#include "geometry.hpp"
+#include <limits>
+
namespace blank {
-bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *dist) {
+bool Intersection(
+ const Ray &ray,
+ const AABB &aabb,
+ const glm::mat4 &M,
+ float *dist,
+ glm::vec3 *normal
+) {
float t_min = 0.0f;
float t_max = 1.0e5f;
const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
const glm::vec3 delta = aabb_pos - ray.orig;
+ glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
+ bool x_swap = false, y_swap = false, z_swap = false;
+
{ // X
const glm::vec3 xaxis(M[0].x, M[0].y, M[0].z);
const float e = glm::dot(xaxis, delta);
const float f = glm::dot(ray.dir, xaxis);
- if (std::abs(f) > 0.001f) {
- float t1 = (e + aabb.min.x) / f;
- float t2 = (e + aabb.max.x) / f;
+ if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
+ t1.x = (e + aabb.min.x) / f;
+ t2.x = (e + aabb.max.x) / f;
- if (t1 > t2) {
- std::swap(t1, t2);
+ if (t1.x > t2.x) {
+ std::swap(t1.x, t2.x);
+ x_swap = true;
}
- if (t1 > t_min) {
- t_min = t1;
+ if (t1.x > t_min) {
+ t_min = t1.x;
}
- if (t2 < t_max) {
- t_max = t2;
+ if (t2.x < t_max) {
+ t_max = t2.x;
}
if (t_max < t_min) {
return false;
const float e = glm::dot(yaxis, delta);
const float f = glm::dot(ray.dir, yaxis);
- if (std::abs(f) > 0.001f) {
- float t1 = (e + aabb.min.y) / f;
- float t2 = (e + aabb.max.y) / f;
+ if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
+ t1.y = (e + aabb.min.y) / f;
+ t2.y = (e + aabb.max.y) / f;
- if (t1 > t2) {
- std::swap(t1, t2);
+ if (t1.y > t2.y) {
+ std::swap(t1.y, t2.y);
+ y_swap = true;
}
- if (t1 > t_min) {
- t_min = t1;
+ if (t1.y > t_min) {
+ t_min = t1.y;
}
- if (t2 < t_max) {
- t_max = t2;
+ if (t2.y < t_max) {
+ t_max = t2.y;
}
if (t_max < t_min) {
return false;
const float e = glm::dot(zaxis, delta);
const float f = glm::dot(ray.dir, zaxis);
- if (std::abs(f) > 0.001f) {
- float t1 = (e + aabb.min.z) / f;
- float t2 = (e + aabb.max.z) / f;
+ if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
+ t1.z = (e + aabb.min.z) / f;
+ t2.z = (e + aabb.max.z) / f;
- if (t1 > t2) {
- std::swap(t1, t2);
+ if (t1.z > t2.z) {
+ std::swap(t1.z, t2.z);
+ z_swap = true;
}
- if (t1 > t_min) {
- t_min = t1;
+ if (t1.z > t_min) {
+ t_min = t1.z;
}
- if (t2 < t_max) {
- t_max = t2;
+ if (t2.z < t_max) {
+ t_max = t2.z;
}
if (t_max < t_min) {
return false;
if (dist) {
*dist = t_min;
}
+ if (normal) {
+ if (t1.x > t1.y) {
+ if (t1.x > t1.z) {
+ *normal = glm::vec3(x_swap ? 1 : -1, 0, 0);
+ } else {
+ *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+ }
+ } else if (t1.y > t1.z) {
+ *normal = glm::vec3(0, y_swap ? 1 : -1, 0);
+ } else {
+ *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+ }
+ }
return true;
}
+bool CullTest(const AABB &box, const glm::mat4 &MVP) {
+ // transform corners into clip space
+ glm::vec4 corners[8] = {
+ { box.min.x, box.min.y, box.min.z, 1.0f },
+ { box.min.x, box.min.y, box.max.z, 1.0f },
+ { box.min.x, box.max.y, box.min.z, 1.0f },
+ { box.min.x, box.max.y, box.max.z, 1.0f },
+ { box.max.x, box.min.y, box.min.z, 1.0f },
+ { box.max.x, box.min.y, box.max.z, 1.0f },
+ { box.max.x, box.max.y, box.min.z, 1.0f },
+ { box.max.x, box.max.y, box.max.z, 1.0f },
+ };
+ for (glm::vec4 &corner : corners) {
+ corner = MVP * corner;
+ corner /= corner.w;
+ }
+
+ int hits[6] = { 0, 0, 0, 0, 0, 0 };
+
+ // check how many corners lie outside
+ for (const glm::vec4 &corner : corners) {
+ if (corner.x > 1.0f) ++hits[0];
+ if (corner.x < -1.0f) ++hits[1];
+ if (corner.y > 1.0f) ++hits[2];
+ if (corner.y < -1.0f) ++hits[3];
+ if (corner.z > 1.0f) ++hits[4];
+ if (corner.z < -1.0f) ++hits[5];
+ }
+
+ // if all corners are outside any given clip plane, the test is true
+ for (int hit : hits) {
+ if (hit == 8) return true;
+ }
+
+ // otherwise the box might still get culled completely, but can't say for sure ;)
+ return false;
+}
+
}