#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
+) noexcept {
float t_min = 0.0f;
- float t_max = 1.0e5f;
+ float t_max = std::numeric_limits<float>::infinity();
const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
const glm::vec3 delta = aabb_pos - ray.orig;
- { // 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);
+ glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
- if (std::abs(f) > 0.001f) {
- float t1 = (e + aabb.min.x) / f;
- float t2 = (e + aabb.max.x) / f;
+ for (int i = 0; i < 3; ++i) {
+ const glm::vec3 axis(M[i].x, M[i].y, M[i].z);
+ const float e = glm::dot(axis, delta);
+ const float f = glm::dot(axis, ray.dir);
+
+ if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
+ t1[i] = (e + aabb.min[i]) / f;
+ t2[i] = (e + aabb.max[i]) / f;
+
+ t_min = std::max(t_min, std::min(t1[i], t2[i]));
+ t_max = std::min(t_max, std::max(t1[i], t2[i]));
- if (t1 > t2) {
- std::swap(t1, t2);
- }
- if (t1 > t_min) {
- t_min = t1;
- }
- if (t2 < t_max) {
- t_max = t2;
- }
if (t_max < t_min) {
return false;
}
} else {
- if (aabb.min.x - e > 0.0f || aabb.max.x < 0.0f) {
+ if (aabb.min[i] - e < 0.0f || -aabb.max[i] - e > 0.0f) {
return false;
}
}
}
- { // Y
- const glm::vec3 yaxis(M[1].x, M[1].y, M[1].z);
- 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;
+ glm::vec3 min_all(min(t1, t2));
- if (t1 > t2) {
- std::swap(t1, t2);
- }
- if (t1 > t_min) {
- t_min = t1;
- }
- if (t2 < t_max) {
- t_max = t2;
- }
- if (t_max < t_min) {
- return false;
+ if (dist) {
+ *dist = t_min;
+ }
+ if (normal) {
+ glm::vec4 norm(0.0f);
+ if (min_all.x > min_all.y) {
+ if (min_all.x > min_all.z) {
+ norm.x = t2.x < t1.x ? 1 : -1;
+ } else {
+ norm.z = t2.z < t1.z ? 1 : -1;
}
+ } else if (min_all.y > min_all.z) {
+ norm.y = t2.y < t1.y ? 1 : -1;
} else {
- if (aabb.min.y - e > 0.0f || aabb.max.y < 0.0f) {
- return false;
- }
+ norm.z = t2.z < t1.z ? 1 : -1;
}
+ norm = M * norm;
+ *normal = glm::vec3(norm);
}
+ return true;
+}
- { // Z
- const glm::vec3 zaxis(M[2].x, M[2].y, M[2].z);
- const float e = glm::dot(zaxis, delta);
- const float f = glm::dot(ray.dir, zaxis);
+bool CullTest(const AABB &box, const glm::mat4 &MVP) noexcept {
+ // 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;
+ }
- if (std::abs(f) > 0.001f) {
- float t1 = (e + aabb.min.z) / f;
- float t2 = (e + aabb.max.z) / f;
+ int hits[6] = { 0, 0, 0, 0, 0, 0 };
- if (t1 > t2) {
- std::swap(t1, t2);
- }
- if (t1 > t_min) {
- t_min = t1;
- }
- if (t2 < t_max) {
- t_max = t2;
- }
- if (t_max < t_min) {
- return false;
- }
- } else {
- if (aabb.min.z - e > 0.0f || aabb.max.z < 0.0f) {
- return false;
- }
- }
+ // 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 (dist) {
- *dist = t_min;
+ // if all corners are outside any given clip plane, the test is true
+ for (int hit : hits) {
+ if (hit == 8) return true;
}
- return true;
+
+ // otherwise the box might still get culled completely, but can't say for sure ;)
+ return false;
}
}
projects / blank.git / blobdiff