2 files changed, 135 insertions, 0 deletions

diff --git a/src/graphics/Frustrum.cpp b/src/graphics/Frustrum.cpp
new file mode 100644
index 0000000..75f47c5
--- /dev/null
+++ b/src/graphics/Frustrum.cpp
@@ -0,0 +1,111 @@
+#include "Frustrum.hpp"
+
+enum FrustumSide {
+	RIGHT = 0,        // The RIGHT side of the frustum
+	LEFT = 1,        // The LEFT	 side of the frustum
+	BOTTOM = 2,        // The BOTTOM side of the frustum
+	TOP = 3,        // The TOP side of the frustum
+	BACK = 4,        // The BACK	side of the frustum
+	FRONT = 5            // The FRONT side of the frustum
+};
+
+enum PlaneData {
+	A = 0,                // The X value of the plane's normal
+	B = 1,                // The Y value of the plane's normal
+	C = 2,                // The Z value of the plane's normal
+	D = 3                // The distance the plane is from the origin
+};
+
+void normalizePlane(glm::vec4 &frustum_plane) {
+	float magnitude = (float) sqrt(frustum_plane[A] * frustum_plane[A] + frustum_plane[B] * frustum_plane[B] +
+	                               frustum_plane[C] * frustum_plane[C]);
+	frustum_plane[A] /= magnitude;
+	frustum_plane[B] /= magnitude;
+	frustum_plane[C] /= magnitude;
+	frustum_plane[D] /= magnitude;
+}
+
+void Frustum::CalculateFrustum(glm::mat4 &view_matrix, glm::mat4 &proj_matrix) {
+	float proj[16];
+	float modl[16];
+	const float *projP = glm::value_ptr(proj_matrix);
+	const float *modlP = glm::value_ptr(view_matrix);
+	for (int i = 0; i < 16; i++) {
+		proj[i]=projP[i];
+		modl[i]=modlP[i];
+	}
+
+	float clip[16]; //clipping planes
+
+	clip[0] = modl[0] * proj[0] + modl[1] * proj[4] + modl[2] * proj[8] + modl[3] * proj[12];
+	clip[1] = modl[0] * proj[1] + modl[1] * proj[5] + modl[2] * proj[9] + modl[3] * proj[13];
+	clip[2] = modl[0] * proj[2] + modl[1] * proj[6] + modl[2] * proj[10] + modl[3] * proj[14];
+	clip[3] = modl[0] * proj[3] + modl[1] * proj[7] + modl[2] * proj[11] + modl[3] * proj[15];
+
+	clip[4] = modl[4] * proj[0] + modl[5] * proj[4] + modl[6] * proj[8] + modl[7] * proj[12];
+	clip[5] = modl[4] * proj[1] + modl[5] * proj[5] + modl[6] * proj[9] + modl[7] * proj[13];
+	clip[6] = modl[4] * proj[2] + modl[5] * proj[6] + modl[6] * proj[10] + modl[7] * proj[14];
+	clip[7] = modl[4] * proj[3] + modl[5] * proj[7] + modl[6] * proj[11] + modl[7] * proj[15];
+
+	clip[8] = modl[8] * proj[0] + modl[9] * proj[4] + modl[10] * proj[8] + modl[11] * proj[12];
+	clip[9] = modl[8] * proj[1] + modl[9] * proj[5] + modl[10] * proj[9] + modl[11] * proj[13];
+	clip[10] = modl[8] * proj[2] + modl[9] * proj[6] + modl[10] * proj[10] + modl[11] * proj[14];
+	clip[11] = modl[8] * proj[3] + modl[9] * proj[7] + modl[10] * proj[11] + modl[11] * proj[15];
+
+	clip[12] = modl[12] * proj[0] + modl[13] * proj[4] + modl[14] * proj[8] + modl[15] * proj[12];
+	clip[13] = modl[12] * proj[1] + modl[13] * proj[5] + modl[14] * proj[9] + modl[15] * proj[13];
+	clip[14] = modl[12] * proj[2] + modl[13] * proj[6] + modl[14] * proj[10] + modl[15] * proj[14];
+	clip[15] = modl[12] * proj[3] + modl[13] * proj[7] + modl[14] * proj[11] + modl[15] * proj[15];
+
+	frustum_planes[RIGHT][A] = clip[3] - clip[0];
+	frustum_planes[RIGHT][B] = clip[7] - clip[4];
+	frustum_planes[RIGHT][C] = clip[11] - clip[8];
+	frustum_planes[RIGHT][D] = clip[15] - clip[12];
+	normalizePlane(frustum_planes[RIGHT]);
+
+	frustum_planes[LEFT][A] = clip[3] + clip[0];
+	frustum_planes[LEFT][B] = clip[7] + clip[4];
+	frustum_planes[LEFT][C] = clip[11] + clip[8];
+	frustum_planes[LEFT][D] = clip[15] + clip[12];
+	normalizePlane(frustum_planes[LEFT]);
+
+	frustum_planes[BOTTOM][A] = clip[3] + clip[1];
+	frustum_planes[BOTTOM][B] = clip[7] + clip[5];
+	frustum_planes[BOTTOM][C] = clip[11] + clip[9];
+	frustum_planes[BOTTOM][D] = clip[15] + clip[13];
+	normalizePlane(frustum_planes[BOTTOM]);
+
+	frustum_planes[TOP][A] = clip[3] - clip[1];
+	frustum_planes[TOP][B] = clip[7] - clip[5];
+	frustum_planes[TOP][C] = clip[11] - clip[9];
+	frustum_planes[TOP][D] = clip[15] - clip[13];
+	normalizePlane(frustum_planes[TOP]);
+
+	frustum_planes[BACK][A] = clip[3] - clip[2];
+	frustum_planes[BACK][B] = clip[7] - clip[6];
+	frustum_planes[BACK][C] = clip[11] - clip[10];
+	frustum_planes[BACK][D] = clip[15] - clip[14];
+	normalizePlane(frustum_planes[BACK]);
+
+	frustum_planes[FRONT][A] = clip[3] + clip[2];
+	frustum_planes[FRONT][B] = clip[7] + clip[6];
+	frustum_planes[FRONT][C] = clip[11] + clip[10];
+	frustum_planes[FRONT][D] = clip[15] + clip[14];
+	normalizePlane(frustum_planes[FRONT]);
+}
+
+bool Frustum::TestInsideFrustrum(glm::vec4 Min, glm::vec4 Max) {
+	bool inside = true;
+	//test all 6 frustum planes
+	for (int i = 0; i < 6; i++) {
+		//pick closest point to plane and check if it behind the plane
+		//if yes - object outside frustum
+		float d = std::max(Min.x * frustum_planes[i].x, Max.x * frustum_planes[i].x)
+		          + std::max(Min.y * frustum_planes[i].y, Max.y * frustum_planes[i].y)
+		          + std::max(Min.z * frustum_planes[i].z, Max.z * frustum_planes[i].z)
+		          + frustum_planes[i].w;
+		inside &= d > 0;
+		//return false; //with flag works faster
+	}
+	return inside;
+}
diff --git a/src/graphics/Frustrum.hpp b/src/graphics/Frustrum.hpp
new file mode 100644
index 0000000..e8a6fd6
--- /dev/null
+++ b/src/graphics/Frustrum.hpp
@@ -0,0 +1,24 @@
+#ifndef _FRUSTUM_H
+#define _FRUSTUM_H
+
+
+#include <cmath>
+#include <algorithm>
+#include <GL/glew.h>
+#include <glm/glm.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
+class Frustum {
+public:
+	Frustum() = default;
+
+	~Frustum() = default;
+
+	void CalculateFrustum(glm::mat4 &view_matrix, glm::mat4 &proj_matrix);
+
+	glm::vec4 frustum_planes[6];
+
+	bool TestInsideFrustrum(glm::vec4 Min, glm::vec4 Max);
+};
+
+#endif
\ No newline at end of file