Lesson 0: Bresenham's Line Drawing Algorithm—First attempt

2 files changed, 246 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..0cd9e9a
--- /dev/null
+++ b/main.c
@@ -0,0 +1,222 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <thread.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <mouse.h>
+#include <keyboard.h>
+#include "libgeometry/geometry.h"
+
+
+Memimage *fb;
+Memimage *red;
+
+void resized(void);
+
+void*
+emalloc(ulong n)
+{
+	void *p;
+
+	p = malloc(n);
+	if(p == nil)
+		sysfatal("malloc: %r");
+	setmalloctag(p, getcallerpc(&n));
+	return p;
+}
+
+void*
+erealloc(void *p, ulong n)
+{
+	void *np;
+
+	np = realloc(p, n);
+	if(np == nil){
+		if(n == 0)
+			return nil;
+		sysfatal("realloc: %r");
+	}
+	if(p == nil)
+		setmalloctag(np, getcallerpc(&p));
+	else
+		setrealloctag(np, getcallerpc(&p));
+	return np;
+}
+
+Image*
+eallocimage(Display *d, Rectangle r, ulong chan, int repl, ulong col)
+{
+	Image *i;
+
+	i = allocimage(d, r, chan, repl, col);
+	if(i == nil)
+		sysfatal("allocimage: %r");
+	return i;
+}
+
+Memimage*
+eallocmemimage(Rectangle r, ulong chan)
+{
+	Memimage *i;
+
+	i = allocmemimage(r, chan);
+	if(i == nil)
+		sysfatal("allocmemimage: %r");
+	memfillcolor(i, DTransparent);
+	return i;
+}
+
+Memimage*
+rgb(ulong c)
+{
+	Memimage *i;
+
+	i = eallocmemimage(Rect(0,0,1,1), screen->chan);
+	i->flags |= Frepl;
+	i->clipr = Rect(-1e6, -1e6, 1e6, 1e6);
+	memfillcolor(i, c);
+	return i;
+}
+
+void
+pixel(Memimage *dst, Point p, Memimage *src)
+{
+	Rectangle r;
+
+	r.min = addpt(dst->r.min, p);
+	r.max = addpt(r.min, Pt(1,1));
+
+	memimagedraw(dst, r, src, ZP, nil, ZP, SoverD);
+}
+
+void
+bresenham(Memimage *dst, Point p0, Point p1, Memimage *src)
+{
+	double t, dt;
+	Point p;
+
+	dt = 0.01;
+
+	for(t = 0; t < 1; t += dt){
+		p = Pt(
+			flerp(p0.x, p1.x, t),
+			flerp(p0.y, p1.y, t)
+		);
+		pixel(dst, p, src);
+	}
+}
+
+void
+redraw(void)
+{
+	lockdisplay(display);
+	draw(screen, screen->r, display->black, nil, ZP);
+	loadimage(screen, screen->r, byteaddr(fb, fb->r.min), bytesperline(fb->r, fb->depth)*Dy(fb->r));
+	flushimage(display, 1);
+	unlockdisplay(display);
+}
+
+void
+rmb(Mousectl *, Keyboardctl *)
+{
+}
+
+void
+lmb(Mousectl *, Keyboardctl *)
+{
+}
+
+void
+mouse(Mousectl *mc, Keyboardctl *kc)
+{
+	if((mc->buttons&1) != 0)
+		lmb(mc, kc);
+	if((mc->buttons&4) != 0)
+		rmb(mc, kc);
+}
+
+void
+key(Rune r)
+{
+	switch(r){
+	case Kdel:
+	case 'q':
+		threadexitsall(nil);
+	}
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s\n", argv0);
+	exits("usage");
+}
+
+void
+threadmain(int argc, char *argv[])
+{
+	Mousectl *mc;
+	Keyboardctl *kc;
+	Rune r;
+
+	GEOMfmtinstall();
+	ARGBEGIN{
+	default: usage();
+	}ARGEND;
+	if(argc > 0)
+		usage();
+
+	if(newwindow(nil) < 0)
+		sysfatal("newwindow: %r");
+	if(initdraw(nil, nil, nil) < 0)
+		sysfatal("initdraw: %r");
+	if(memimageinit() != 0)
+		sysfatal("memimageinit: %r");
+	if((mc = initmouse(nil, screen)) == nil)
+		sysfatal("initmouse: %r");
+	if((kc = initkeyboard(nil)) == nil)
+		sysfatal("initkeyboard: %r");
+
+	fb = eallocmemimage(screen->r, screen->chan);
+	red = rgb(DRed);
+	bresenham(fb, Pt(40,40), Pt(300,300), red);
+
+	display->locking = 1;
+	unlockdisplay(display);
+	redraw();
+
+	for(;;){
+		enum { MOUSE, RESIZE, KEYBOARD };
+		Alt a[] = {
+			{mc->c, &mc->Mouse, CHANRCV},
+			{mc->resizec, nil, CHANRCV},
+			{kc->c, &r, CHANRCV},
+			{nil, nil, CHANEND}
+		};
+
+		switch(alt(a)){
+		case MOUSE:
+			mouse(mc, kc);
+			break;
+		case RESIZE:
+			resized();
+			break;
+		case KEYBOARD:
+			key(r);
+			break;
+		}
+
+		redraw();
+	}
+}
+
+void
+resized(void)
+{
+	lockdisplay(display);
+	if(getwindow(display, Refnone) < 0)
+		sysfatal("couldn't resize");
+	unlockdisplay(display);
+	redraw();
+}
diff --git a/mkfile b/mkfile
new file mode 100644
index 0000000..d6883d8
--- /dev/null
+++ b/mkfile
@@ -0,0 +1,24 @@
+</$objtype/mkfile
+
+BIN=/$objtype/bin/musw
+TARG=tinyrend
+OFILES=\
+	main.$O\
+
+HFILES=\
+	./libgeometry/geometry.h\
+
+LIB=\
+	./libgeometry/libgeometry.a$O\
+
+CFLAGS=$CFLAGS
+
+</sys/src/cmd/mkone
+
+./libgeometry/libgeometry.a$O:
+	cd ./libgeometry
+	mk install
+
+clean nuke:V:
+	rm -f *.[$OS] [$OS].??* $TARG
+	@{cd ./libgeometry; mk $target}