					if (cx>s->Width-1) cx-=s->Width;
					if (cx<0) cx+=s->Width;
					if (ReadPixel(w->RPort,cx,cy+1)==0)
					{
						*(s->BitMap.Planes[0]+(s->Width/8)*cy+oldx/8)&=~(128>>(oldx%8));
						cy++;
						*(s->BitMap.Planes[0]+(s->Width/8)*cy+cx/8) |= (128>>(cx%8));
					}
					else
					{
						end=1;
						if ((ReadPixel(w->RPort,cx+1,cy+1)==0)&&
							(ReadPixel(w->RPort,cx-1,cy+1)==0))
						{
							if ((cx>0)&&(rand()%2==1)) cx--;
							else if (cx<w->Width-1) cx++;
								else cx--;
							end=0;
						}
						if ((ReadPixel(w->RPort,cx+1,cy+1)==0)&&(end==1)/* &&(rand()%6!=1) */)
							{cx++; end=0;}
						if ((ReadPixel(w->RPort,cx-1,cy+1)==0)&&(end==1)/* &&(rand()%6!=1) */)
							{cx--; end=0;}
						if (end==0)
						{
							*(s->BitMap.Planes[0]+(s->Width/8)*cy+oldx/8)&=~(128>>(oldx%8));
							cy++;
						}
						*(s->BitMap.Planes[0]+(s->Width/8)*cy+cx/8) |= (128>>(cx%8));
						if (end==1) cy=-1;
					}
				}
				x[i]=cx;
				y[i]=cy;
			}
		}
	}
	FreeMem(x,800L);
	FreeMem(y,800L);
}

DisplayUsage()
{
	puts("Snowfall - made December 1989 by Lars R. Clausen");
	puts("Usage: SnowFall [-ppicture] [-n#snowflakes] [-trefreshtime] [-wwindforce]");
	exit(0);
}

main(argc,argv)
int argc;
char **argv;
{
	char file[100];
	int number=40,refresh=10000,i,wind=0;

	if ((argc==2)&&(strcmp(argv[1],"?")==0)) DisplayUsage();

	strcpy(file,"SnowPic");
	for (i=1;i<argc;i++)
	{
		if (argv[i][0]=='-')
			switch (argv[i][1])
			{
	case 'p': strcpy(file,&argv[i][2]); break;
	case 'n': number=atoi(&argv[i][2]); break;
	case 't': refresh=atoi(&argv[i][2]); break;
	case 'w': wind=atoi(&argv[i][2]); break;
	default: DisplayUsage();
		}
		else DisplayUsage();
	}
	if (refresh>-1) OpenAll(file,1);
	else OpenAll(file,0);
	DoSnow((long)number,(long)refresh,(long)wind);
	abort(0);
}

[notthenewsreader]

wow, sorry everybody - I never realised it was that long, here's the link incase

http://se.aminet.net/pub/aminet/game/gag/SnowFall.lha

[guestgulkan]

You can tell that is old code - it uses K+R style function layout.

[notthenewsreader]

well I'm still pretty new to C++ so I don't really know the difference, but yeah this is from about 1998 I think, good at the time though and I've spent about the last 3 months trying to get something similar to happen in C++ so I'm at a bit of a loss

[R0mai]

puts("Snowfall - made December 1989 by Lars R. Clausen");

So I guess it's from 1989.