--- /dev/null
+#include "const.hpp"
+#include "distance.hpp"
+#include "primitive.hpp"
+#include "rotation.hpp"
+
+#include <limits>
+#include <glm/gtx/matrix_cross_product.hpp>
+#include <glm/gtx/optimum_pow.hpp>
+#include <glm/gtx/transform.hpp>
+
+
+namespace blank {
+
+glm::mat3 find_rotation(const glm::vec3 &a, const glm::vec3 &b) noexcept {
+ glm::vec3 v(cross(a, b));
+ if (iszero(v)) {
+ // a and b are parallel
+ if (iszero(a - b)) {
+ // a and b are identical
+ return glm::mat3(1.0f);
+ } else {
+ // a and b are opposite
+ // create arbitrary unit vector perpendicular to a and
+ // rotate 180° around it
+ glm::vec3 arb(a);
+ if (std::abs(a.x - 1.0f) > std::numeric_limits<float>::epsilon()) {
+ arb.x += 1.0f;
+ } else {
+ arb.y += 1.0f;
+ }
+ glm::vec3 axis(normalize(cross(a, arb)));
+ return glm::mat3(glm::rotate(PI, axis));
+ }
+ }
+ float mv = length_squared(v);
+ float c = dot(a, b);
+ float f = (1 - c) / mv;
+ glm::mat3 vx(matrixCross3(v));
+ return glm::mat3(1.0f) + vx + (pow2(vx) * f);
+}
+
+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 = 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;
+
+ glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
+
+ 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 (t_max < t_min) {
+ return false;
+ }
+ } else {
+ if (aabb.min[i] - e > 0.0f || aabb.max[i] - e < 0.0f) {
+ return false;
+ }
+ }
+ }
+
+ glm::vec3 min_all(min(t1, t2));
+
+ if (dist) {
+ *dist = t_min;
+ }
+ if (normal) {
+ if (min_all.x > min_all.y) {
+ if (min_all.x > min_all.z) {
+ normal->x = t2.x < t1.x ? 1 : -1;
+ } else {
+ normal->z = t2.z < t1.z ? 1 : -1;
+ }
+ } else if (min_all.y > min_all.z) {
+ normal->y = t2.y < t1.y ? 1 : -1;
+ } else {
+ normal->z = t2.z < t1.z ? 1 : -1;
+ }
+ }
+ return true;
+}
+
+
+bool Intersection(
+ const AABB &a_box,
+ const glm::mat4 &a_m,
+ const AABB &b_box,
+ const glm::mat4 &b_m,
+ float &depth,
+ glm::vec3 &normal
+) noexcept {
+ glm::vec3 a_corners[8] = {
+ glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.min.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.max.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.min.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.max.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.min.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.max.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.min.z, 1)),
+ glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.max.z, 1)),
+ };
+
+ glm::vec3 b_corners[8] = {
+ glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.min.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.max.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.min.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.max.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.min.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.max.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.min.z, 1)),
+ glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.max.z, 1)),
+ };
+
+ glm::vec3 axes[6] = {
+ glm::vec3(a_m * glm::vec4(1, 0, 0, 0)),
+ glm::vec3(a_m * glm::vec4(0, 1, 0, 0)),
+ glm::vec3(a_m * glm::vec4(0, 0, 1, 0)),
+ glm::vec3(b_m * glm::vec4(1, 0, 0, 0)),
+ glm::vec3(b_m * glm::vec4(0, 1, 0, 0)),
+ glm::vec3(b_m * glm::vec4(0, 0, 1, 0)),
+ };
+
+ depth = std::numeric_limits<float>::infinity();
+ int min_axis = 0;
+
+ int cur_axis = 0;
+ for (const glm::vec3 &axis : axes) {
+ float a_min = std::numeric_limits<float>::infinity();
+ float a_max = -std::numeric_limits<float>::infinity();
+ for (const glm::vec3 &corner : a_corners) {
+ float val = glm::dot(corner, axis);
+ a_min = std::min(a_min, val);
+ a_max = std::max(a_max, val);
+ }
+
+ float b_min = std::numeric_limits<float>::infinity();
+ float b_max = -std::numeric_limits<float>::infinity();
+ for (const glm::vec3 &corner : b_corners) {
+ float val = glm::dot(corner, axis);
+ b_min = std::min(b_min, val);
+ b_max = std::max(b_max, val);
+ }
+
+ if (a_max < b_min || b_max < a_min) return false;
+
+ float overlap = std::min(a_max, b_max) - std::max(a_min, b_min);
+ if (overlap < depth) {
+ depth = overlap;
+ min_axis = cur_axis;
+ }
+
+ ++cur_axis;
+ }
+
+ normal = axes[min_axis];
+ return true;
+}
+
+
+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;
+ }
+
+ 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;
+}
+
+}
projects / blank.git / blobdiff