Path: chuka.playstation.co.uk!scea!greg_labrec@interactive.sony.com
From: justin@digitalcity.com
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Drawing without refresh
Date: Sat, 16 Aug 1997 00:42:08 +0000
Organization: Digital City Inc.
Lines: 149
Message-ID: <33F4F75F.6E8A@digitalcity.com>
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I am working on a simple screen saver type thing. I use GsGline to draw
lines randomly on screen.  I would like to keep all drawn lines on
screen after refresh. So that eventuly the screen will fill up with
multi colored lines. The only thing I can think of is to never redraw
the screen by doing a while loop inside the main loop. I have not tried
this yet but will tonight. Any ideas? Also if you run my code you'll
notice that the background is kinda blue-green.  This is the default
background color of the frame buffer I think.  How do I make my
background black without using a TIM file.

-justin

Source:
_______________________

#include <libps.h>

#define MAXOBJ          1
#define OT_LENGTH       1
#define GO                      0

GsOT            WorldOT[2];
GsOT_TAG        OTTags[2][1<<OT_LENGTH];

PACKET  GpuPacketArea[2][MAXOBJ*(20+4)];

volatile u_char *bb0, *bb1;
int activeBuff;
int frames = 0;

int startx = 0;
int starty = 0;
int endx = 320;
int endy = 240;
int r = 0;
int g = 0;
int b = 0;

u_long run = 1;
int button;
u_long state = 1;

main() {

int i;

SetVideoMode( MODE_NTSC );
GetPadBuf(&bb0, &bb1);

GsInitGraph(320, 240, 4, 0, 0);
GsDefDispBuff(0, 0, 0, 240);

// Init the ordering table
for (i = 0; i < 2; i++) 
        {
        WorldOT[i].length = OT_LENGTH;
        WorldOT[i].org = OTTags[i];
        }

FntLoad(960, 256);
FntOpen(40, 100, 256, 200, 0, 256);

while (run == 1) {

        graphicsInit();
        
        FntPrint("Frames: %d\n\n", frames);

                        DrawLine();
                                
        GsDrawOt(&WorldOT[activeBuff]);
        
        ++frames;
        ++startx;
        ++starty;
        ++r;
        ++g;
        ++b;
        --endx;
        --endy;
        
        if (startx == 320)  
                startx = 0;
        if (starty == 240)
                starty = 0;
        if (endx == 0)
                endx = 320;
        if (endy == 0)
                endy = 240;
        if (r == 255)
                r = 0;
        if (g == 255)
                g = 0;
        if (b == 255)
                b = 0;
                
        FntFlush(-1);

        }
        return(0);
}
        
        /* Line Drawing Function*/
        static int DrawLine()
        {
                GsGLINE Line[2];
                
                Line[0].attribute = 0;
                Line[0].x0 = startx;
                Line[0].y0 = starty;
                Line[0].x1 = endx;
                Line[0].y1 = endy;
                Line[0].r0 = b;
                Line[0].g0 = r;
                Line[0].b0 = g;
                Line[0].r1 = r;
                Line[0].g1 = g;
                Line[0].b1 = b;

                GsSortGLine(&Line[0], &WorldOT[activeBuff], 0);
                
                Line[1].attribute = 0;
                Line[1].x0 = startx;
                Line[1].y0 = starty;
                Line[1].x1 = endx;
                Line[1].y1 = endy;
                Line[1].r0 = b;
                Line[1].g0 = r;
                Line[1].b0 = g;
                Line[1].r1 = r;
                Line[1].g1 = g;
                Line[1].b1 = b;

                GsSortGLine(&Line[1], &WorldOT[activeBuff], 0);
                
                return(0);
        }
        /* Graphics Initialization Function */
        
        static int graphicsInit()
        {
                activeBuff = GsGetActiveBuff();
                GsSetWorkBase((PACKET *)GpuPacketArea[activeBuff]);
                GsClearOt(0, 0, &WorldOT[activeBuff]);
                DrawSync(0);
                VSync(0);
                GsSwapDispBuff();
                GsSortClear(60, 120, 120, &WorldOT[activeBuff]);
        }