* mt.c: Added (Mersenne Twister random number generator).

[vor.git] / dust.c

diff --git a/dust.c b/dust.c
new file mode 100644 (file)
index 0000000..691649d
--- /dev/null
+++ b/dust.c
@@ -0,0 +1,51 @@
+#include <SDL.h>
+#include <math.h>
+
+#include "config.h"
+#include "globals.h"
+#include "dust.h"
+#include "mt.h"
+
+struct dust_mote {
+       float x,y,z;
+       Uint16 color;
+};
+
+struct dust_mote motes[N_DUST_MOTES];
+
+void
+init_dust(void)
+{
+       int i, b;
+       for(i=0; i<N_DUST_MOTES; i++) {
+               motes[i].x = frnd()*(XSIZE-5);
+               motes[i].y = frnd()*(YSIZE-5);
+               motes[i].z = MAX_DUST_DEPTH*sqrt(frnd());
+               b = (MAX_DUST_DEPTH - motes[i].z) * 255.0 / MAX_DUST_DEPTH;
+               motes[i].color = SDL_MapRGB(surf_screen->format, b, b, b);
+       }
+}
+
+void
+move_dust(void)
+{
+       int i;
+       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].y >= XSIZE) motes[i].x -= XSIZE;
+               else if(motes[i].x < 0) motes[i].x += XSIZE;
+               if(motes[i].y > YSIZE) motes[i].y -= YSIZE;
+               else if(motes[i].y < 0) motes[i].y += YSIZE;
+       }
+}
+
+void
+draw_dust(SDL_Surface *s)
+{
+       int i;
+       uint16_t *pixels = s->pixels;
+       for(i=0; i<N_DUST_MOTES; i++) {
+               pixels[s->pitch/2*(int)motes[i].y + (int)motes[i].x] = motes[i].color;
+       }
+}