💿🐜 Antkeeper source code
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317 lines
7.5 KiB
317 lines
7.5 KiB
/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_GEOM_PRIMITIVES_VIEW_FRUSTUM_HPP
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#define ANTKEEPER_GEOM_PRIMITIVES_VIEW_FRUSTUM_HPP
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#include <engine/math/vector.hpp>
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#include <engine/math/matrix.hpp>
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#include <engine/geom/primitives/plane.hpp>
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#include <engine/geom/primitives/box.hpp>
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#include <engine/geom/primitives/sphere.hpp>
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namespace geom {
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namespace primitives {
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/**
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* View frustum.
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*
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* @tparam T Real type.
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*/
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template <class T>
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struct view_frustum
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{
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/// Vector type.
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using vector_type = math::vector<T, 3>;
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/// Plane type.
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using plane_type = geom::plane<T>;
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/// View-projection matrix type.
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using matrix_type = math::matrix<T, 4, 4>;
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/// Box type.
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using box_type = geom::box<T>;
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/// Sphere type.
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using sphere_type = geom::sphere<T>;
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/// Constructs a view frustum
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constexpr view_frustum() noexcept = default;
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/**
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* Constructs a view frustum by extracting planes from view-projection matrix.
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*
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* @param matrix View-projection matrix from which to extract view frustum planes.
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*/
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inline explicit constexpr view_frustum(const matrix_type& matrix) noexcept
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{
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extract(matrix);
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}
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/// Returns the left clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& left() const noexcept
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{
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return planes[0];
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}
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[[nodiscard]] inline constexpr plane_type& left() noexcept
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{
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return planes[0];
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}
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/// @}
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/// Returns the right clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& right() const noexcept
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{
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return planes[1];
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}
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[[nodiscard]] inline constexpr plane_type& right() noexcept
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{
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return planes[1];
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}
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/// @}
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/// Returns the bottom clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& bottom() const noexcept
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{
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return planes[2];
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}
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[[nodiscard]] inline constexpr plane_type& bottom() noexcept
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{
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return planes[2];
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}
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/// @}
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/// Returns the top clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& top() const noexcept
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{
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return planes[3];
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}
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[[nodiscard]] inline constexpr plane_type& top() noexcept
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{
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return planes[3];
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}
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/// @}
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/// Returns the near clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& near() const noexcept
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{
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return planes[4];
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}
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[[nodiscard]] inline constexpr plane_type& near() noexcept
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{
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return planes[4];
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}
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/// @}
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/// Returns the far clipping plane.
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/// @{
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[[nodiscard]] inline constexpr const plane_type& far() const noexcept
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{
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return planes[5];
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}
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[[nodiscard]] inline constexpr plane_type& far() noexcept
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{
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return planes[5];
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}
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/// @}
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/**
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* Extracts the view frustum planes from a view-projection matrix.
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*
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* @param matrix View-projection matrix from which to extract view frustum planes.
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*/
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void extract(const matrix_type& matrix) noexcept
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{
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for (std::size_t i = 0; i < 6; ++i)
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{
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plane_type& plane = planes[i];
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const std::size_t j = i >> 1;
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// Extract plane coefficients
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if (i % 2)
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{
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plane.normal.x() = matrix[0][3] - matrix[0][j];
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plane.normal.y() = matrix[1][3] - matrix[1][j];
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plane.normal.z() = matrix[2][3] - matrix[2][j];
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plane.constant = matrix[3][3] - matrix[3][j];
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}
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else
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{
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plane.normal.x() = matrix[0][3] + matrix[0][j];
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plane.normal.y() = matrix[1][3] + matrix[1][j];
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plane.normal.z() = matrix[2][3] + matrix[2][j];
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plane.constant = matrix[3][3] + matrix[3][j];
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}
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// Normalize plane coefficients
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const T inv_length = math::inv_length(plane.normal);
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plane.normal *= inv_length;
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plane.constant *= inv_length;
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}
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}
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/**
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* Tests for intersection between an axis-aligned box and the view frustum.
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*
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* @param box Box to test for intersection with the view frustum.
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*
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* @return `true` if the axis-aligned box intersects the view frustum, `false` otherwise.
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*/
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[[nodiscard]] bool intersects(const box_type& box) const noexcept
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{
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for (const auto& plane: planes)
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{
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const vector_type p
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{
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(plane.normal.x() > T{0}) ? box.max.x() : box.min.x(),
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(plane.normal.y() > T{0}) ? box.max.y() : box.min.y(),
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(plane.normal.z() > T{0}) ? box.max.z() : box.min.z()
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};
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if (plane.distance(p) < T{0})
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Tests for intersection between a sphere and the view frustum.
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*
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* @param sphere Sphere to test for intersection with the view frustum.
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*
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* @return `true` if the sphere intersects the view frustum, `false` otherwise.
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*/
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[[nodiscard]] bool intersects(const sphere_type& sphere) const noexcept
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{
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for (const auto& plane: planes)
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{
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if (plane.distance(sphere.center) < -sphere.radius)
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Tests whether a point is contained within this view frustum.
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*
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* @param point Point to test for containment.
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*
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* @return `true` if the point is contained within this view frustum, `false` otherwise.
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*/
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[[nodiscard]] constexpr bool contains(const vector_type& point) const noexcept
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{
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for (const auto& plane: planes)
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{
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if (plane.distance(point) < T{0})
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Checks if an axis-aligned box is completely contained within the view frustum.
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*
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* @param box Box to test for containment within the view frustum.
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*
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* @return `true` if the axis-aligned box is completely contained within the view frustum, `false` otherwise.
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*/
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[[nodiscard]] bool contains(const box_type& box) const noexcept
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{
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for (const auto& plane: planes)
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{
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const vector_type p
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{
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(plane.normal.x() > T{0}) ? box.max.x() : box.min.x(),
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(plane.normal.y() > T{0}) ? box.max.y() : box.min.y(),
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(plane.normal.z() > T{0}) ? box.max.z() : box.min.z()
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};
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const vector_type n
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{
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(plane.normal.x() < T{0}) ? box.max.x() : box.min.x(),
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(plane.normal.y() < T{0}) ? box.max.y() : box.min.y(),
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(plane.normal.z() < T{0}) ? box.max.z() : box.min.z()
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};
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if (plane.distance(p) < T{0} || plane.distance(n) < T{0})
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{
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return false;
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}
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}
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return true;
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}
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/**
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* Checks if a sphere is completely contained within the view frustum.
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*
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* @param sphere Sphere to test for containment within the view frustum.
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*
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* @return `true` if the sphere is completely contained within the view frustum, `false` otherwise.
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*/
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[[nodiscard]] bool contains(const sphere_type& sphere) const noexcept
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{
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for (const auto& plane: planes)
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{
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if (plane.distance(sphere.center) < sphere.radius)
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{
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return false;
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}
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}
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return true;
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}
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/**
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* View frustum clipping planes.
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*
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* Clipping planes are stored in the following order:
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*
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* 1. left
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* 2. right
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* 3. bottom
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* 4. top
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* 5. near
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* 6. far
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*/
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plane_type planes[6];
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};
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} // namespace primitives
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using namespace primitives;
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} // namespace geom
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#endif // ANTKEEPER_GEOM_PRIMITIVES_VIEW_FRUSTUM_HPP
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