// http://math.stackexchange.com/questions/1098487/atan2-faster-approximation
// atan2(y,x)
// a := min (|x|, |y|) / max (|x|, |y|)
// s := a * a
// r := ((-0.0464964749 * s + 0.15931422) * s - 0.327622764) * s * a + a
// if |y| > |x| then r := 1.57079637 - r
// if x < 0 then r := 3.14159274 - r
// if y < 0 then r := -r
sll sllatan2(sll y, sll x) {
sll abs_x = sllabs(x);
sll abs_y = sllabs(y);
sll maxyx = MAX(abs_x, abs_y);
sll minyx = MIN(abs_x, abs_y);
sll a = slldiv(minyx, maxyx);
sll s = sllmul(a, a);
sll r_1 = sllmul(dbl2sll((-0.0464964749)), s);
sll r_2 = slladd(r_1, dbl2sll(0.15931422));
sll r_3 = sllsub(sllmul(r_2, s), dbl2sll(0.327622764));
sll r = slladd(sllmul(sllmul(r_3, s), a), a);
if(sllabs(y) > sllabs(x)) {
r = sllsub(CONST_PI_2, r);
}
if(x < CONST_0) {
r = sllsub(CONST_PI, r);
}
if(y < CONST_0) {
r = sllneg(r);
}
return r;
}
static __inline__ double dbl(double x) {
sll sval = dbl2sll(x);
return *(double*)&sval;
}
void phase2_process(void)
{
sll inc=dbl2sll(0.0022);
phase2_ship_x=128; phase2_ship_y=147;
phase2_shoot.x=0; phase2_shoot.y=0; phase2_shoot.state=100;
phase2_bad.x=0; phase2_bad.y=300; phase2_bad.state=105;
phase2_global_x=0; phase2_global_y=0;
music_play_fade(MUSIC_LEVEL);
init_frame_time();
theend=0;
while (!theend)
{
getKey();
if (hit1_pressed)
if (phase2_shoot.state>=25)
{
sll angle=sllsub(mode7_angle,sllmul(inc,int2sll((128-phase2_ship_x)<<1)));
sll multi=int2sll((256-phase2_ship_y)/24);
phase2_shoot.dx=sllmul(sllrotl(sllcos(angle),3),SLL_CONST_PI);
phase2_shoot.dy=sllmul(sllrotl(sllsin(angle),3),SLL_CONST_PI);
phase2_shoot.x=slladd(mode7_x,sllmul(phase2_shoot.dx,multi));
phase2_shoot.y=slladd(mode7_y,sllmul(phase2_shoot.dy,multi));
angle=sllsub(mode7_angle,sllmul(inc,int2sll((128-phase2_ship_x)<<2)));
phase2_shoot.dx=sllmul(sllrotl(sllcos(angle),3),SLL_CONST_PI);
phase2_shoot.dy=sllmul(sllrotl(sllsin(angle),3),SLL_CONST_PI);
phase2_shoot.alt=(phase2_ship_y-128)>>2;
phase2_shoot.state=24;
play_sound(SND_SHIP_LASER);
}
if (left_pressed)
phase2_ship_x-=8;
else if (right_pressed)
phase2_ship_x+=8;
else if (phase2_ship_x<128)
phase2_ship_x+=4;
else if (phase2_ship_x>128)
phase2_ship_x-=4;
if (phase2_ship_x>=192)
phase2_ship_x-=8;
else if (phase2_ship_x<=64)
phase2_ship_x+=8;
if (up_pressed)
{
if (mode7_z<512)
{
mode7_z += 32;
phase2_ship_y-=8;
}
}
else if (down_pressed)
{
if (mode7_z>256)
{
mode7_z -= 32;
phase2_ship_y+=8;
}
}
else
if (mode7_z>400)
{
mode7_z-=16;
phase2_ship_y+=4;
}
else
if (mode7_z<368)
{
mode7_z+=16;
phase2_ship_y-=4;
}
mode7_process(sllsub(mode7_angle,sllmul(inc,int2sll((128-phase2_ship_x)>>1))));
phase2_global_x= sll2int(mode7_x);
phase2_global_y= sll2int(mode7_y);
phase2_draw();
delay_frame_time();
}
