Initial commit
This commit is contained in:
Michael Smith
288
code/platform.cpp
Normal file
288
code/platform.cpp
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#include "rt_weekend.h"
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#include <SDL.h>
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#include <stdio.h>
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#include <sys/mman.h>
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#include <stdbool.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <dlfcn.h>
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#include "platform.h"
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const char *WindowTitle = "Ray Tracing in a Weekend";
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const uint32_t TARGET_FRAME_RATE = 30;
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const uint32_t TICKS_PER_FRAME = 1000 / TARGET_FRAME_RATE;
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const uint32_t WINDOW_WIDTH = 500;
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const uint32_t WINDOW_HEIGHT = 250;
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global_variable bool Running = true;
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global_variable sdl_offscreen_buffer GlobalBackbuffer;
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void PluginUpdateAndRenderStub(plugin_offscreen_buffer *Buffer)
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{
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}
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internal sdl_window_dimension
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SDLGetWindowDimension(SDL_Window *Window)
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{
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sdl_window_dimension Result;
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SDL_GetWindowSize(Window, &Result.Width, &Result.Height);
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return(Result);
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}
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internal void
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SDLResizeTexture(sdl_offscreen_buffer *Buffer,
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SDL_Renderer *Renderer,
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int Width, int Height)
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{
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const int BytesPerPixel = 4;
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if(Buffer->Memory)
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{
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munmap(Buffer->Memory,
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Buffer->Height * Buffer->Pitch);
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}
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if(Buffer->Texture)
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{
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SDL_DestroyTexture(Buffer->Texture);
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}
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Buffer->Texture = SDL_CreateTexture(Renderer,
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SDL_PIXELFORMAT_RGBA8888,
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SDL_TEXTUREACCESS_STREAMING,
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Width, Height);
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Buffer->Width = Width;
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Buffer->Height = Height;
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Buffer->Pitch = Width * BytesPerPixel;
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Buffer->Memory = mmap(0, Width * Height * BytesPerPixel,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS,
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-1, 0);
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}
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internal void
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SDLUpdateWindow(SDL_Renderer *Renderer,
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sdl_offscreen_buffer Buffer)
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{
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SDL_UpdateTexture(Buffer.Texture,
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0,
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Buffer.Memory,
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Buffer.Pitch);
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SDL_RenderCopy(Renderer, Buffer.Texture, 0, 0);
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SDL_RenderPresent(Renderer);
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}
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internal void
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HandleEvent(SDL_Event *Event)
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{
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switch(Event->type)
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{
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case SDL_QUIT:
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{
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Running = false;
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} break;
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case SDL_WINDOWEVENT:
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{
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switch (Event->window.event)
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{
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case SDL_WINDOWEVENT_EXPOSED:
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{
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SDL_Window *Window = SDL_GetWindowFromID(Event->window.windowID);
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SDL_Renderer *Renderer = SDL_GetRenderer(Window);
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SDLUpdateWindow(Renderer, GlobalBackbuffer);
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} break;
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}
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}
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}
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}
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inline time_t
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SDLGetLastModificationTime(const char *Filename)
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{
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time_t LastModificationTime = 0;
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// Find out plugin library's last modification time
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struct stat LibraryFileStat;
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if (stat(Filename, &LibraryFileStat) == 0)
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{
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LastModificationTime = LibraryFileStat.st_ctime;
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}
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else
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{
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printf("Could not read plugin library: %s\n", strerror(errno));
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}
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return(LastModificationTime);
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}
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internal sdl_plugin_code
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SDLLoadPluginCode(const char *Filename)
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{
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sdl_plugin_code Result = {};
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Result.UpdateAndRender = PluginUpdateAndRenderStub;
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Result.LastModificationTime = SDLGetLastModificationTime(Filename);
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const char *error;
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/* Load library */
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Result.CodeLibrary = dlopen(Filename, RTLD_LAZY);
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if (Result.CodeLibrary)
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{
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dlerror();
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Result.UpdateAndRender =
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(plugin_update_and_render *)dlsym(Result.CodeLibrary,
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"PluginUpdateAndRender");
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if ((error = dlerror()))
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{
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fprintf(stderr, "Couldn't find PluginUpdateAndRender: %s\n", error);
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}
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}
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else
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{
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fprintf(stderr, "Couldn't open plugin library: %s\n",
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dlerror());
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}
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return(Result);
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}
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internal void
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SDLUnloadPluginCode(sdl_plugin_code *Plugin)
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{
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if(Plugin->CodeLibrary)
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{
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dlclose(Plugin->CodeLibrary);
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}
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Plugin->UpdateAndRender = PluginUpdateAndRenderStub;
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}
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int main()
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{
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// Variables required to calculate framerate
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#define FPS_INTERVAL 1.0
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uint32_t LastFrameEndTime = SDL_GetTicks();
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uint32_t CurrentFPS = 0;
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uint32_t FramesElapsed = 0;
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uint32_t FramesMissed = 0;
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// Initialize SDL
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SDL_Window *Window = NULL;
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SDL_Renderer *Renderer = NULL;
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if (SDL_Init(SDL_INIT_VIDEO) != 0)
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{
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SDL_Log("Unable to initialize SDL: %s", SDL_GetError());
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return 1;
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}
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// Create window
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Window = SDL_CreateWindow(WindowTitle,
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SDL_WINDOWPOS_UNDEFINED,
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SDL_WINDOWPOS_UNDEFINED,
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WINDOW_WIDTH,
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WINDOW_HEIGHT,
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SDL_WINDOW_OPENGL);
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if (Window == NULL)
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{
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printf("Could not create window: %s\n", SDL_GetError());
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SDL_Quit();
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return 1;
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}
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// Create renderer
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Renderer = SDL_CreateRenderer(Window, -1, SDL_RENDERER_ACCELERATED);
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if (Renderer == NULL)
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{
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printf("Could not create renderer: %s\n", SDL_GetError());
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SDL_DestroyWindow(Window);
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SDL_Quit();
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return 1;
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}
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// Create texture
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sdl_window_dimension Dimension = SDLGetWindowDimension(Window);
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SDLResizeTexture(&GlobalBackbuffer, Renderer, Dimension.Width, Dimension.Height);
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// Load plugin code
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const char *PluginLibraryFilename = "librt_weekend.so";
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sdl_plugin_code Plugin = SDLLoadPluginCode(PluginLibraryFilename);
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// Main loop
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while (Running)
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{
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uint32_t FrameStartTime = SDL_GetTicks();
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// Live reloading
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time_t NewLastModificationTime = SDLGetLastModificationTime(PluginLibraryFilename);
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if(NewLastModificationTime > Plugin.LastModificationTime)
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{
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SDLUnloadPluginCode(&Plugin);
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Plugin = SDLLoadPluginCode(PluginLibraryFilename);
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}
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SDL_Event Event;
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while (SDL_PollEvent(&Event))
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{
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HandleEvent(&Event);
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}
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// Display rendering information in Window title
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char WindowTitleBuffer[512];
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sprintf(WindowTitleBuffer,
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"%s - %d x %d - %u fps - %d frames missed",
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WindowTitle,
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WINDOW_WIDTH,
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WINDOW_HEIGHT,
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CurrentFPS,
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FramesMissed);
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SDL_SetWindowTitle(Window, WindowTitleBuffer);
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plugin_offscreen_buffer Buffer = {};
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Buffer.Memory = GlobalBackbuffer.Memory;
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Buffer.Width = GlobalBackbuffer.Width;
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Buffer.Height = GlobalBackbuffer.Height;
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Buffer.Pitch = GlobalBackbuffer.Pitch;
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Plugin.UpdateAndRender(&Buffer);
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SDLUpdateWindow(Renderer, GlobalBackbuffer);
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uint32_t FrameEndTime = SDL_GetTicks();
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// Calculate framerate
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if (LastFrameEndTime < FrameEndTime - FPS_INTERVAL * 1000)
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{
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LastFrameEndTime = FrameEndTime;
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CurrentFPS = FramesElapsed;
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FramesElapsed = 0;
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}
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FramesElapsed++;
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// Cap framerate
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uint32_t FrameTicks = FrameEndTime - FrameStartTime;
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if (FrameTicks < TICKS_PER_FRAME)
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{
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// Wait remaining time
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SDL_Delay(TICKS_PER_FRAME - FrameTicks);
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}
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else
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{
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FramesMissed++;
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}
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}
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SDL_DestroyRenderer(Renderer);
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SDL_DestroyWindow(Window);
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SDL_Quit();
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return 0;
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}
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