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#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;
}
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