// Copyright (c) 2024 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "SphereMesh.hpp"

using namespace Dawn;

void SphereMesh::create(
  std::shared_ptr<Mesh> mesh,
  const float radius,
  const uint32_t segments,
  const uint32_t rings
) {
  // Create the vertices
  std::vector<glm::vec3> vertices;
  for(uint32_t r = 0; r < rings; ++r) {
    for(uint32_t s = 0; s < segments; ++s) {
      float const y = sin(-M_PI_2 + M_PI * r / rings);
      float const x = cos(2 * M_PI * s / segments) * sin(M_PI * r / rings);
      float const z = sin(2 * M_PI * s / segments) * sin(M_PI * r / rings);
      vertices.push_back(glm::vec3(x, y, z) * radius);
    }
  }

  // Create the indices
  std::vector<int32_t> indices;
  for(uint32_t r = 0; r < rings - 1; ++r) {
    for(uint32_t s = 0; s < segments - 1; ++s) {
      indices.push_back(r * segments + s);
      indices.push_back(r * segments + (s + 1));
      indices.push_back((r + 1) * segments + (s + 1));

      indices.push_back(r * segments + s);
      indices.push_back((r + 1) * segments + (s + 1));
      indices.push_back((r + 1) * segments + s);
    }
  }

  mesh->createBuffers(vertices.size(), indices.size());
  mesh->bufferPositions(0, vertices.data(), vertices.size());
  mesh->bufferIndices(0, indices.data(), indices.size());
}