120 lines
3 KiB
C++
120 lines
3 KiB
C++
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// This code is in the public domain -- castanyo@yahoo.es
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#include "Box.h"
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#include "Box.inl"
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#include "Sphere.h"
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using namespace nv;
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// Clip the given segment against this box.
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bool Box::clipSegment(const Vector3 & origin, const Vector3 & dir, float * t_near, float * t_far) const {
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// Avoid aliasing.
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float tnear = *t_near;
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float tfar = *t_far;
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// clip ray segment to box
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for (int i = 0; i < 3; i++)
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{
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const float pos = origin.component[i] + tfar * dir.component[i];
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const float dt = tfar - tnear;
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if (dir.component[i] < 0) {
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// clip end point
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if (pos < minCorner.component[i]) {
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tfar = tnear + dt * (origin.component[i] - minCorner.component[i]) / (origin.component[i] - pos);
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}
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// clip start point
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if (origin.component[i] > maxCorner.component[i]) {
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tnear = tnear + dt * (origin.component[i] - maxCorner.component[i]) / (tfar * dir.component[i]);
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}
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}
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else {
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// clip end point
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if (pos > maxCorner.component[i]) {
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tfar = tnear + dt * (maxCorner.component[i] - origin.component[i]) / (pos - origin.component[i]);
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}
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// clip start point
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if (origin.component[i] < minCorner.component[i]) {
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tnear = tnear + dt * (minCorner.component[i] - origin.component[i]) / (tfar * dir.component[i]);
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}
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}
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if (tnear > tfar) {
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// Clipped away.
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return false;
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}
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}
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// Return result.
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*t_near = tnear;
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*t_far = tfar;
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return true;
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}
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float nv::distanceSquared(const Box &box, const Vector3 &point) {
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Vector3 closest;
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if (point.x < box.minCorner.x) closest.x = box.minCorner.x;
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else if (point.x > box.maxCorner.x) closest.x = box.maxCorner.x;
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else closest.x = point.x;
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if (point.y < box.minCorner.y) closest.y = box.minCorner.y;
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else if (point.y > box.maxCorner.y) closest.y = box.maxCorner.y;
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else closest.y = point.y;
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if (point.z < box.minCorner.z) closest.z = box.minCorner.z;
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else if (point.z > box.maxCorner.z) closest.z = box.maxCorner.z;
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else closest.z = point.z;
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return lengthSquared(point - closest);
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}
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bool nv::overlap(const Box &box, const Sphere &sphere) {
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return distanceSquared(box, sphere.center) < sphere.radius * sphere.radius;
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}
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bool nv::intersect(const Box & box, const Vector3 & p, const Vector3 & id, float * t /*= NULL*/) {
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// Precompute these in ray structure?
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int sdx = (id.x < 0);
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int sdy = (id.y < 0);
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int sdz = (id.z < 0);
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float tmin = (box.corner( sdx).x - p.x) * id.x;
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float tmax = (box.corner(1-sdx).x - p.x) * id.x;
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float tymin = (box.corner( sdy).y - p.y) * id.y;
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float tymax = (box.corner(1-sdy).y - p.y) * id.y;
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if ((tmin > tymax) || (tymin > tmax))
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return false;
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if (tymin > tmin) tmin = tymin;
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if (tymax < tmax) tmax = tymax;
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float tzmin = (box.corner( sdz).z - p.z) * id.z;
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float tzmax = (box.corner(1-sdz).z - p.z) * id.z;
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if ((tmin > tzmax) || (tzmin > tmax))
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return false;
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if (tzmin > tmin) tmin = tzmin;
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if (tzmax < tmax) tmax = tzmax;
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if (tmax < 0)
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return false;
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if (t != NULL) *t = tmin;
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return true;
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}
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