1 files changed, 84 insertions, 0 deletions
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);
+}