sKit_Example_Shapes.cpp

#define SDL_MAIN_USE_CALLBACKS
 
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
 
#include <glm/common.hpp>
#include <sKit/geom/shapes.hpp>
#include <stdexcept>
#include <vector>
 
const static int width = 1280;
const static int height = 800;
 
struct STATE {
  SDL_Window *w;
  SDL_Renderer *rdr;
};
 
auto SDL_AppInit(void **appstate, int argc, char **argv) -> SDL_AppResult {
  SDL_Init(SDL_INIT_VIDEO);
  auto state = new STATE;
  if (!SDL_CreateWindowAndRenderer(
          "", width, height, SDL_WINDOW_UTILITY, &state->w, &state->rdr
      )) {
    throw std::runtime_error(SDL_GetError());
  };
  *appstate = state;
  return SDL_APP_CONTINUE;
}
 
constexpr float tau = std::numbers::pi_v<float> * 2.f;
 
auto SDL_AppIterate(void *appstate) -> SDL_AppResult {
  auto state = reinterpret_cast<STATE *>(appstate);
 
  SDL_SetRenderDrawColor(state->rdr, 0, 0, 0, 255);
  SDL_RenderClear(state->rdr);
 
  // Generate circle geometry
  auto c = sKit::geom::circle<SDL_Vertex, int>(width / 2.f, height / 2.f, 100);
 
  // Generate arc vertices
  auto arc = sKit::geom::vertex::arc<SDL_FPoint>(
      width / 3.f,
      height / 3.f,
      100,
      glm::fract(SDL_GetTicks() * 0.0003) * tau,
      sKit::math::map(sin(SDL_GetTicks() * 0.0005), -1, 1, 0.2, tau),
      sKit::math::map(cos(SDL_GetTicks() * 0.0004), -1, 1, 25, 75)
  );
 
  // Render circle geometry
  SDL_RenderGeometry(
      state->rdr,
      nullptr,
      c.vertices.data(),
      c.vertices.size(),
      c.indices.data(),
      c.indices.size()
  );
 
  // Render arc vertices as line
  SDL_SetRenderDrawColor(state->rdr, 255, 255, 255, 255);
  SDL_RenderLines(state->rdr, arc.data(), arc.size());
 
  SDL_RenderPresent(state->rdr);
  return SDL_APP_CONTINUE;
}
 
auto SDL_AppEvent(void *appstate, SDL_Event *event) -> SDL_AppResult {
  if (event->type == SDL_EVENT_QUIT) {
    return SDL_APP_SUCCESS;
  } else if (event->key.key == SDLK_ESCAPE) {
    return SDL_APP_SUCCESS;
  } else
    return SDL_APP_CONTINUE;
}
 
void SDL_AppQuit(void *appstate, SDL_AppResult result) {
  delete reinterpret_cast<STATE *>(appstate);
}