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+/**
+ @file Box.cpp
+ Box class
+
+ @maintainer Morgan McGuire, matrix@graphics3d.com
+
+ @created 2001-06-02
+ @edited 2006-02-05
+*/
+
+#include "G3D/Box.h"
+#include "G3D/debug.h"
+#include "G3D/Plane.h"
+#include "G3D/AABox.h"
+#include "G3D/CoordinateFrame.h"
+
+namespace G3D {
+
+/**
+ Sets a field on four vertices. Used by the constructor.
+ */
+#define setMany(i0, i1, i2, i3, field, extreme) \
+ _corner[i0].field = _corner[i1].field = \
+ _corner[i2].field = _corner[i3].field = \
+ (extreme).field
+
+Box::Box() {
+}
+
+
+Box::Box(const AABox& b) {
+ init(b.low(), b.high());
+}
+
+
+Box::Box(
+ const Vector3& min,
+ const Vector3& max) {
+
+ init(min.min(max), min.max(max));
+
+}
+
+void Box::init(
+ const Vector3& min,
+ const Vector3& max) {
+
+ setMany(0, 1, 2, 3, z, max);
+ setMany(4, 5, 6, 7, z, min);
+
+ setMany(1, 2, 5, 6, x, max);
+ setMany(0, 3, 4, 7, x, min);
+
+ setMany(3, 2, 6, 7, y, max);
+ setMany(0, 1, 5, 4, y, min);
+
+ _extent = max - min;
+
+ _axis[0] = Vector3::unitX();
+ _axis[1] = Vector3::unitY();
+ _axis[2] = Vector3::unitZ();
+
+ _volume = _extent.x * _extent.y * _extent.z;
+ _area = 2 *
+ (_extent.x * _extent.y +
+ _extent.y * _extent.z +
+ _extent.z * _extent.x);
+
+ _center = (max + min) / 2;
+}
+
+
+float Box::volume() const {
+ return _volume;
+}
+
+
+float Box::surfaceArea() const {
+ return _area;
+}
+
+
+void Box::getLocalFrame(CoordinateFrame& frame) const {
+
+ frame.rotation = Matrix3(
+ _axis[0][0], _axis[1][0], _axis[2][0],
+ _axis[0][1], _axis[1][1], _axis[2][1],
+ _axis[0][2], _axis[1][2], _axis[2][2]);
+
+ frame.translation = _center;
+}
+
+
+CoordinateFrame Box::localFrame() const {
+ CoordinateFrame out;
+ getLocalFrame(out);
+ return out;
+}
+
+
+void Box::getFaceCorners(int f, Vector3& v0, Vector3& v1, Vector3& v2, Vector3& v3) const {
+ switch (f) {
+ case 0:
+ v0 = _corner[0]; v1 = _corner[1]; v2 = _corner[2]; v3 = _corner[3];
+ break;
+
+ case 1:
+ v0 = _corner[1]; v1 = _corner[5]; v2 = _corner[6]; v3 = _corner[2];
+ break;
+
+ case 2:
+ v0 = _corner[7]; v1 = _corner[6]; v2 = _corner[5]; v3 = _corner[4];
+ break;
+
+ case 3:
+ v0 = _corner[2]; v1 = _corner[6]; v2 = _corner[7]; v3 = _corner[3];
+ break;
+
+ case 4:
+ v0 = _corner[3]; v1 = _corner[7]; v2 = _corner[4]; v3 = _corner[0];
+ break;
+
+ case 5:
+ v0 = _corner[1]; v1 = _corner[0]; v2 = _corner[4]; v3 = _corner[5];
+ break;
+
+ default:
+ debugAssert((f >= 0) && (f < 6));
+ }
+}
+
+
+bool Box::culledBy(
+ const Array<Plane>& plane,
+ int& cullingPlaneIndex,
+ const uint32 inMask,
+ uint32& outMask) const {
+
+ return culledBy(plane.getCArray(), plane.size(), cullingPlaneIndex, inMask, outMask);
+}
+
+
+bool Box::culledBy(
+ const Array<Plane>& plane,
+ int& cullingPlaneIndex,
+ const uint32 inMask) const {
+
+ return culledBy(plane.getCArray(), plane.size(), cullingPlaneIndex, inMask);
+}
+
+
+int32 Box::dummy = 0;
+
+bool Box::culledBy(
+ const class Plane* plane,
+ int numPlanes,
+ int& cullingPlane,
+ const uint32 _inMask,
+ uint32& childMask) const {
+
+ uint32 inMask = _inMask;
+ assert(numPlanes < 31);
+
+ childMask = 0;
+
+ // See if there is one plane for which all of the
+ // vertices are in the negative half space.
+ for (int p = 0; p < numPlanes; p++) {
+
+ // Only test planes that are not masked
+ if ((inMask & 1) != 0) {
+
+ Vector3 corner;
+
+ int numContained = 0;
+ int v = 0;
+
+ // We can early-out only if we have found one point on each
+ // side of the plane (i.e. if we are straddling). That
+ // occurs when (numContained < v) && (numContained > 0)
+ for (v = 0; (v < 8) && ((numContained == v) || (numContained == 0)); ++v) {
+ if (plane[p].halfSpaceContains(getCorner(v))) {
+ ++numContained;
+ }
+ }
+
+ if (numContained == 0) {
+ // Plane p culled the box
+ cullingPlane = p;
+
+ // The caller should not recurse into the children,
+ // since the parent is culled. If they do recurse,
+ // make them only test against this one plane, which
+ // will immediately cull the volume.
+ childMask = 1 << p;
+ return true;
+
+ } else if (numContained < v) {
+ // The bounding volume straddled the plane; we have
+ // to keep testing against this plane
+ childMask |= (1 << p);
+ }
+ }
+
+ // Move on to the next bit.
+ inMask = inMask >> 1;
+ }
+
+ // None of the planes could cull this box
+ cullingPlane = -1;
+ return false;
+}
+
+
+bool Box::culledBy(
+ const class Plane* plane,
+ int numPlanes,
+ int& cullingPlane,
+ const uint32 _inMask) const {
+
+ uint32 inMask = _inMask;
+ assert(numPlanes < 31);
+
+ // See if there is one plane for which all of the
+ // vertices are in the negative half space.
+ for (int p = 0; p < numPlanes; p++) {
+
+ // Only test planes that are not masked
+ if ((inMask & 1) != 0) {
+
+ bool culled = true;
+
+ int v;
+
+ // Assume this plane culls all points. See if there is a point
+ // not culled by the plane... early out when at least one point
+ // is in the positive half space.
+ for (v = 0; (v < 8) && culled; ++v) {
+ culled = ! plane[p].halfSpaceContains(getCorner(v));
+ }
+
+ if (culled) {
+ // Plane p culled the box
+ cullingPlane = p;
+
+ return true;
+ }
+ }
+
+ // Move on to the next bit.
+ inMask = inMask >> 1;
+ }
+
+ // None of the planes could cull this box
+ cullingPlane = -1;
+ return false;
+}
+
+
+bool Box::contains(
+ const Vector3& point) const {
+
+ // Form axes from three edges, transform the point into that
+ // space, and perform 3 interval tests
+
+ Vector3 u = _corner[4] - _corner[0];
+ Vector3 v = _corner[3] - _corner[0];
+ Vector3 w = _corner[1] - _corner[0];
+
+ Matrix3 M = Matrix3(u.x, v.x, w.x,
+ u.y, v.y, w.y,
+ u.z, v.z, w.z);
+
+ // M^-1 * (point - _corner[0]) = point in unit cube's object space
+ // compute the inverse of M
+ Vector3 osPoint = M.inverse() * (point - _corner[0]);
+
+ return
+ (osPoint.x >= 0) &&
+ (osPoint.y >= 0) &&
+ (osPoint.z >= 0) &&
+ (osPoint.x <= 1) &&
+ (osPoint.y <= 1) &&
+ (osPoint.z <= 1);
+}
+
+#undef setMany
+
+#if 0
+void Box::getRandomSurfacePoint(Vector3& P, Vector3& N) const {
+ float aXY = _extent.x * _extent.y;
+ float aYZ = _extent.y * _extent.z;
+ float aZX = _extent.z * _extent.x;
+
+ float r = (float)random(0, aXY + aYZ + aZX);
+
+ // Choose evenly between positive and negative face planes
+ float d = (random(0, 1) < 0.5f) ? -1.0f : 1.0f;
+
+ // The probability of choosing a given face is proportional to
+ // its area.
+ if (r < aXY) {
+ P = _axis[0] * (float)random(-0.5, 0.5) * _extent.x +
+ _axis[1] * (float)random(-0.5, 0.5) * _extent.y +
+ _center + _axis[2] * d * _extent.z * 0.5f;
+ N = _axis[2] * d;
+ } else if (r < aYZ) {
+ P = _axis[1] * (float)random(-0.5, 0.5) * _extent.y +
+ _axis[2] * (float)random(-0.5, 0.5) * _extent.z +
+ _center + _axis[0] * d * _extent.x * 0.5f;
+ N = _axis[0] * d;
+ } else {
+ P = _axis[2] * (float)random(-0.5, 0.5) * _extent.z +
+ _axis[0] *(float) random(-0.5, 0.5) * _extent.x +
+ _center + _axis[1] * d * _extent.y * 0.5f;
+ N = _axis[1] * d;
+ }
+}
+
+
+Vector3 Box::randomInteriorPoint() const {
+ Vector3 sum = _center;
+
+ for (int a = 0; a < 3; ++a) {
+ sum += _axis[a] * (float)random(-0.5, 0.5) * _extent[a];
+ }
+
+ return sum;
+}
+#endif
+
+
+void Box::getBounds(class AABox& aabb) const {
+
+ Vector3 lo = _corner[0];
+ Vector3 hi = lo;
+
+ for (int v = 1; v < 8; ++v) {
+ const Vector3& C = _corner[v];
+ lo = lo.min(C);
+ hi = hi.max(C);
+ }
+
+ aabb = AABox(lo, hi);
+}
+
+
+} // namespace