after a year or so of work, i dare create a proper repo.

8 files changed, 873 insertions, 0 deletions

diff --git a/libgraphics/camera.c b/libgraphics/camera.c
new file mode 100644
index 0000000..c850477
--- /dev/null
+++ b/libgraphics/camera.c
@@ -0,0 +1,103 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include "../geometry.h"
+#include "../graphics.h"
+
+static int
+max(int a, int b)
+{
+	return a > b ? a : b;
+}
+
+static void
+verifycfg(Camera *c)
+{
+	assert(c->viewport != nil);
+	if(c->ptype == Ppersp)
+		assert(c->fov >= 1 && c->fov < 360);
+	assert(c->clip.n > 0 && c->clip.n < c->clip.f);
+}
+
+void
+perspective(Matrix3 m, double fov, double a, double n, double f)
+{
+	double cotan;
+
+	cotan = 1/tan(fov/2*DEG);
+	identity3(m);
+	m[0][0] =  cotan/a;
+	m[1][1] =  cotan;
+	m[2][2] = -(f+n)/(f-n);
+	m[2][3] = -2*f*n/(f-n);
+	m[3][2] = -1;
+}
+
+void
+orthographic(Matrix3 m, double l, double r, double b, double t, double n, double f)
+{
+	identity3(m);
+	m[0][0] =  2/(r - l);
+	m[1][1] =  2/(t - b);
+	m[2][2] = -2/(f - n);
+	m[0][3] = -(r + l)/(r - l);
+	m[1][3] = -(t + b)/(t - b);
+	m[2][3] = -(f + n)/(f - n);
+}
+
+void
+configcamera(Camera *c, Image *v, double fov, double n, double f, Projection p)
+{
+	c->viewport = v;
+	c->fov = fov;
+	c->clip.n = n;
+	c->clip.f = f;
+	c->ptype = p;
+	reloadcamera(c);
+}
+
+void
+placecamera(Camera *c, Point3 p, Point3 focus, Point3 up)
+{
+	c->p = p;
+	if(focus.w == 0)
+		c->bz = focus;
+	else
+		c->bz = normvec3(subpt3(c->p, focus));
+	c->bx = normvec3(crossvec3(up, c->bz));
+	c->by = crossvec3(c->bz, c->bx);
+}
+
+void
+aimcamera(Camera *c, Point3 focus)
+{
+	placecamera(c, c->p, focus, c->by);
+}
+
+void
+reloadcamera(Camera *c)
+{
+	double a;
+	double l, r, b, t;
+
+	verifycfg(c);
+	switch(c->ptype){
+	case Portho:
+		/*
+		r = Dx(c->viewport->r)/2;
+		t = Dy(c->viewport->r)/2;
+		l = -r;
+		b = -t;
+		*/
+		l = t = 0;
+		r = Dx(c->viewport->r);
+		b = Dy(c->viewport->r);
+		orthographic(c->proj, l, r, b, t, c->clip.n, c->clip.f);
+		break;
+	case Ppersp:
+		a = (double)Dx(c->viewport->r)/Dy(c->viewport->r);
+		perspective(c->proj, c->fov, a, c->clip.n, c->clip.f);
+		break;
+	default: sysfatal("unknown projection type");
+	}
+}
diff --git a/libgraphics/doc/libgraphics.ms b/libgraphics/doc/libgraphics.ms
new file mode 100644
index 0000000..87a23a7
--- /dev/null
+++ b/libgraphics/doc/libgraphics.ms
@@ -0,0 +1,34 @@
+.TL
+libgraphics
+.AU
+Rodrigo G. López
+.sp
+rgl@antares-labs.eu
+.AI
+Antares Telecom Laboratories
+Albatera, Alicante
+.FS
+ACHTUNG! this is a
+.B "WORK IN PROGRESS"
+.FE
+.NH 1
+Data Structures
+.NH 2
+Camera
+.P1
+struct Camera {
+	RFrame3;		/* VCS */
+	Image *viewport;
+	double fov;		/* vertical FOV */
+	struct {
+		double n, f;	/* near and far clipping planes */
+	} clip;
+	Projection ptype;
+	Matrix3 proj;		/* VCS to viewport xform */
+};
+.P2
+.PP
+A camera is an image capturing entity, analog to the real world device
+we all know, that allows us to see the virtual 3-D world by projecting
+it into a viewport we can attach to a screen or window for real-time
+visualization or write out into a file.
diff --git a/libgraphics/doc/libgraphics.pdf b/libgraphics/doc/libgraphics.pdf
new file mode 100644
index 0000000..0291710
--- /dev/null
+++ b/libgraphics/doc/libgraphics.pdf
diff --git a/libgraphics/doc/libgraphics.ps b/libgraphics/doc/libgraphics.ps
new file mode 100644
index 0000000..1a566f7
--- /dev/null
+++ b/libgraphics/doc/libgraphics.ps
@@ -0,0 +1,583 @@
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+%
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+		/@RealFindfont systemdict begin /findfont load end def
+	end
+} if
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+	dup NewFontDirectory exch known not {
+		dup
+		%dup systemdict /findfont get exec	% not always in systemdict
+		dup userdict /@RealFindfont get exec
+		dup /Encoding get StandardEncoding eq {
+			dup length dict begin
+				{1 index /FID ne {def}{pop pop} ifelse} forall
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+				currentdict
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diff --git a/libgraphics/doc/mkfile b/libgraphics/doc/mkfile
new file mode 100644
index 0000000..3bac031
--- /dev/null
+++ b/libgraphics/doc/mkfile
@@ -0,0 +1,15 @@
+FONTS='.FP lucidasans'
+DOCNAME=libgraphics
+
+all:VQ: $DOCNAME.ps $DOCNAME.pdf
+
+clean:VQ:
+	rm -f $DOCNAME.ps $DOCNAME.pdf
+
+$DOCNAME.ps:V: $DOCNAME.ms
+	{echo $FONTS; cat $prereq}> _$prereq
+	eval `{doctype _$prereq} | lp -dstdout > $target && rm -f _$prereq
+
+$DOCNAME.pdf:V: $DOCNAME.ps
+	cat /sys/doc/docfonts $prereq > _$prereq
+	ps2pdf _$prereq $target && rm -f _$prereq
diff --git a/libgraphics/mkfile b/libgraphics/mkfile
new file mode 100644
index 0000000..b7669a3
--- /dev/null
+++ b/libgraphics/mkfile
@@ -0,0 +1,11 @@
+</$objtype/mkfile
+
+LIB=../libgraphics.a$O
+OFILES=\
+	triangle.$O\
+	camera.$O\
+	render.$O\
+
+HFILES=../graphics.h
+
+</sys/src/cmd/mklib
diff --git a/libgraphics/render.c b/libgraphics/render.c
new file mode 100644
index 0000000..f4e4c0f
--- /dev/null
+++ b/libgraphics/render.c
@@ -0,0 +1,84 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include "../geometry.h"
+#include "../graphics.h"
+
+/*
+ * careful with concurrent rendering.
+ * use a lock or embed on each routine.
+ */
+static RFrame imgrframe = {
+	0,  0, 1,	/* p */
+	1,  0, 0,	/* bx */
+	0, -1, 0	/* by */
+};
+
+/* requires p to be in NDC */
+int
+isclipping(Point3 p)
+{
+	if(p.x > p.w || p.x < -p.w ||
+	   p.y > p.w || p.y < -p.w ||
+	   p.z > p.w || p.z < 0)
+		return 1;
+	return 0;
+}
+
+static Point2
+flatten(Camera *c, Point3 p)
+{
+	Point2 p2;
+	Matrix S = {
+		Dx(c->viewport->r)/2, 0, 0,
+		0, Dy(c->viewport->r)/2, 0,
+		0, 0, 1,
+	}, T = {
+		1, 0, 1,
+		0, 1, 1,
+		0, 0, 1,
+	};
+
+	p2 = (Point2){p.x, p.y, p.w};
+	if(p2.w != 0)
+		p2 = divpt2(p2, p2.w);
+	mulm(S, T);
+	p2 = xform(p2, S);
+	return p2;
+}
+
+Point
+toviewport(Camera *c, Point3 p)
+{
+	Point2 p2;
+
+	imgrframe.p = Pt2(c->viewport->r.min.x, c->viewport->r.max.y, 1);
+	p2 = invrframexform(flatten(c, p), imgrframe);
+	return (Point){p2.x, p2.y};
+}
+
+Point2
+fromviewport(Camera *c, Point p)
+{
+	imgrframe.p = Pt2(c->viewport->r.min.x, c->viewport->r.max.y, 1);
+	return rframexform(Pt2(p.x, p.y, 1), imgrframe);
+}
+
+void
+line3(Camera *c, Point3 p0, Point3 p1, int end0, int end1, Image *src)
+{
+	p0 = WORLD2NDC(c, p0);
+	p1 = WORLD2NDC(c, p1);
+	if(isclipping(p0) || isclipping(p1))
+		return;
+	line(c->viewport, toviewport(c, p0), toviewport(c, p1), end0, end1, 0, src, ZP);
+}
+
+Point
+string3(Camera *c, Point3 p, Image *src, Font *f, char *s)
+{
+	p = WORLD2NDC(c, p);
+	if(isclipping(p))
+		return (Point){~0, ~0};
+	return string(c->viewport, toviewport(c, p), src, ZP, f, s);
+}
diff --git a/libgraphics/triangle.c b/libgraphics/triangle.c
new file mode 100644
index 0000000..b598855
--- /dev/null
+++ b/libgraphics/triangle.c
@@ -0,0 +1,43 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include "../geometry.h"
+#include "../graphics.h"
+
+Triangle
+Trian(int x0, int y0, int x1, int y1, int x2, int y2)
+{
+	return (Triangle){Pt(x0, y0), Pt(x1, y1), Pt(x2, y2)};
+}
+
+Triangle
+Trianpt(Point p0, Point p1, Point p2)
+{
+	return (Triangle){p0, p1, p2};
+}
+
+void
+triangle(Image *dst, Triangle t, int thick, Image *src, Point sp)
+{
+	Point pl[4];
+
+	pl[0] = t.p0;
+	pl[1] = t.p1;
+	pl[2] = t.p2;
+	pl[3] = pl[0];
+
+	poly(dst, pl, nelem(pl), 0, 0, thick, src, sp);
+}
+
+void
+filltriangle(Image *dst, Triangle t, Image *src, Point sp)
+{
+	Point pl[4];
+
+	pl[0] = t.p0;
+	pl[1] = t.p1;
+	pl[2] = t.p2;
+	pl[3] = pl[0];
+
+	fillpoly(dst, pl, nelem(pl), 0, src, sp);
+}