empty SDL3 time accum loop

sdl3_template.cpp

#include <SDL3/SDL.h>
#include <iostream>
#include <cstdint>
#include <cassert>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <utility>
#include <algorithm>
#include <string>



int main(int argc, char const *argv[])
{
    if (!SDL_Init(SDL_INIT_VIDEO)) {
        std::cerr << "Initialization failed: " << SDL_GetError() << "\n";
        return -1;
    }

    SDL_Window* window = nullptr;
    SDL_Renderer* renderer = nullptr;
    if (!SDL_CreateWindowAndRenderer("The Modern Black Swordsman", SQ_CAM_X_PX, SQ_CAM_Y_PX, 0, &window, &renderer)) {
        std::cerr << "Failed to create window/renderer: " << SDL_GetError() << "\n";
        return -1;
    }

    bool running = true;

    // Fixed timestep setup (60 updates per second)
    const Uint64 FIXED_DELTA_TIME_NS = 1000000000 / 60; 
    Uint64 current_time_ns = SDL_GetTicksNS();
    Uint64 previous_time_ns = current_time_ns;
    Uint64 accumulator_ns = 0;

    while (running) {
        current_time_ns = SDL_GetTicksNS();
        Uint64 elapsed_ns = current_time_ns - previous_time_ns;
        previous_time_ns = current_time_ns;

        if (elapsed_ns > 250000000) elapsed_ns = 250000000;
        accumulator_ns += elapsed_ns;

        // ==========================================
        // 1. INPUT DETECTION (OS Events & Mouse)
        // ==========================================
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_EVENT_QUIT) { 
                running = false;
            }
            
            // Detect Mouse Clicks in SDL3
            else if (event.type == SDL_EVENT_MOUSE_BUTTON_DOWN) {
                if (event.button.button == SDL_BUTTON_LEFT) {
                    // SDL3 provides mouse coordinates as clean floats
                    float mousepre_x = event.button.x;
                    float mousepre_y = event.button.y;

                    std::cout << "Clicked x=" << mousepre_x << ", y=" << mousepre_y  << "\n";


                }
            }
        }

        // ==========================================
        // 2. FIXED PHYSICS / LOGIC TIMESTEP
        // ==========================================
        while (accumulator_ns >= FIXED_DELTA_TIME_NS) {
            // Update item animations, physics, and skilling timers here
            //playerPathMover.moveSprite();
            // based on path, change target.
            accumulator_ns -= FIXED_DELTA_TIME_NS;
        }

        // ==========================================
        // 3. PAINT / RENDERING THE WINDOW
        // ==========================================
        // A. Wipe the canvas clean with background color (Dark Berserk Charcoal)
        SDL_SetRenderDrawColor(renderer, 20, 20, 20, 255);
        SDL_RenderClear(renderer);


        //SDL_RenderFillRect(renderer, &specrect);
    
        
        // C. Command the GPU to push the backbuffer into the visible monitor frame
        SDL_RenderPresent(renderer);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();
	return 0;
}