80 lines
1.9 KiB
C++
80 lines
1.9 KiB
C++
#pragma once
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#include <glm/glm.hpp>
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#include <vector>
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#include <algorithm>
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glm::vec4 round(glm::vec4 f, int prec) {
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auto dec = (float) pow(10, prec);
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auto res = glm::trunc(f * dec + 0.5f) / dec;
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return res;
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}
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float dot(int n, glm::vec4 a, glm::vec4 b) {
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float sum = 0;
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for (int i = 0; i < n; ++i) {
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sum += a[i] * b[i];
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}
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return sum;
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}
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glm::vec4 project(glm::vec4 vec, glm::vec4 target) {
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return glm::dot(vec, target) / glm::dot(target, target) * target;
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}
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glm::vec4 reflect(glm::vec4 vec, glm::vec4 axis) {
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return vec - 2.0f * project(vec, axis);
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}
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glm::vec4 gram_schmidt_last(std::vector<glm::vec4> vecs) {
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int N = vecs.size();
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for (int i = 0; i < N; ++i) {
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for (int j = 0; j < i; ++j) {
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vecs[i] -= project(vecs[i], vecs[j]);
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}
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}
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return glm::normalize(vecs[N - 1]);
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}
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glm::vec4 barycentric(std::vector<glm::vec4> basis, std::vector<float> coords) {
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glm::vec4 res{};
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int N = std::min(basis.size(), coords.size());
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for (int i = 0; i < N; ++i) {
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res += basis[i] * coords[i];
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}
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return glm::normalize(res);
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}
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std::vector<glm::vec4> plane_intersections(std::vector<glm::vec4> normals) {
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int N = normals.size();
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std::vector<glm::vec4> results(N);
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for (int i = 0; i < N; ++i) {
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std::rotate(normals.begin(), normals.begin() + 1, normals.end());
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results[i] = gram_schmidt_last(normals);
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}
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return results;
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}
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std::vector<std::vector<int>> combinations(int N, int K) {
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std::string bitmask(K, 1); // K leading 1's
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bitmask.resize(N, 0); // N-K trailing 0's
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std::vector<std::vector<int>> combos{};
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do {
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std::vector<int> combo{};
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for (int i = 0; i < N; ++i) // [0..N-1] integers
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{
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if (bitmask[i]) {
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combo.push_back(i);
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}
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}
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combos.push_back(combo);
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} while (std::prev_permutation(bitmask.begin(), bitmask.end()));
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return combos;
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}
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