games/galaxy: avoid unnecessary calculations

[plan9front.git] / sys / src / games / galaxy / galaxy.c

diff --git a/sys/src/games/galaxy/galaxy.c b/sys/src/games/galaxy/galaxy.c
index d81b341236733cc00531944785eb12b47309b5b1..57f9b7bbba291cbba19b382733d08aff0f2719a0 100644 (file)
--- a/sys/src/games/galaxy/galaxy.c
+++ b/sys/src/games/galaxy/galaxy.c
@@ -171,8 +171,7 @@ drawglxy(void)
 
        draw(screen, screen->r, display->black, 0, ZP);
        for(b = glxy.a; b < glxy.a + glxy.l; b++) {
-               pos.x = b->x / scale + orig.x;
-               pos.y = b->y / scale + orig.y;
+               pos = topoint(b->Vector);
                s = b->size/scale;
                fillellipse(screen, pos, s, s, b->col, ZP);
                if(showv) {
@@ -198,8 +197,7 @@ setsize(Body *b)
        Point pos, d;
        double h;
 
-       pos.x = b->x / scale + orig.x;
-       pos.y = b->y / scale + orig.y;
+       pos = topoint(b->Vector);
        d = subpt(mc->xy, pos);
        h = hypot(d.x, d.y);
        b->size = h == 0 ? scale : h*scale;
@@ -211,18 +209,10 @@ setvel(Body *b)
 {
        Point pos, d;
 
-       pos.x = b->x / scale + orig.x;
-       pos.y = b->y / scale + orig.y;
+       pos = topoint(b->Vector);
        d = subpt(mc->xy, pos);
-       b->v.x = (double)d.x*scale/10;
-       b->v.y = (double)d.y*scale/10;
-}
-
-void
-setpos(Body *b)
-{
-       b->x = (mc->xy.x - orig.x) * scale;
-       b->y = (mc->xy.y - orig.y) * scale;
+       b->v.x = d.x*scale/10;
+       b->v.y = d.y*scale/10;
 }
 
 void
@@ -275,7 +265,6 @@ dobody(void)
        }
 
        b = body();
-       setpos(b);
        setvel(b);
        setsize(b);
        b->col = randcol();
@@ -290,7 +279,7 @@ dobody(void)
                else if(mc->buttons == 5)
                        dovel(b);
                else
-                       setpos(b);
+                       b->Vector = tovector(mc->xy);
        }
 
        CHECKLIM(b, f);
@@ -349,30 +338,41 @@ domove(void)
        setcursor(mc, cursor);
 }
 
+Point
+screencenter(void)
+{
+       Point sc;
+
+       sc = divpt(subpt(screen->r.max, screen->r.min), 2);
+       return addpt(screen->r.min, sc);
+}
+
 void
 dozoom(void)
 {
-       Point z, d;
-       double f, olds;
+       Point oxy, d, sc, off;
+       Vector gsc;
+       double z, oscale;
 
        setcursor(mc, &zoomcursor);
-
-       z = mc->xy;
-       olds = scale;
+       oxy = mc->xy;
+       oscale = scale;
+       sc = screencenter();
        for(;;) {
                readmouse(mc);
                if(mc->buttons != 2)
                        break;
-               d = subpt(mc->xy, z);
-               f = tanh((double)d.y/200) + 1;
+               d = subpt(mc->xy, oxy);
+               z = tanh((double)d.y/200) + 1;
+               gsc = tovector(sc);
                pause(0, 0);
-               scale = f*olds;
+               scale = z*oscale;
+               off = subpt(topoint(gsc), sc);
+               orig = subpt(orig, off);
                drawglxy();
                pause(1, 0);
        }
-
        setcursor(mc, cursor);
-       pause(1, 0);
 }
 
 void
@@ -579,6 +579,16 @@ Again:
        }
 }
 
+Vector
+tovector(Point p)
+{
+       Vector v;
+
+       v.x = (p.x-orig.x) * scale;
+       v.y = (p.y-orig.y) * scale;
+       return v;
+}
+
 void
 usage(void)
 {
@@ -632,8 +642,7 @@ threadmain(int argc, char **argv)
                sysfatal("initmouse failed: %r");
 
        dt² = dt*dt;
-       orig = divpt(subpt(screen->r.max, screen->r.min), 2);
-       orig = addpt(orig, screen->r.min);
+       orig = screencenter();
        glxyinit();
        quadsinit();
        if(doload)