Atlas - testoffscreen.c
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[FILE BEGIN]
1/*
2  Copyright (C) 1997-2025 Sam Lantinga <[email protected]>
3
4  This software is provided 'as-is', without any express or implied
5  warranty.  In no event will the authors be held liable for any damages
6  arising from the use of this software.
7
8  Permission is granted to anyone to use this software for any purpose,
9  including commercial applications, and to alter it and redistribute it
10  freely.
11*/
12
13/* Simple program: picks the offscreen backend and renders each frame to a png */
14
15#include <SDL3/SDL.h>
16#include <SDL3/SDL_main.h>
17#include <SDL3/SDL_test.h>
18#include <SDL3/SDL_opengl.h>
19
20#ifdef SDL_PLATFORM_EMSCRIPTEN
21#include <emscripten/emscripten.h>
22#endif
23
24static SDL_Renderer *renderer = NULL;
25static SDL_Window *window = NULL;
26static int done = false;
27static int frame_number = 0;
28static int width = 640;
29static int height = 480;
30static unsigned int max_frames = 200;
31
32static void draw(void)
33{
34    SDL_FRect rect;
35
36    SDL_SetRenderDrawColor(renderer, 0x10, 0x9A, 0xCE, 0xFF);
37    SDL_RenderClear(renderer);
38
39    /* Grow based on the frame just to show a difference per frame of the region */
40    rect.x = 0.0f;
41    rect.y = 0.0f;
42    rect.w = (float)((frame_number * 2) % width);
43    rect.h = (float)((frame_number * 2) % height);
44    SDL_SetRenderDrawColor(renderer, 0xFF, 0x10, 0x21, 0xFF);
45    SDL_RenderFillRect(renderer, &rect);
46
47    SDL_RenderPresent(renderer);
48}
49
50static void save_surface_to_png(void)
51{
52    SDL_Surface *surface;
53    char file[128];
54
55    surface = SDL_RenderReadPixels(renderer, NULL);
56
57    (void)SDL_snprintf(file, sizeof(file), "SDL_window%" SDL_PRIs32 "-%8.8d.png",
58                       SDL_GetWindowID(window), ++frame_number);
59
60    SDL_SavePNG(surface, file);
61    SDL_DestroySurface(surface);
62}
63
64static void loop(void)
65{
66    SDL_Event event;
67
68    /* Check for events */
69    while (SDL_PollEvent(&event)) {
70        switch (event.type) {
71        case SDL_EVENT_QUIT:
72            done = true;
73            break;
74        default:
75            break;
76        }
77    }
78
79    draw();
80    save_surface_to_png();
81
82#ifdef SDL_PLATFORM_EMSCRIPTEN
83    if (done) {
84        emscripten_cancel_main_loop();
85    }
86#endif
87}
88
89int main(int argc, char *argv[])
90{
91#ifndef SDL_PLATFORM_EMSCRIPTEN
92    Uint64 then, now;
93    Uint32 frames;
94#endif
95    SDLTest_CommonState *state;
96
97    /* Initialize test framework */
98    state = SDLTest_CommonCreateState(argv, 0);
99    if (!state) {
100        return 1;
101    }
102
103    /* Parse commandline */
104    if (!SDLTest_CommonDefaultArgs(state, argc, argv)) {
105        return 1;
106    }
107
108    /* Force the offscreen renderer, if it cannot be created then fail out */
109    SDL_SetHint(SDL_HINT_VIDEO_DRIVER, "offscreen");
110    if (!SDL_InitSubSystem(SDL_INIT_VIDEO)) {
111        SDL_Log("Couldn't initialize the offscreen video driver: %s",
112                SDL_GetError());
113        return 1;
114    }
115
116    /* If OPENGL fails to init it will fallback to using a framebuffer for rendering */
117    window = SDL_CreateWindow("Offscreen Test", width, height, 0);
118
119    if (!window) {
120        SDL_Log("Couldn't create window: %s", SDL_GetError());
121        return 1;
122    }
123
124    renderer = SDL_CreateRenderer(window, NULL);
125
126    if (!renderer) {
127        SDL_Log("Couldn't create renderer: %s",
128                SDL_GetError());
129        return 1;
130    }
131
132    SDL_RenderClear(renderer);
133
134#ifndef SDL_PLATFORM_EMSCRIPTEN
135    /* Main render loop */
136    frames = 0;
137    then = SDL_GetTicks();
138    done = 0;
139#endif
140
141    SDL_Log("Rendering %u frames offscreen", max_frames);
142
143#ifdef SDL_PLATFORM_EMSCRIPTEN
144    emscripten_set_main_loop(loop, 0, 1);
145#else
146    while (!done && frames < max_frames) {
147        ++frames;
148        loop();
149
150        /* Print out some timing information, along with remaining frames */
151        if (frames % (max_frames / 10) == 0) {
152            now = SDL_GetTicks();
153            if (now > then) {
154                double fps = ((double)frames * 1000) / (now - then);
155                SDL_Log("Frames remaining: %" SDL_PRIu32 " rendering at %2.2f frames per second", max_frames - frames, fps);
156            }
157        }
158    }
159#endif
160
161    SDL_DestroyRenderer(renderer);
162    SDL_DestroyWindow(window);
163    SDL_Quit();
164    SDLTest_CommonDestroyState(state);
165
166    return 0;
167}
168
[FILE END]
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