utilities; fix cmakelists typo

cosets/src/util/numeric.hpp

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <glm/glm.hpp>
+#include <vector>
+#include <algorithm>
 
 glm::vec4 round(glm::vec4 f, int prec) {
    auto dec = (float) pow(10, prec);
@@ -15,3 +17,43 @@ float dot(int n, glm::vec4 a, glm::vec4 b) {
    }
    return sum;
 }
+
+glm::vec4 project(glm::vec4 vec, glm::vec4 target) {
+   return glm::dot(vec, target) / glm::dot(target, target) * target;
+}
+
+glm::vec4 reflect(glm::vec4 vec, glm::vec4 axis) {
+   return vec - 2.0f * project(vec, axis);
+}
+
+glm::vec4 gram_schmidt_last(std::vector<glm::vec4> vecs) {
+   int N = vecs.size();
+   for (int i = 0; i < N; ++i) {
+      for (int j = 0; j < i; ++j) {
+         vecs[i] -= project(vecs[i], vecs[j]);
+      }
+   }
+
+   return glm::normalize(vecs[N - 1]);
+}
+
+glm::vec4 barycentric(std::vector<glm::vec4> basis, std::vector<float> coords) {
+   glm::vec4 res{};
+   int N = std::min(basis.size(), coords.size());
+   for (int i = 0; i < N; ++i) {
+      res += basis[i] * coords[i];
+   }
+   return res;
+}
+
+std::vector<glm::vec4> plane_intersections(std::vector<glm::vec4> normals) {
+   int N = normals.size();
+   std::vector<glm::vec4> results(N);
+
+   for (int i = 0; i < N; ++i) {
+      results[i] = gram_schmidt_last(normals);
+      std::rotate(normals.begin(), normals.begin() + 1, normals.end());
+   }
+
+   return results;
+}