implemented fixed-time dynamics stepper, animated sprites and cleaned things up.

7 files changed, 249 insertions, 100 deletions

diff --git a/assets/sheets/NpcCemet.pic b/assets/sheets/NpcCemet.pic
new file mode 100644
index 0000000..7faaa29
--- /dev/null
+++ b/assets/sheets/NpcCemet.pic
diff --git a/dat.h b/dat.h
index 4dd4250..a3065ee 100644
--- a/dat.h
+++ b/dat.h
@@ -1,6 +1,7 @@
-typedef struct State State;
+typedef struct GameState GameState;
 typedef struct Derivative Derivative;
 typedef struct Stats Stats;
+typedef struct Sprite Sprite;
 
 struct Stats
 {
@@ -12,7 +13,7 @@ struct Stats
 	void (*update)(Stats*, double);
 };
 
-struct State
+struct GameState
 {
 	double x, v;
 	Stats stats;
@@ -22,3 +23,17 @@ struct Derivative
 {
 	double dx, dv;
 };
+
+struct Sprite
+{
+	Image *sheet;
+	Point sp;
+	Rectangle r;
+	int nframes;
+	int curframe;
+	ulong period;
+	ulong elapsed;
+
+	void (*step)(Sprite*, ulong);
+	void (*draw)(Sprite*, Image*, Point);
+};
diff --git a/fns.h b/fns.h
index 2325ae1..6898eec 100644
--- a/fns.h
+++ b/fns.h
@@ -9,3 +9,15 @@ Image *eallocimage(Display*, Rectangle, ulong, int, ulong);
  *	stats
  */
 void statsupdate(Stats*, double);
+
+/*
+ *	physics
+ */
+void integrate(GameState*, double, double);
+
+/*
+ *	sprite
+ */
+Sprite *newsprite(Image*, Point, Rectangle, int, ulong);
+Sprite *readsprite(char*, Point, Rectangle, int, ulong);
+void delsprite(Sprite*);
diff --git a/main.c b/main.c
index c7ae3a3..0610921 100644
--- a/main.c
+++ b/main.c
@@ -9,100 +9,11 @@
 #include "fns.h"
 
 RFrame screenrf;
-State state;
+GameState state;
 double t, Δt;
 
+Sprite *ghoul, *ghoulbig;
 
-/*
- *	Dynamics stepper
- *
- * 	Currently set to a basic spring-damper system.
- */
-double
-accel(State *s, double t)
-{
-	static double k = 15, b = 0.1;
-
-	USED(t);
-	return -k*s->x - b*s->v;
-}
-
-Derivative
-eval(State *s0, double t, double Δt, Derivative *d)
-{
-	State s;
-	Derivative res;
-
-	s.x = s0->x + d->dx*Δt;
-	s.v = s0->v + d->dv*Δt;
-
-	res.dx = s.v;
-	res.dv = accel(&s, t+Δt);
-	return res;
-}
-
-/*
- *	Explicit Euler Integrator
- */
-void
-euler0(State *s, double t, double Δt)
-{
-	static Derivative ZD = {0,0};
-	Derivative d;
-
-	d = eval(s, t, Δt, &ZD);
-
-	s->x += d.dx*Δt;
-	s->v += d.dv*Δt;
-}
-
-/*
- *	Semi-implicit Euler Integrator
- */
-void
-euler1(State *s, double t, double Δt)
-{
-	static Derivative ZD = {0,0};
-	Derivative d;
-
-	d = eval(s, t, Δt, &ZD);
-
-	s->v += d.dv*Δt;
-	s->x += s->v*Δt;
-}
-
-/*
- *	RK4 Integrator
- */
-void
-rk4(State *s, double t, double Δt)
-{
-	static Derivative ZD = {0,0};
-	Derivative a, b, c, d;
-	double dxdt, dvdt;
-
-	a = eval(s, t, 0, &ZD);
-	b = eval(s, t, Δt/2, &a);
-	c = eval(s, t, Δt/2, &b);
-	d = eval(s, t, Δt, &c);
-
-	dxdt = 1.0/6 * (a.dx + 2*(b.dx + c.dx) + d.dx);
-	dvdt = 1.0/6 * (a.dv + 2*(b.dv + c.dv) + d.dv);
-
-	s->x += dxdt*Δt;
-	s->v += dvdt*Δt;
-}
-
-/*
- *	The Integrator
- */
-void
-integrate(State *s, double t, double Δt)
-{
-	//euler0(s, t, Δt);
-	//euler1(s, t, Δt);
-	rk4(s, t, Δt);
-}
 
 Point
 toscreen(Point2 p)
@@ -117,6 +28,20 @@ fromscreen(Point p)
 	return rframexform(Pt2(p.x,p.y,1), screenrf);
 }
 
+//void
+//drawsimstats(void)
+//{
+//	char buf[128];
+//	int i;
+//
+//	for(i = 0; i < NSTATS; i++){
+//		snprint(buf, sizeof buf, "%.3f/%.3f/%.3f[%.3f]",
+//			simstats[i].min, simstats[i].avg, simstats[i].max,
+//			simstats[i].cur);
+//		string(screen, addpt(screen->r.min, Pt(10,30+i*font->height)), display->white, ZP, font, buf);
+//	}
+//}
+
 void
 drawtimestep(double t)
 {
@@ -153,6 +78,9 @@ redraw(void)
 	drawbar(state.stats.min); drawbar(state.stats.max); drawbar(state.stats.avg);
 	fillellipse(screen, toscreen(Pt2(0,state.x,1)), 2, 2, display->white, ZP);
 
+	ghoul->draw(ghoul, screen, toscreen(Pt2(100,-100,1)));
+	ghoulbig->draw(ghoulbig, screen, toscreen(Pt2(-100,-100,1)));
+
 	flushimage(display, 1);
 	unlockdisplay(display);
 }
@@ -171,7 +99,7 @@ resized(void)
 void
 resetsim(void)
 {
-	memset(&state, 0, sizeof(State));
+	memset(&state, 0, sizeof(GameState));
 	state.x = 100;
 	state.stats.update = statsupdate;
 	t = 0;
@@ -226,6 +154,8 @@ threadmain(int argc, char *argv[])
 	Mousectl *mc;
 	Keyboardctl *kc;
 	Rune r;
+	uvlong then, now;
+	double frametime, timeacc;
 
 	ARGBEGIN{
 	default: usage();
@@ -239,15 +169,22 @@ threadmain(int argc, char *argv[])
 		sysfatal("initmouse: %r");
 	if((kc = initkeyboard(nil)) == nil)
 		sysfatal("initkeyboard: %r");
+
+	display->locking = 1;
+	unlockdisplay(display);
+
 	screenrf.p = Pt2(screen->r.min.x+Dx(screen->r)/2,screen->r.max.y-Dy(screen->r)/2,1);
 	screenrf.bx = Vec2(1, 0);
 	screenrf.by = Vec2(0,-1);
 
+	ghoul = readsprite("assets/sheets/NpcCemet.pic", Pt(48,0), Rect(0,0,16,16), 5, 150);
+	ghoulbig = newsprite(ghoul->sheet, Pt(144,64), Rect(0,0,24,24), 5, 120);
+
 	Δt = 0.01;
+	then = nsec();
+	timeacc = 0;
 	resetsim();
 
-	display->locking = 1;
-	unlockdisplay(display);
 	redraw();
 
 	for(;;){
@@ -271,13 +208,24 @@ threadmain(int argc, char *argv[])
 			break;
 		}
 
-		integrate(&state, t, Δt);
+		now = nsec();
+		frametime = now - then;
+		then = now;
+		timeacc += frametime/1e9;
 
-		state.stats.update(&state.stats, state.x);
+		while(timeacc >= Δt){
+			integrate(&state, t, Δt);
 
-		redraw();
+			state.stats.update(&state.stats, state.x);
+
+			timeacc -= Δt;
+			t += Δt;
+		}
 
-		t += Δt;
+		ghoul->step(ghoul, frametime/1e6);
+		ghoulbig->step(ghoulbig, frametime/1e6);
+
+		redraw();
 
 		sleep(66);
 	}
diff --git a/mkfile b/mkfile
index 278bf28..2b07c93 100644
--- a/mkfile
+++ b/mkfile
@@ -5,6 +5,8 @@ TARG=physics
 OFILES=\
 	alloc.$O\
 	stats.$O\
+	physics.$O\
+	sprite.$O\
 	main.$O\
 
 HFILES=\
diff --git a/physics.c b/physics.c
new file mode 100644
index 0000000..5f45fd9
--- /dev/null
+++ b/physics.c
@@ -0,0 +1,100 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include "dat.h"
+#include "fns.h"
+
+//enum { DYNTIME, RENTIME, NSTATS };
+//Stats simstats[NSTATS];
+
+
+/*
+ *	Dynamics stepper
+ *
+ * 	Currently set to a basic spring-damper system.
+ */
+static double
+accel(GameState *s, double t)
+{
+	static double k = 15, b = 0.1;
+
+	USED(t);
+	return -k*s->x - b*s->v;
+}
+
+static Derivative
+eval(GameState *s0, double t, double Δt, Derivative *d)
+{
+	GameState s;
+	Derivative res;
+
+	s.x = s0->x + d->dx*Δt;
+	s.v = s0->v + d->dv*Δt;
+
+	res.dx = s.v;
+	res.dv = accel(&s, t+Δt);
+	return res;
+}
+
+/*
+ *	Explicit Euler Integrator
+ */
+static void
+euler0(GameState *s, double t, double Δt)
+{
+	static Derivative ZD = {0,0};
+	Derivative d;
+
+	d = eval(s, t, Δt, &ZD);
+
+	s->x += d.dx*Δt;
+	s->v += d.dv*Δt;
+}
+
+/*
+ *	Semi-implicit Euler Integrator
+ */
+static void
+euler1(GameState *s, double t, double Δt)
+{
+	static Derivative ZD = {0,0};
+	Derivative d;
+
+	d = eval(s, t, Δt, &ZD);
+
+	s->v += d.dv*Δt;
+	s->x += s->v*Δt;
+}
+
+/*
+ *	RK4 Integrator
+ */
+static void
+rk4(GameState *s, double t, double Δt)
+{
+	static Derivative ZD = {0,0};
+	Derivative a, b, c, d;
+	double dxdt, dvdt;
+
+	a = eval(s, t, 0, &ZD);
+	b = eval(s, t, Δt/2, &a);
+	c = eval(s, t, Δt/2, &b);
+	d = eval(s, t, Δt, &c);
+
+	dxdt = 1.0/6 * (a.dx + 2*(b.dx + c.dx) + d.dx);
+	dvdt = 1.0/6 * (a.dv + 2*(b.dv + c.dv) + d.dv);
+
+	s->x += dxdt*Δt;
+	s->v += dvdt*Δt;
+}
+
+/*
+ *	The Integrator
+ */
+void
+integrate(GameState *s, double t, double Δt)
+{
+	//euler0(s, t, Δt);
+	//euler1(s, t, Δt);
+	rk4(s, t, Δt);
+}
diff --git a/sprite.c b/sprite.c
new file mode 100644
index 0000000..a2bf290
--- /dev/null
+++ b/sprite.c
@@ -0,0 +1,72 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include "dat.h"
+#include "fns.h"
+
+static void
+sprite_step(Sprite *spr, ulong Δt)
+{
+	if(spr->nframes < 2)
+		return;
+
+	spr->elapsed += Δt;
+
+	if(spr->elapsed >= spr->period){
+		spr->elapsed -= spr->period;
+		spr->curframe = ++spr->curframe % spr->nframes;
+	}
+}
+
+static void
+sprite_draw(Sprite *spr, Image *dst, Point dp)
+{
+	Point sp = (Point){
+		spr->curframe * Dx(spr->r),
+		0
+	};
+	sp = addpt(spr->sp, sp);
+
+	draw(dst, rectaddpt(spr->r, dp), spr->sheet, nil, sp);
+}
+
+Sprite *
+newsprite(Image *sheet, Point sp, Rectangle r, int nframes, ulong period)
+{
+	Sprite *spr;
+
+	spr = emalloc(sizeof(Sprite));
+	spr->sheet = sheet;
+	spr->sp = sp;
+	spr->r = r;
+	spr->nframes = nframes;
+	spr->curframe = 0;
+	spr->period = period;
+	spr->elapsed = 0;
+	spr->step = sprite_step;
+	spr->draw = sprite_draw;
+
+	return spr;
+}
+
+Sprite *
+readsprite(char *sheetfile, Point sp, Rectangle r, int nframes, ulong period)
+{
+	Image *sheet;
+	int fd;
+
+	fd = open(sheetfile, OREAD);
+	if(fd < 0)
+		sysfatal("readsprite: %r");
+	sheet = readimage(display, fd, 1);
+	close(fd);
+
+	return newsprite(sheet, sp, r, nframes, period);
+}
+
+void
+delsprite(Sprite *spr)
+{
+	freeimage(spr->sheet);
+	free(spr);
+}