struct dust_mote motes[N_DUST_MOTES];
+// lower bound to ensure that we don't lose precision when wrapping.
+static float zero;
+
void
init_dust(void)
{
b = (MAX_DUST_DEPTH - motes[i].z) * 255.0 / MAX_DUST_DEPTH;
motes[i].color = SDL_MapRGB(surf_screen->format, b, b, b);
}
+
+ zero = pow(-10, ceil(log10(XSIZE)) - FLT_DIG);
}
void
-move_dust(void)
+move_dust(float ticks)
{
int i;
- float xscroll = screendx * t_frame;
- float yscroll = screendy * t_frame;
+ float xscroll = screendx * ticks;
+ float yscroll = screendy * ticks;
+
for(i=0; i<N_DUST_MOTES; i++) {
motes[i].x -= xscroll / (1.3 + motes[i].z);
- motes[i].y -= yscroll / (1.3 + motes[i].z);
if(motes[i].x >= XSIZE) motes[i].x -= XSIZE;
- else if(motes[i].x < 0) motes[i].x += XSIZE;
+ else if(motes[i].x < zero) motes[i].x += XSIZE;
+
+ motes[i].y -= yscroll / (1.3 + motes[i].z);
if(motes[i].y >= YSIZE) motes[i].y -= YSIZE;
- else if(motes[i].y < 0) motes[i].y += YSIZE;
+ else if(motes[i].y < zero) motes[i].y += YSIZE;
}
}