#include <libps.h>
#include "pad.h"
#include "invs.h"

#define OT_LENGTH       1
#define FRAME_X         320
#define FRAME_Y         240    
#define WALL_X          (FRAME_X-INV_SIZE)    
#define WALL_Y          (FRAME_Y-INV_SIZE)  
#define NO_OF_SPRITES   42
#define ORIG_ALIEN_X    25
#define ORIG_ALIEN_Y    20
#define INV_SIZE       16
#define GAP             4
#define BULLET_SPEED    4

GsOT		WorldOT[2];
GsOT_TAG	OTTags[2][1<<OT_LENGTH];
PACKET          GpuPacketArea[2][(NO_OF_SPRITES+1)*24];
GsSPRITE        sprt[NO_OF_SPRITES];

volatile u_char *bb0,*bb1;

void init_aliens(void);
void update_aliens(void);
void check_hit(void);
static void init_prim();         
static long pad_read(long n);    
static u_long PadRead(long id);  

u_char up,down,left,right,delay,frame;
char x_vel,y_vel;
u_char bullet_attached=1;
u_int score=0;

main(void)
{
        GsOT     *ot;
        int      i,ix,j,x,x2,y2,key;   
        int      activeBuff;
        GsSPRITE *sp;
        j=1;

        SetVideoMode(MODE_NTSC);
        GetPadBuf(&bb0,&bb1); 
        GsInitGraph(320,240,4,0,0); 
        GsDefDispBuff(0,0,0,240);

        for (i=0;i<2;i++)
                {
                WorldOT[i].length=OT_LENGTH;
                WorldOT[i].org=OTTags[i];
                }
        FntLoad(960,256);
        FntOpen(220,230,80,1,0,30);
        init_prim();
        init_aliens();

while (pad_read(key)!=-1)
        {
        activeBuff=GsGetActiveBuff();
        GsSetWorkBase((PACKET *)GpuPacketArea[activeBuff]);
        GsClearOt(0,0,&WorldOT[activeBuff]);

        update_aliens();
        check_hit();

        for (sp=sprt,i=0;i<NO_OF_SPRITES;i++,sp++)
        {
        if (sp->cy!=0)
        GsSortFastSprite(sp,&WorldOT[activeBuff],0);
        }

        DrawSync(0);    
        VSync(0);
        GsSwapDispBuff();
        GsSortClear(0,0,0,&WorldOT[activeBuff]);
        GsDrawOt(&WorldOT[activeBuff]);
        FntPrint("Score: %d",score);
        FntFlush(-1);
        } 

return(0);
}

static void init_prim()
{
        GsSPRITE        *sp;
        u_short         tpage;
	RECT		rect;
	int		i;

        rect.x=640;
        rect.y=0;
        rect.w=INV_SIZE/4;
        rect.h=INV_SIZE;
        LoadImage(&rect,inv16x16);
        tpage=GetTPage(0,0,640,0);

        for (i=0;i<32;i++)
                {
                rect.x=0;
                rect.y=480+i;
                rect.w=256;
                rect.h=1;
                LoadImage(&rect,invcolor[i]);
                }

        for (sp=sprt,i=0;i<NO_OF_SPRITES;i++,sp++)
                {
                sp->attribute=0;
                sp->w=INV_SIZE;
                sp->h=INV_SIZE;
                sp->tpage=tpage;
                sp->u=0;
                sp->v=0;
                sp->cx=0;
                sp->cy=480+(i%32);
                sp->r=sp->g=sp->b=0xff;
                sp->mx=0;
                sp->my=0;
                sp->scalex=ONE;
                sp->scaley=ONE;
                sp->rotate=0;
	}
}

static long pad_read(long n)
{
        u_long padd=PadRead(1);

        if (padd&PADLleft)
                left=1;
                else
                left=0;
        if (padd&PADLright)
                right=1;
                else
                right=0;
        if (padd&PADLup)
                up=1;
                else
                up=0;
        if (padd&PADLdown)
                down=1; 
                else
                down=0;
        if (padd&PADRdown)
                bullet_attached=0;
        if (padd&PADselect)
                n=-1;
        return(n);
}

static u_long PadRead(long id)
{
        return(~(*(bb0+3)|*(bb0+2)<<8|*(bb1+3)<<16|*(bb1+2)<<24));
}

void init_aliens(void)
        {
        u_int alien_x,alien_y,i;
        GsSPRITE *sp;
        delay=20;
        x_vel=2;
        y_vel=8;
        alien_x=ORIG_ALIEN_X;
        alien_y=ORIG_ALIEN_Y;
        for (sp=sprt,i=0;i<NO_OF_SPRITES-2;i++,sp++)
                {
                sp->x=alien_x;
                sp->y=alien_y;
                alien_x=alien_x+(INV_SIZE+GAP);
                if (i%10==9)
                        {
                        alien_x=ORIG_ALIEN_X;
                        alien_y+=(INV_SIZE+GAP);
                        }
                }
         sp->x=100; /* Player */
         sp->y=200;
         sp->cy=487;
         sp++;
         sp->x=100; /* Bullet */
         sp->y=184;
         sp->cy=482;
         }

void update_aliens(void)
        {
        u_char i,bounce;
        int save_x,save_y;
        GsSPRITE *sp;
        bounce=0;
        frame++;
        if (frame>=delay)
        {
        frame=0;
        for (sp=sprt,i=0;i<NO_OF_SPRITES-2;i++,sp++)
                {
                sp->x+=x_vel;
                if (sp->cy!=0 & (sp->x>=WALL_X | sp->x<=0))
                        bounce=1;
                }
        if (bounce)
                {
                x_vel=-x_vel;
                bounce=0;
                for (sp=sprt,i=0;i<NO_OF_SPRITES-2;i++,sp++)
                        {
                        sp->y+=y_vel;
                        if (sp->cy!=0 &(sp->y>=WALL_Y | sp->y<=0))
                        bounce=1;
                        }
                if (bounce)
                        y_vel=-y_vel;
                }
        }
        sp=sprt+NO_OF_SPRITES-2;   /* This sprite is player sprite! */
        if (left)  sp->x-=2;
        if (sp->x<0) sp->x+=2;

        if (right) sp->x+=2;
        if (sp->x>=WALL_X) sp->x-=2;

        save_x=sp->x;

        if (bullet_attached)
                {
                sp++;
                sp->x=save_x;
                sp->cy=500;
                }
        else
                {
                save_y=sp->y;
                sp++;
                sp->cy=480+(frame%32);
                sp->y-=BULLET_SPEED;
                if (sp->y<=0)
                        {
                        bullet_attached=1;
                        sp->x=save_x;
                        sp->y=save_y-INV_SIZE;
                        }
                }
        }

void check_hit(void)
        {
        int bullet_x,bullet_y,gap_x,gap_y,i;
        GsSPRITE *sp;
        sp=sprt+NO_OF_SPRITES-1; /* This is the bullet */
        bullet_x=sp->x;
        bullet_y=sp->y;
        for (sp=sprt,i=0;i<NO_OF_SPRITES-2;i++,sp++)
                {
                gap_x=(bullet_x-sp->x);
                gap_y=(bullet_y-sp->y);

                if (gap_x>-INV_SIZE && gap_x<INV_SIZE && gap_y>-INV_SIZE && gap_y<INV_SIZE && sp->cy!=0 && bullet_attached==0)
                        {
                        bullet_attached=1;
                        sp->cy=0;
                        sp=sprt+NO_OF_SPRITES-2;
                        bullet_x=sp->x;
                        bullet_y=sp->y-INV_SIZE;
                        sp++;
                        sp->x=bullet_x;
                        sp->y=bullet_y;
                        score++;
                        if (score%(NO_OF_SPRITES-2)==0)
                                {
                                init_aliens();
                                init_prim();
                                }
                        if (delay>1 & (score%2==1))
                                delay--;
                        break;
                        }
                }
        }