// Header file for my PSX sprite implementation
// Coded by Scott Evans 11/5/97
// Last modified 14/5/97

#ifndef _MYSPR_H
#define _MYSPR_H

#include <mytypes.h>
#include <timer.h>

// Sprite header file structure

typedef struct
{
	_word nspr;			// Number of sprites in file
	_word npal;			// Number of palettes in file
	_long paloff;			// Offset in bytes from start of file to CLUT data
	_long pblkoff;			// Offset to 1st sprite parameter block
}SprHeader;

// Sprite parameter block structure

typedef struct
{
	_byte w,h;			// Width and height of sprite in pixels
	_word CLUTid;			// CLUT number used by this sprite
	_long imgoff;			// Offset (from start of parameter block) to sprite image data
}SprPblk;

// Sizes of above structures

#define _SprHeaderSize	(sizeof(SprHeader))
#define _SprPblkSize	(sizeof(SprPblk))
#define _4bitCLUTSIZE	32

// Gives offsets into texture page for correct sprite frame

typedef struct
{
	_byte u,v;			// texture page offsets in pixels
	_word pad;			// padding
}SprImgOff;

// Structure whilch gives various info. about sprite

typedef struct
{ 
	_byte *animstr;	// Animation string, list of frames to cycle through
	_byte maxfrms;		// Maximum frames in animation string
	_byte currfrm;		// Current frame of animation
	_byte on;			// Is sprite active
	_byte animon;		// Activate animation
	_byte dying;		// Sprite is being killed
	__byte xspd;		// Horizontal speed of sprite
	__byte yspd;		// Vertical speed of sprite
	GsSPRITE *spr;	
}SprINFO;

#define ON		1
#define OFF		0

// Macro to set members of a SprINFO structure

#define _SetSprINFO(S,A,M,C,O,N,K,X,Y,P) \
	(S)->animstr=(A),(S)->maxfrms=(M),(S)->currfrm=(C),(S)->on=(O),\
	(S)->animon=(N),(S)->dying=(K),(S)->xspd=(X),(S)->yspd=(Y),(S)->spr=(P)

// Find number of sprites
// H is pointer to a SprHeader structure

#define _GetNoSpr(H)	(H->nspr)

// Find address of 1st CLUT

#define _GetCLUT(H)	((_byte *)H+H->paloff)

// Find address of 1st parameter block

#define _GetSprPblks(H)	((SprPblk *)((_byte *)H+H->pblkoff))

// Find address of nth parameter block

#define _GetSprPblk(H,N)	(_GetSprPblks(H)+(N))

// Find sprite width and height

#define _GetSprW(P)		(P->w)
#define _GetSprh(P)		(P->h)

// Find address of sprites image data

#define _GetSprImgData(P)	((_byte *)P+P->imgoff)

#define _GetSprCLUTy(H,N,Y)	(_GetSprPblk(H,N)->CLUTid+Y)
	
// Load palettes from a sprite file into frame buffer
// Parameters : address of sprite file, location of 1st CLUT in frame buffer

void Load4bitCLUT(SprHeader *hdr,_word x,_word y)
{
	_byte i;
	RECT r;
	
	setRECT(&r,x,y,16,1);
	for(i=0;i<hdr->npal;i++)
	{
		LoadImage(&r,(_long *)((_byte *)_GetCLUT(hdr)+_4bitCLUTSIZE*i));
		r.y++;
	}
}

// Load sprites into a texture page
// Parameters : address of paremeter blocks, number of sprites, texture page coordinates,
//			 buffer to store tpage offsets for each image
// Returns    : number of sprites actually loaded

_word LoadSprites(SprPblk *pblk,_word n,_word *tx,_word *ty,SprImgOff *frames)
{
	static _word x=0,y=0;
	_word i;
	_byte sprw,sprh;
	static _byte maxh=0;
	RECT r;
	
	// Make sure texture page is on correct boundary

	*tx=(*tx>>5)<<5;
	*ty=(*ty>>7)<<7;
	
	// Try and load n sprites into frame buffer
	
	for(i=0;i<n;i++,pblk++,frames++)
	{
		// Width and height of sprites
		
		sprw=pblk->w;
		maxh=((sprh=pblk->h)>maxh ? sprh : maxh);
		
		// Fit in as many sprites per row as possible
		
		if(!(x+sprw>TPWDTH ? (y+maxh>TPHGHT ? 0 : (x=0,y+=maxh)) : 1))
		{
			maxh=x=y=0;
			break;
		}
			
		// Store offsets
			
		frames->u=x;
		frames->v=y;
		
		// Image data to frame buffer
		
		setRECT(&r,*tx+(x>>2),*ty+y,sprw>>2,sprh);
		x+=sprw;
		LoadImage(&r,(_long *)_GetSprImgData(pblk));
	}

	// Return number of sprites loaded into texture page
	
	return(i);
}

// Animate a sprite
// Parameters : sprite information, texture page offsets, animation speed

void AnimateSprite(SprINFO *info,SprImgOff *offsets,_byte speed)
{
	if(!(TIMER%speed))
	{
			// Cycle through frames in animation string
		
			info->currfrm++;
			info->currfrm%=info->maxfrms;
			
			// Change frame of sprite
			
			info->spr->u=offsets[info->animstr[info->currfrm]].u;
			info->spr->v=offsets[info->animstr[info->currfrm]].v;  
	}
}

#endif