CubicSDR/external/cubicvr2/math/frustum.h

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//
// frustum.h
// CubicVR2
//
// Created by Charles J. Cliffe on 2013-02-22.
// Copyright (c) 2013 Charles J. Cliffe. All rights reserved.
//
#ifndef CubicVR2_frustum_h
#define CubicVR2_frustum_h
#include <vector>
#include "mat4.h"
#include "vec3.h"
#include "vec4.h"
#include "plane.h"
namespace CubicVR {
enum frustum_plane { PLANE_LEFT, PLANE_RIGHT, PLANE_TOP, PLANE_BOTTOM, PLANE_NEAR, PLANE_FAR };
struct frustum {
std::vector<vec4> planes;
vec4 sphere;
frustum() {
planes.resize(6);
for (int i = 0; i < 6; ++i) {
planes[i] = vec4(0, 0, 0, 0);
} //for
} //Frustum::Constructor
void extract(vec3 position, mat4 mvMatrix, mat4 pMatrix) {
mat4 comboMatrix = mat4::multiply(pMatrix, mvMatrix, true);
// Left clipping plane
planes[PLANE_LEFT][0] = comboMatrix[3] + comboMatrix[0];
planes[PLANE_LEFT][1] = comboMatrix[7] + comboMatrix[4];
planes[PLANE_LEFT][2] = comboMatrix[11] + comboMatrix[8];
planes[PLANE_LEFT][3] = comboMatrix[15] + comboMatrix[12];
// Right clipping plane
planes[PLANE_RIGHT][0] = comboMatrix[3] - comboMatrix[0];
planes[PLANE_RIGHT][1] = comboMatrix[7] - comboMatrix[4];
planes[PLANE_RIGHT][2] = comboMatrix[11] - comboMatrix[8];
planes[PLANE_RIGHT][3] = comboMatrix[15] - comboMatrix[12];
// Top clipping plane
planes[PLANE_TOP][0] = comboMatrix[3] - comboMatrix[1];
planes[PLANE_TOP][1] = comboMatrix[7] - comboMatrix[5];
planes[PLANE_TOP][2] = comboMatrix[11] - comboMatrix[9];
planes[PLANE_TOP][3] = comboMatrix[15] - comboMatrix[13];
// Bottom clipping plane
planes[PLANE_BOTTOM][0] = comboMatrix[3] + comboMatrix[1];
planes[PLANE_BOTTOM][1] = comboMatrix[7] + comboMatrix[5];
planes[PLANE_BOTTOM][2] = comboMatrix[11] + comboMatrix[9];
planes[PLANE_BOTTOM][3] = comboMatrix[15] + comboMatrix[13];
// Near clipping plane
planes[PLANE_NEAR][0] = comboMatrix[3] + comboMatrix[2];
planes[PLANE_NEAR][1] = comboMatrix[7] + comboMatrix[6];
planes[PLANE_NEAR][2] = comboMatrix[11] + comboMatrix[10];
planes[PLANE_NEAR][3] = comboMatrix[15] + comboMatrix[14];
// Far clipping plane
planes[PLANE_FAR][0] = comboMatrix[3] - comboMatrix[2];
planes[PLANE_FAR][1] = comboMatrix[7] - comboMatrix[6];
planes[PLANE_FAR][2] = comboMatrix[11] - comboMatrix[10];
planes[PLANE_FAR][3] = comboMatrix[15] - comboMatrix[14];
for (unsigned int i = 0; i < 6; ++i) {
planes[i] = vec4::normalize(planes[i]);
}
//Sphere
__float fov = 1 / pMatrix[5];
__float near = -planes[PLANE_NEAR][3];
__float far = planes[PLANE_FAR][3];
__float view_length = far - near;
__float height = view_length * fov;
__float width = height;
vec3 P(0, 0, near + view_length * 0.5f);
vec3 Q(width, height, near + view_length);
vec3 diff = vec3::subtract(P, Q);
__float diff_mag = vec3::length(diff);
vec3 look_v = vec3(comboMatrix[3], comboMatrix[9], comboMatrix[10]);
__float look_mag = vec3::length(look_v);
look_v = vec3::multiply(look_v, 1 / look_mag);
vec3 pos = vec3(position[0], position[1], position[2]);
pos = vec3::add(pos, vec3::multiply(look_v, view_length * 0.5f));
pos = vec3::add(pos, vec3::multiply(look_v, 1));
sphere = vec4(pos[0], pos[1], pos[2], diff_mag);
}; //Frustum::extract
int contains_sphere(vec4 sphere) {
for (unsigned int i = 0; i < 6; ++i) {
vec4 &p = planes[i];
vec3 normal = vec3(p[0], p[1], p[2]);
__float distance = vec3::dot(normal, vec3(sphere[0],sphere[1],sphere[2])) + p[3];
//OUT
if (distance < -sphere[3]) {
return -1;
}
//INTERSECT
if (fabs(distance) < sphere[3]) {
return 0;
}
} //for
//IN
return 1;
}; //Frustum::contains_sphere
int contains_box(aabb bbox) {
int total_in = 0;
vec3 points[8];
points[0] = bbox.min;
points[1] = vec3(bbox.min[0], bbox.min[1], bbox.max[2]);
points[2] = vec3(bbox.min[0], bbox.max[1], bbox.min[2]);
points[3] = vec3(bbox.min[0], bbox.max[1], bbox.max[2]);
points[4] = vec3(bbox.max[0], bbox.min[1], bbox.min[2]);
points[5] = vec3(bbox.max[0], bbox.min[1], bbox.max[2]);
points[6] = vec3(bbox.max[0], bbox.max[1], bbox.min[2]);
points[7] = bbox.max;
for (unsigned int i = 0; i < 6; ++i) {
unsigned int in_count = 8;
unsigned int point_in = 1;
for (unsigned int j = 0; j < 8; ++j) {
if (plane::classifyPoint(planes[i], points[j]) == -1) {
point_in = 0;
--in_count;
} //if
} //for j
//OUT
if (in_count == 0) {
return -1;
}
total_in += point_in;
} //for i
//IN
if (total_in == 6) {
return 1;
}
return 0;
}; //Frustum::contains_box
};
}
#endif