+#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);
+}