More 3D auxiliary/convenience functions

[inkscape.git] / src / vanishing-point.h

diff --git a/src/vanishing-point.h b/src/vanishing-point.h
index cc11f9749e643a1be07e844ea2d01de3f801ee80..b7f3d12a1f8ec322d35f8e5481bdb36c11f0a54d 100644 (file)
--- a/src/vanishing-point.h
+++ b/src/vanishing-point.h
@@ -35,24 +35,72 @@ enum Axis {
     NONE = 0
 };
 
+// We use the fourth bit in binary representation
+// to indicate whether a face is front or rear.
+enum FrontOrRear { // find a better name
+    FRONT = 0,
+    REAR = 8
+};
+
+extern Axis axes[3];
+extern Axis planes[3];
+extern FrontOrRear face_positions [2];
+
+// Given a bit sequence that unambiguously specifies the face of a 3D box,
+// return a number between 0 and 5 corresponding to that particular face
+// (which is normally used to index an array). Return -1 if the bit sequence
+// does not specify a face. A face can either be given by its plane (e.g, XY)
+// or by the axis that is orthogonal to it (e.g., Z).
+inline gint face_to_int (guint face_id) {
+    switch (face_id) {
+      case 1:  return 0;
+      case 2:  return 2;
+      case 4:  return 4;
+      case 3:  return 4;
+      case 5:  return 2;
+      case 6:  return 0;
+
+      case 9:  return 1;
+      case 10: return 3;
+      case 12: return 5;
+      case 11: return 5;
+      case 13: return 3;
+      case 14: return 1;
+
+    default: return -1;
+    }
+}
 
 inline bool is_single_axis_direction (Box3D::Axis dir) {
     // tests whether dir is nonzero and a power of 2
     return (!(dir & (dir - 1)) && dir);
 }
 
-/** Given two axis directions out of {X, Y, Z}, returns the remaining one */
+/**
+ * Given two axis directions out of {X, Y, Z} or the corresponding plane, return the remaining one
+ * We don't check if 'plane' really specifies a plane (i.e., if it consists of precisely two directions).
+ */
 inline Box3D::Axis third_axis_direction (Box3D::Axis dir1, Box3D::Axis dir2) {
     return (Box3D::Axis) ((dir1 + dir2) ^ 0x7);
 }
+inline Box3D::Axis third_axis_direction (Box3D::Axis plane) {
+    return (Box3D::Axis) (plane ^ 0x7);
+}
 
-/* returns the first axis direction occuring in the (possibly compound) expression 'dirs' */
-inline Box3D::Axis extract_single_axis_direction (Box3D::Axis dirs) {
+/* returns the first/second axis direction occuring in the (possibly compound) expression 'dirs' */
+inline Box3D::Axis extract_first_axis_direction (Box3D::Axis dirs) {
     if (dirs & Box3D::X) return Box3D::X;
     if (dirs & Box3D::Y) return Box3D::Y;
     if (dirs & Box3D::Z) return Box3D::Z;
     return Box3D::NONE;
 }
+inline Box3D::Axis extract_second_axis_direction (Box3D::Axis dirs) {
+    return extract_first_axis_direction ((Box3D::Axis) (dirs ^ extract_first_axis_direction(dirs)));
+}
+
+inline Box3D::Axis orth_plane (Box3D::Axis axis) {
+    return (Box3D::Axis) (Box3D::XYZ ^ axis);
+}
 
 /* returns an axis direction perpendicular to the ones occuring in the (possibly compound) expression 'dirs' */
 inline Box3D::Axis get_perpendicular_axis_direction (Box3D::Axis dirs) {
@@ -62,6 +110,13 @@ inline Box3D::Axis get_perpendicular_axis_direction (Box3D::Axis dirs) {
     return Box3D::NONE;
 }
 
+inline gchar * string_from_axes (Box3D::Axis axes) {
+    GString *pstring = g_string_new("");
+    if (axes & Box3D::X) g_string_append_printf (pstring, "X");
+    if (axes & Box3D::Y) g_string_append_printf (pstring, "Y");
+    if (axes & Box3D::Z) g_string_append_printf (pstring, "Z");
+    return pstring->str;
+}
 
 // FIXME: Store the Axis of the VP inside the class
 class VanishingPoint : public NR::Point {