palib/source/arm9/PA_Mode7.c

#include <PA9.h>
#include <limits.h>

u32 DX, DY;
u16 PA, PB, PC, PD;
s32 center_y, center_x;

u16 PAtemp; // temp value

u8 PA_currentmode;

s32 mode7cam_x, mode7cam_y, mode7cam_z, mode7alpha;
s32 mode7cos, mode7sin;	// temporaries for cos and sin alpha
s16 mode7_distance;

// in mode7.c
M7CAM _m7_cam;
int _m7_horizon = M7_TOP;
BGAFF_EX _m7_bgaff_ex[192];  // affine parameters for each line

/*! \fn void PA_InitMode7(u8 bg_select)
    \brief
         \~english Initialize Mode 7 for a given background. You MUST be in video mode 1 or 2
         \~french Initialise le Mode 7 pour un fond donné. Vous devez etre en mode 1 ou 2 impérativement !
    \param bg_select
         \~english Bg number, 2 in mode 1, 2 or 3 in mode 2
         \~french Numéro du fond. 2 en mode 1, 2 ou 3 en mode 2
*/

void PA_InitMode7(u8 bg_select) {
	mode7cam_x = X0; mode7cam_y = Y0; mode7cam_z = Z0;
	mode7alpha = 0;
	mode7cos = 256; mode7sin = 0;	// temporaries for cos and sin alpha
	mode7_distance = 160;
//PA_StartInt(INT_HBLANK, hbl_mode7);
	irqSet(IRQ_HBLANK, hbl_mode7);
	irqEnable(IRQ_HBLANK);
}




// globals
// DIV:  a 160-LUT with 1/(h+1) ;  h=[0,160> (16.16 FIXEDs)
// g_cc:  sine value for current alpha (24.8 FIXEDs)
// g_ss:  cosine value for current alpha (24.8 FIXEDs)
// M7_D:   the projection plane distance (=160 in our case)
// cam_x, cam_y, cam_z: camera coordinates (24.8 FIXEDs)



u8 m7_distance = 160;

u8 PAcount;

void hbl_mode7(void) {
	u8 screen = 0;
	u8 bg = 3;
	s32 ww, wcc, wss, wxr, wyr;
//	ww= (mode7cam_y*DIV[REG_VCOUNT])>>12;		// .8*.16 /.12 = 20.12
	s16 vc = REG_VCOUNT;

	if (vc > 192) vc = 0;

	ww = (mode7cam_y << 4) / (vc + 1);		// .8*.16 /.12 = 20.12
	wcc = ww * mode7cos >> 5;					// .12*.8 /.5 = 17.15
	wss = ww * mode7sin >> 5;					// .12*.8 /.5 = 17.15
	// NOTE: when you do P * q0
	// - for x-offset (q0_x): >>7, then *120
	// - for y-offset (q0_y): *160, then >>7
	// Bad things happen if you don't.
	// horizontal scale and offset
	wxr = 128 * (wcc >> 7);				// .8
	wyr = (mode7_distance * wss) >> 7;				// .8
	PA_BGXPA(screen, bg) = wcc >> 7;
	PA_BGXX(screen, bg) = mode7cam_x - wxr + wyr;
	// vertical scale and offset
	wxr = 128 * (wss >> 7);				// .8
	wyr = (mode7_distance * wcc) >> 7;				// .8
	PA_BGXPC(screen, bg) = wss >> 7;
	PA_BGXY(screen, bg) = mode7cam_z - wxr - wyr;
	// REG_IF = INT_HBLANK;		// cleared by isr switchblock
}


#define PA_INT_MIN 0
#define PA_INT_MAX 2147483647

void m7_horz_calc(void) {
	if (_m7_cam.v.y != 0) {
		_m7_horizon = M7_FAR_BG * _m7_cam.w.y - _m7_cam.pos.y;
		_m7_horizon = M7_TOP - swiDivide(_m7_horizon << M7_D_SH, M7_FAR_BG * _m7_cam.v.y);
//        _m7_horizon= M7_TOP - swiDivide(horz<<M7_D_SH, M7_FAR_BG*_m7_cam.v.y);
	} else
		_m7_horizon = _m7_cam.w.y > 0 ? PA_INT_MIN : PA_INT_MAX;
}


/*
typedef struct {
	s16 pa, pb, pc, pd; s32 dx, dy;
} BGAFF_EX;
*/
/*#define PA_BGXX(screen, bg) _REG32(0x4000008 + (0x1000 * screen) + (bg << 4))
#define PA_BGXY(screen, bg) _REG32(0x400000C + (0x1000 * screen) + (bg << 4))
#define PA_BGXPA(screen, bg) _REG16(0x4000000 + (0x1000 * screen) + (bg << 4))
#define PA_BGXPB(screen, bg) _REG16(0x4000002 + (0x1000 * screen) + (bg << 4))
#define PA_BGXPC(screen, bg) _REG16(0x4000004 + (0x1000 * screen) + (bg << 4))
#define PA_BGXPD(screen, bg) _REG16(0x4000006 + (0x1000 * screen) + (bg << 4))
*/
void m7_hbl_flr(void) {
	u8 screen = 0;
	u8 bg = 3;
	u32 vc = REG_VCOUNT;
	// Copie les trucs de BGAFF_EX
	PA_BGXPA(screen, bg) = _m7_bgaff_ex[vc].pa;
	PA_BGXPB(screen, bg) = _m7_bgaff_ex[vc].pb;
	PA_BGXPC(screen, bg) = _m7_bgaff_ex[vc].pc;
	PA_BGXPD(screen, bg) = _m7_bgaff_ex[vc].pd;
	PA_BGXX(screen, bg) = _m7_bgaff_ex[vc].dx;
	PA_BGXY(screen, bg) = _m7_bgaff_ex[vc].dy;
	//bga_ex_mem[2] = _m7_bgaff_ex[vc];
	// Faire le blending...
	//vid_bld_y( _m7_bgaff_ex[vc].pb>>6 );
}



void m7_aff_calc(void) {
	if (_m7_horizon >= 192)
		return;

	int ii, ii0 = _m7_horizon >= 0 ? _m7_horizon : 0;
	s32 dcx = _m7_cam.v.x, dcy = _m7_cam.v.y, dcz = _m7_cam.v.z;
	s32 lam = INT_MAX, cx, cy, cz;
	// initial offsets
	cx = (_m7_cam.w.x << M7_D_SH) + (ii0 - M7_TOP) * dcx;
	cy = (_m7_cam.w.y << M7_D_SH) + (ii0 - M7_TOP) * dcy;
	cz = (_m7_cam.w.z << M7_D_SH) + (ii0 - M7_TOP) * dcz;
	BGAFF_EX *bga = &_m7_bgaff_ex[ii0];

	for (ii = ii0; ii < 192; ii++) {
		if (cy == 0) lam = INT_MAX;
		else lam = swiDivide(_m7_cam.pos.y << 12, cy); // .12

		// a little hack
		bga->pb = lam >> 4;      // .8
		// calculate affine parameters
		bga->pa = (lam * _m7_cam.u.x) >> 12;
		bga->dx = _m7_cam.pos.x + M7_LEFT * bga->pa - (lam * cx >> 12);
		bga->pc = (lam * _m7_cam.u.z) >> 12;
		bga->dy = _m7_cam.pos.z + M7_LEFT * bga->pc - (lam * cz >> 12);
		cx += dcx;      cy += dcy;      cz += dcz;
		bga++;
	}
}