133 lines
4.6 KiB
C++
133 lines
4.6 KiB
C++
#pragma once
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#include "src/Core/Maths.h"
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#include <glm/matrix.hpp>
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#include <vector>
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namespace Nuake {
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class Frustum
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{
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public:
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Frustum() {}
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// m = ProjectionMatrix * ViewMatrix
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Frustum(Matrix4 m);
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// http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm
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bool IsBoxVisible(const Vector3& minp, const Vector3& maxp) const;
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private:
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enum Planes
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{
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Left = 0,
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Right,
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Bottom,
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Top,
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Near,
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Far,
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Count,
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Combinations = Count * (Count - 1) / 2
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};
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template<Planes i, Planes j>
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struct ij2k
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{
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enum { k = i * (9 - i) / 2 + j - 1 };
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};
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template<Planes a, Planes b, Planes c>
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Vector3 intersection(const Vector3* crosses) const;
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Vector4 m_planes[Count];
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Vector3 m_points[8];
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public:
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std::vector<Vector3> GetPoints()
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{
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std::vector<Vector3> result = std::vector<Vector3>();
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for (int i = 0; i < 8; i++)
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result.push_back(m_points[i]);
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return result;
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}
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};
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inline Frustum::Frustum(Matrix4 m)
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{
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m = glm::transpose(m);
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m_planes[Left] = m[3] + m[0];
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m_planes[Right] = m[3] - m[0];
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m_planes[Bottom] = m[3] + m[1];
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m_planes[Top] = m[3] - m[1];
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m_planes[Near] = m[3] + m[2];
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m_planes[Far] = m[3] - m[2];
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Vector3 crosses[Combinations] = {
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glm::cross(Vector3(m_planes[Left]), Vector3(m_planes[Right])),
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glm::cross(Vector3(m_planes[Left]), Vector3(m_planes[Bottom])),
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glm::cross(Vector3(m_planes[Left]), Vector3(m_planes[Top])),
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glm::cross(Vector3(m_planes[Left]), Vector3(m_planes[Near])),
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glm::cross(Vector3(m_planes[Left]), Vector3(m_planes[Far])),
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glm::cross(Vector3(m_planes[Right]), Vector3(m_planes[Bottom])),
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glm::cross(Vector3(m_planes[Right]), Vector3(m_planes[Top])),
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glm::cross(Vector3(m_planes[Right]), Vector3(m_planes[Near])),
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glm::cross(Vector3(m_planes[Right]), Vector3(m_planes[Far])),
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glm::cross(Vector3(m_planes[Bottom]), Vector3(m_planes[Top])),
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glm::cross(Vector3(m_planes[Bottom]), Vector3(m_planes[Near])),
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glm::cross(Vector3(m_planes[Bottom]), Vector3(m_planes[Far])),
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glm::cross(Vector3(m_planes[Top]), Vector3(m_planes[Near])),
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glm::cross(Vector3(m_planes[Top]), Vector3(m_planes[Far])),
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glm::cross(Vector3(m_planes[Near]), Vector3(m_planes[Far]))
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};
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m_points[0] = intersection<Left, Bottom, Near>(crosses);
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m_points[1] = intersection<Left, Top, Near>(crosses);
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m_points[2] = intersection<Right, Bottom, Near>(crosses);
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m_points[3] = intersection<Right, Top, Near>(crosses);
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m_points[4] = intersection<Left, Bottom, Far>(crosses);
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m_points[5] = intersection<Left, Top, Far>(crosses);
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m_points[6] = intersection<Right, Bottom, Far>(crosses);
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m_points[7] = intersection<Right, Top, Far>(crosses);
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}
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// http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm
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inline bool Frustum::IsBoxVisible(const Vector3& minp, const Vector3& maxp) const
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{
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// check box outside/inside of frustum
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for (int i = 0; i < Count; i++)
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{
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if ((glm::dot(m_planes[i], Vector4(minp.x, minp.y, minp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(maxp.x, minp.y, minp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(minp.x, maxp.y, minp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(maxp.x, maxp.y, minp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(minp.x, minp.y, maxp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(maxp.x, minp.y, maxp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(minp.x, maxp.y, maxp.z, 1.0f)) < 0.0) &&
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(glm::dot(m_planes[i], Vector4(maxp.x, maxp.y, maxp.z, 1.0f)) < 0.0))
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{
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return false;
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}
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}
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// check frustum outside/inside box
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int out;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].x > maxp.x) ? 1 : 0); if (out == 8) return false;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].x < minp.x) ? 1 : 0); if (out == 8) return false;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].y > maxp.y) ? 1 : 0); if (out == 8) return false;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].y < minp.y) ? 1 : 0); if (out == 8) return false;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].z > maxp.z) ? 1 : 0); if (out == 8) return false;
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out = 0; for (int i = 0; i < 8; i++) out += ((m_points[i].z < minp.z) ? 1 : 0); if (out == 8) return false;
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return true;
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}
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template<Frustum::Planes a, Frustum::Planes b, Frustum::Planes c>
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inline Vector3 Frustum::intersection(const Vector3* crosses) const
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{
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float D = glm::dot(Vector3(m_planes[a]), crosses[ij2k<b, c>::k]);
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Vector3 res = glm::mat3(crosses[ij2k<b, c>::k], -crosses[ij2k<a, c>::k], crosses[ij2k<a, b>::k]) *
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Vector3(m_planes[a].w, m_planes[b].w, m_planes[c].w);
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return res * (-1.0f / D);
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}
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}
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