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@podgorskiy
Created July 12, 2017 10:33
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Ready to use frustum culling code. Depends only on GLM. The input is only bounding box and ProjectionView matrix. Based on Inigo Quilez's code.
#include <glm/matrix.hpp>
class Frustum
{
public:
Frustum() {}
// m = ProjectionMatrix * ViewMatrix
Frustum(glm::mat4 m);
// http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm
bool IsBoxVisible(const glm::vec3& minp, const glm::vec3& maxp) const;
private:
enum Planes
{
Left = 0,
Right,
Bottom,
Top,
Near,
Far,
Count,
Combinations = Count * (Count - 1) / 2
};
template<Planes i, Planes j>
struct ij2k
{
enum { k = i * (9 - i) / 2 + j - 1 };
};
template<Planes a, Planes b, Planes c>
glm::vec3 intersection(const glm::vec3* crosses) const;
glm::vec4 m_planes[Count];
glm::vec3 m_points[8];
};
inline Frustum::Frustum(glm::mat4 m)
{
m = glm::transpose(m);
m_planes[Left] = m[3] + m[0];
m_planes[Right] = m[3] - m[0];
m_planes[Bottom] = m[3] + m[1];
m_planes[Top] = m[3] - m[1];
m_planes[Near] = m[3] + m[2];
m_planes[Far] = m[3] - m[2];
glm::vec3 crosses[Combinations] = {
glm::cross(glm::vec3(m_planes[Left]), glm::vec3(m_planes[Right])),
glm::cross(glm::vec3(m_planes[Left]), glm::vec3(m_planes[Bottom])),
glm::cross(glm::vec3(m_planes[Left]), glm::vec3(m_planes[Top])),
glm::cross(glm::vec3(m_planes[Left]), glm::vec3(m_planes[Near])),
glm::cross(glm::vec3(m_planes[Left]), glm::vec3(m_planes[Far])),
glm::cross(glm::vec3(m_planes[Right]), glm::vec3(m_planes[Bottom])),
glm::cross(glm::vec3(m_planes[Right]), glm::vec3(m_planes[Top])),
glm::cross(glm::vec3(m_planes[Right]), glm::vec3(m_planes[Near])),
glm::cross(glm::vec3(m_planes[Right]), glm::vec3(m_planes[Far])),
glm::cross(glm::vec3(m_planes[Bottom]), glm::vec3(m_planes[Top])),
glm::cross(glm::vec3(m_planes[Bottom]), glm::vec3(m_planes[Near])),
glm::cross(glm::vec3(m_planes[Bottom]), glm::vec3(m_planes[Far])),
glm::cross(glm::vec3(m_planes[Top]), glm::vec3(m_planes[Near])),
glm::cross(glm::vec3(m_planes[Top]), glm::vec3(m_planes[Far])),
glm::cross(glm::vec3(m_planes[Near]), glm::vec3(m_planes[Far]))
};
m_points[0] = intersection<Left, Bottom, Near>(crosses);
m_points[1] = intersection<Left, Top, Near>(crosses);
m_points[2] = intersection<Right, Bottom, Near>(crosses);
m_points[3] = intersection<Right, Top, Near>(crosses);
m_points[4] = intersection<Left, Bottom, Far>(crosses);
m_points[5] = intersection<Left, Top, Far>(crosses);
m_points[6] = intersection<Right, Bottom, Far>(crosses);
m_points[7] = intersection<Right, Top, Far>(crosses);
}
// http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm
inline bool Frustum::IsBoxVisible(const glm::vec3& minp, const glm::vec3& maxp) const
{
// check box outside/inside of frustum
for (int i = 0; i < Count; i++)
{
if ((glm::dot(m_planes[i], glm::vec4(minp.x, minp.y, minp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(maxp.x, minp.y, minp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(minp.x, maxp.y, minp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(maxp.x, maxp.y, minp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(minp.x, minp.y, maxp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(maxp.x, minp.y, maxp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(minp.x, maxp.y, maxp.z, 1.0f)) < 0.0) &&
(glm::dot(m_planes[i], glm::vec4(maxp.x, maxp.y, maxp.z, 1.0f)) < 0.0))
{
return false;
}
}
// check frustum outside/inside box
int out;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].x > maxp.x) ? 1 : 0); if (out == 8) return false;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].x < minp.x) ? 1 : 0); if (out == 8) return false;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].y > maxp.y) ? 1 : 0); if (out == 8) return false;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].y < minp.y) ? 1 : 0); if (out == 8) return false;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].z > maxp.z) ? 1 : 0); if (out == 8) return false;
out = 0; for (int i = 0; i<8; i++) out += ((m_points[i].z < minp.z) ? 1 : 0); if (out == 8) return false;
return true;
}
template<Frustum::Planes a, Frustum::Planes b, Frustum::Planes c>
inline glm::vec3 Frustum::intersection(const glm::vec3* crosses) const
{
float D = glm::dot(glm::vec3(m_planes[a]), crosses[ij2k<b, c>::k]);
glm::vec3 res = glm::mat3(crosses[ij2k<b, c>::k], -crosses[ij2k<a, c>::k], crosses[ij2k<a, b>::k]) *
glm::vec3(m_planes[a].w, m_planes[b].w, m_planes[c].w);
return res * (-1.0f / D);
}
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ghost commented Aug 2, 2020

This works nicely, thanks a lot!

@fqhd
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fqhd commented Jan 4, 2021

God bless your soul mate

@GIORGI095
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thanks, but whats &maxp, & minp

@Efore
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Efore commented Mar 27, 2021

thanks, but whats &maxp, & minp

Thats the max point and min point of the AABB of the object that is being checked

@Bixilon
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Bixilon commented Jun 2, 2021

Under what license is the code?

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ghost commented Jun 22, 2021

Thanks, very useful.

@Mormert
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Mormert commented Feb 21, 2022

I used this in my Minecraft clone game to test how it would improve performance. ~3x FPS. Works perfectly, thanks!!

@griffi-gh
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griffi-gh commented Jan 27, 2023

you should probably use constexprs instead of enum templates

@griffi-gh
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