Danny Robson
f6056153e3
This places, at long last, the core library code into the same namespace as the extended library code.
71 lines
1.7 KiB
C++
71 lines
1.7 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2018 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_GEOM_FRUSTUM_HPP
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#define CRUFT_UTIL_GEOM_FRUSTUM_HPP
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#include "../matrix.hpp"
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#include "plane.hpp"
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#include "aabb.hpp"
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#include <array>
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#include <cstddef>
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namespace cruft::geom {
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/// a viewing frustrum comprised of 4 axis planes, a near plane, and a far
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/// plane. it may describe something other than a perspective projection
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/// (eg, an orthographic projection)
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template <typename ValueT>
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struct frustum {
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explicit frustum (const matrix<4,4,ValueT>&);
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std::array<plane<3,ValueT>, 6> planes;
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enum {
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X_NEG, X_POS,
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Y_NEG, Y_POS,
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Z_NEG, Z_POS,
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LEFT = X_NEG,
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RIGHT = X_POS,
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TOP = Y_POS,
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BOTTOM = Y_NEG,
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NEAR = Z_POS,
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FAR = Z_NEG
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};
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};
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using frustum3f = frustum<float>;
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/// tests whether a frustum and an aabb overlap
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///
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/// XXX: there may be occasional false positives.
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template <size_t S, typename T>
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bool
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intersects (const frustum<T> &f, const aabb<S,T> &b)
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{
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for (const auto &p: f.planes) {
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// find the distance to the point, if it's positive it's inside
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// the frustum.
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const auto d = max (
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p.coefficients * b.lo.template redim<S+1> (1),
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p.coefficients * b.hi.template redim<S+1> (1)
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);
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if (sum (d) < 0)
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return false;
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}
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return true;
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}
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};
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#endif
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