1 files changed, 121 insertions, 0 deletions
diff --git a/include/fml/surface.h b/include/fml/surface.h
new file mode 100644
index 0000000..e42efe0
--- /dev/null
+++ b/include/fml/surface.h
@@ -0,0 +1,121 @@
+#ifndef SURFACE_H
+#define SURFACE_H
+
+#include "fml.h"
+#include "manifold.h"
+
+namespace fml {
+    /* All surfaces inherit this class */
+    /* The exact meaning of d is surface-dependent (see class
+     * definitions below); the limit of the calculated integral must
+     * approach its true value as d->0. d must be > 0. */
+    class Surface : public Manifold {
+    public:
+        const int dimension() const { return 2; }
+    };
+
+    class Plane : public Surface {
+    private:
+        /* The surface is specified by all points p = p0 + s v1 + t v2,
+         * such that 0 <= {s, t} < 1
+         *
+         * v1 and v2 must NOT be parallel.
+         *
+         * v1 and v2 should (but do not have to be) be normal (this is
+         * motivated primarily by usability; if the two vectors are indeed
+         * normal, then m1 and m2 have the nice geometric meaning of side
+         * length).
+         *
+         * d = ds = dt.
+         * dA will be in the direction of v1 x v2.
+         */
+        vec3 p0, v1, v2;
+
+    public:
+        Plane(vec3 p, vec3 _v1, vec3 _v2) : p0(p), v1(_v1), v2(_v2) {};
+
+        vec3 integrate(vec3 (*integrand)(vec3 s, vec3 dA), scalar d) const;
+        const char *name() const { return "Plane"; }
+    };
+
+/* Flat, circular disk (of varying extent) */
+    class Disk : public Surface {
+    private:
+        /* This represents a (possibly incomplete) circular disk in space,
+         * with a center, radius, and normal vector as specified.
+         *
+         * `angle' specifies the extent of the disk; angle=2pi for a full
+         * circle.
+         *
+         * We use:
+         * d = dr.
+         * d_theta = d / r.
+         *
+         * This makes it so that differential area elements on the edge of
+         * the disk are square.
+         *
+         * dA will be in the direction of normal.
+         */
+        vec3 center, radius, normal;
+        scalar angle;
+
+    public:
+        Disk(vec3 c, vec3 r, vec3 n, scalar a) : center(c), radius(r), normal(n), angle(a) {};
+
+        vec3 integrate(vec3 (*integrand)(vec3 s, vec3 dA), scalar d) const;
+        const char *name() const { return "Disk"; }
+    };
+
+/* Hollow, spherical shell */
+    class Sphere : public Surface {
+    private:
+        /* d = dtheta = dphi */
+
+        vec3 center;
+        scalar radius;
+
+    public:
+        Sphere(vec3 c, scalar r) : center(c), radius(r) {};
+
+        vec3 integrate(vec3 (*integrand)(vec3 s, vec3 dA), scalar d) const;
+        const char *name() const { return "Sphere"; }
+    };
+
+/* Cylinder without end caps */
+    class OpenCylinder : public Surface {
+    private:
+        /* Like this:
+         *
+         *         ___________________
+         *        / \                 \
+         *       origin ---------------> axis
+         *        \_/_________________/
+         *
+         */
+
+        vec3 origin, axis;
+        scalar radius;
+
+    public:
+        OpenCylinder(vec3 o, vec3 a, scalar r) : origin(o), axis(a), radius(r) {}
+
+        vec3 integrate(vec3 (*integrand)(vec3 s, vec3 dA), scalar d) const;
+        const char *name() const { return "OpenCylinder"; }
+    };
+
+/* Capped cylinder */
+    class ClosedCylinder : public OpenCylinder {
+    private:
+        Disk cap1, cap2;
+
+    public:
+        ClosedCylinder(vec3 o, vec3 a, scalar r) : OpenCylinder(o, a, r),
+                                                   cap1(o, vec3::any_unit_normal(a), -a.normalize(), 2*M_PI),
+                                                   cap2(o + a, vec3::any_unit_normal(a), a.normalize(), 2*M_PI) {}
+
+        vec3 integrate(vec3 (*integrand)(vec3 s, vec3 dA), scalar d) const;
+        const char *name() const { return "ClosedCylinder"; }
+    };
+}
+
+#endif