shapes.cpp

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#include "shapes.hpp"
 
namespace sKit {
namespace geom {
 
template <>
auto circle<SDL_Vertex>(float x, float y, float radius, unsigned int resolution)
    -> Geometry<SDL_Vertex, int> {
  std::vector<SDL_Vertex> vertices;
  std::vector<int> indices;
  vertices.push_back(SDL_Vertex {.position = {x, y}, .color = {1, 1, 1, 1}});
  auto resf = static_cast<float>(resolution);
  for (int i = 0; i < resolution; i++) {
    float xp = cos(i / resf * std::numbers::pi_v<float> * 2.f) * radius +
               vertices[0].position.x;
    float yp = sin(i / resf * std::numbers::pi_v<float> * 2.f) * radius +
               vertices[0].position.y;
    vertices.emplace_back(
        SDL_Vertex {.position = {xp, yp}, .color = {1, 1, 1, 1}}
    );
    indices.push_back(0);
    indices.push_back(i + 1);
    indices.push_back(((i + 2) % resolution) + 1);
  }
  return Geometry {vertices, indices};
}
auto arc(
    float x,
    float y,
    float radius,
    float theta,
    float width,
    float height,
    unsigned int resolution,
    SDL_FColor col
) -> Geometry<SDL_Vertex, int> {
  static constexpr auto tau = std::numbers::pi_v<float> * 2.f;
  const float resf = static_cast<float>(resolution);
  const unsigned int arcRes = round((width / tau) * resf);
  std::vector<SDL_Vertex> vertices;
  std::vector<int> indices;
  /* if (height > 1 && width > (tau / resf) && */
  /*     arcRes != 0) {  // dont return arcs smaller than a pixel */
    vertices.resize(arcRes * 2 + 2);
    for (unsigned int i = 0; i <= arcRes; i++) {
      const float a = sKit::math::map(i, 0, arcRes, theta, theta + width);
      {
        const float px = cos(a) * (radius - height) + x;
        const float py = sin(a) * (radius - height) + y;
        vertices[i * 2] = SDL_Vertex {.position = {px, py}, .color = col};
      }
      {
        const float px = cos(a) * (radius + 2) + x;
        const float py = sin(a) * (radius + 2) + y;
        vertices[i * 2 + 1] = SDL_Vertex {.position = {px, py}, .color = col};
      }
    }
    for (unsigned int i = 0; i < arcRes * 2; ++i) {
      indices.push_back(i);
      indices.push_back(i + 1);
      indices.push_back(i + 2);
    }
  /* } */
 
  return Geometry {.vertices = vertices, .indices = indices};
};
 
}  // namespace geom
}  // namespace sKit