#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "SDL.h"
#include "SDL_stdinc.h"
#include "SDL_opengl.h"

Include dependency graph for testoffscreen.c:

Functions
void	draw ()

void	save_surface_to_bmp ()

void	loop ()

int	main (int argc, char *argv[])

Variables
static SDL_Renderer *	renderer = NULL

static SDL_Window *	window = NULL

static int	done = SDL_FALSE

static int	frame_number = 0

static int	width = 640

static int	height = 480

static int	max_frames = 200

Function Documentation

◆ draw()

void draw ( )

Definition at line 36 of file testoffscreen.c.

 {
     SDL_Rect Rect;
  
     SDL_SetRenderDrawColor(renderer, 0x10, 0x9A, 0xCE, 0xFF);
     SDL_RenderClear(renderer);
  
     /* Grow based on the frame just to show a difference per frame of the region */
     Rect.x = 0;
     Rect.y = 0;
     Rect.w = (frame_number * 2) % width;
     Rect.h = (frame_number * 2) % height;
     SDL_SetRenderDrawColor(renderer, 0xFF, 0x10, 0x21, 0xFF);
     SDL_RenderFillRect(renderer, &Rect);
  
     SDL_RenderPresent(renderer);
 }

References frame_number, SDL_Rect::h, renderer, SDL_RenderClear, SDL_RenderFillRect, SDL_RenderPresent, SDL_SetRenderDrawColor, SDL_Rect::w, SDL_Rect::x, and SDL_Rect::y.

Referenced by loop().

◆ loop()

void loop ( void )

Definition at line 77 of file testoffscreen.c.

 {
     SDL_Event event;
  
     /* Check for events */
     while (SDL_PollEvent(&event)) {
         switch (event.type) {
             case SDL_QUIT:
             done = SDL_TRUE;
             break;
         }
     }
  
     draw();
     save_surface_to_bmp();
  
 #ifdef __EMSCRIPTEN__
     if (done) {
         emscripten_cancel_main_loop();
     }
 #endif
 }

References done, draw(), save_surface_to_bmp(), SDL_PollEvent, SDL_QUIT, and SDL_TRUE.

Referenced by main().

◆ main()

int main	(	int	argc,
		char *	argv[]
	)

Definition at line 101 of file testoffscreen.c.

 {
     Uint32 then, now, frames;
  
     /* Enable standard application logging */
     SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
  
     /* Force the offscreen renderer, if it cannot be created then fail out */
     if (SDL_VideoInit("offscreen") < 0) {
         SDL_Log("Couldn't initialize the offscreen video driver: %s\n",
             SDL_GetError());
         return SDL_FALSE;
     }
  
         /* If OPENGL fails to init it will fallback to using a framebuffer for rendering */
     window = SDL_CreateWindow("Offscreen Test",
                  SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                  width, height, 0);
  
     if (!window) {
         SDL_Log("Couldn't create window: %s\n",
             SDL_GetError());
         return SDL_FALSE;
     }
  
     renderer = SDL_CreateRenderer(window, -1, 0);
  
     if (!renderer) {
         SDL_Log("Couldn't create renderer: %s\n",
             SDL_GetError());
         return SDL_FALSE;
     }
  
     SDL_RenderClear(renderer);
  
     srand((unsigned int)time(NULL));
  
     /* Main render loop */
     frames = 0;
     then = SDL_GetTicks();
     done = 0;
  
     SDL_Log("Rendering %i frames offscreen\n", max_frames);
  
 #ifdef __EMSCRIPTEN__
     emscripten_set_main_loop(loop, 0, 1);
 #else
     while (!done && frames < max_frames) {
         ++frames;
         loop();
  
         /* Print out some timing information, along with remaining frames */
         if (frames % (max_frames / 10) == 0) {
             now = SDL_GetTicks();
             if (now > then) {
                 double fps = ((double) frames * 1000) / (now - then);
                 SDL_Log("Frames remaining: %i rendering at %2.2f frames per second\n", max_frames - frames, fps);
             }
         }
     }
 #endif
  
     SDL_DestroyRenderer(renderer);
     SDL_DestroyWindow(window);
     SDL_Quit();
  
     return 0;
 }

References done, frames, loop(), max_frames, NULL, renderer, SDL_CreateRenderer, SDL_CreateWindow, SDL_DestroyRenderer, SDL_DestroyWindow, SDL_FALSE, SDL_GetError, SDL_GetTicks(), SDL_Log, SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, SDL_LogSetPriority, SDL_Quit, SDL_RenderClear, SDL_VideoInit, and SDL_WINDOWPOS_UNDEFINED.

◆ save_surface_to_bmp()

void save_surface_to_bmp ( )

Definition at line 55 of file testoffscreen.c.

 {
     SDL_Surface* surface;
     Uint32 r_mask, g_mask, b_mask, a_mask;
     Uint32 pixel_format;
     char file[128];
     int bbp;
  
     pixel_format = SDL_GetWindowPixelFormat(window);
     SDL_PixelFormatEnumToMasks(pixel_format, &bbp, &r_mask, &g_mask, &b_mask, &a_mask);
  
     surface = SDL_CreateRGBSurface(0, width, height, bbp, r_mask, g_mask, b_mask, a_mask);
     SDL_RenderReadPixels(renderer, NULL, pixel_format, (void*)surface->pixels, surface->pitch);
  
     SDL_snprintf(file, sizeof(file), "SDL_window%d-%8.8d.bmp",
         SDL_GetWindowID(window), ++frame_number);
  
     SDL_SaveBMP(surface, file);
     SDL_FreeSurface(surface);
 }