diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index ec38246fab..78bbd78d09 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -126,6 +126,7 @@ add_sdl_example_executable(renderer-lines SOURCES renderer/03-lines/renderer-lin add_sdl_example_executable(renderer-points SOURCES renderer/04-points/renderer-points.c) add_sdl_example_executable(renderer-rectangles SOURCES renderer/05-rectangles/renderer-rectangles.c) add_sdl_example_executable(renderer-textures SOURCES renderer/06-textures/renderer-textures.c) +add_sdl_example_executable(renderer-streaming-textures SOURCES renderer/07-streaming-textures/renderer-streaming-textures.c) add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playback/simple-playback.c) add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simple-playback-callback/simple-playback-callback.c) add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav) diff --git a/examples/renderer/07-streaming-textures/README.txt b/examples/renderer/07-streaming-textures/README.txt new file mode 100644 index 0000000000..c2505719af --- /dev/null +++ b/examples/renderer/07-streaming-textures/README.txt @@ -0,0 +1,3 @@ +This example creates an SDL window and renderer, then a streaming texture that +it will update every frame before drawing it to the screen. + diff --git a/examples/renderer/07-streaming-textures/renderer-streaming-textures.c b/examples/renderer/07-streaming-textures/renderer-streaming-textures.c new file mode 100644 index 0000000000..994efd7718 --- /dev/null +++ b/examples/renderer/07-streaming-textures/renderer-streaming-textures.c @@ -0,0 +1,106 @@ +/* + * This example creates an SDL window and renderer, and then draws a streaming + * texture to it every frame. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ +#include +#include + +/* We will use this renderer to draw into this window every frame. */ +static SDL_Window *window = NULL; +static SDL_Renderer *renderer = NULL; +static SDL_Texture *texture = NULL; + +#define TEXTURE_SIZE 150 + +#define WINDOW_WIDTH 640 +#define WINDOW_HEIGHT 480 + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + if (!SDL_Init(SDL_INIT_VIDEO)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't initialize SDL!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/renderer/streaming-textures", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, TEXTURE_SIZE, TEXTURE_SIZE); + if (!texture) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create streaming texture!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ +SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) +{ + if (event->type == SDL_EVENT_QUIT) { + return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ + } + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once per frame, and is the heart of the program. */ +SDL_AppResult SDL_AppIterate(void *appstate) +{ + SDL_FRect dst_rect; + const Uint64 now = SDL_GetTicks(); + SDL_Surface *surface = NULL; + + /* we'll have some color move around over a few seconds. */ + const float direction = ((now % 2000) >= 1000) ? 1.0f : -1.0f; + const float scale = ((float) (((int) (now % 1000)) - 500) / 500.0f) * direction; + + /* To update a streaming texture, you need to lock it first. This gets you access to the pixels. + Note that this is considered a _write-only_ operation: the buffer you get from locking + might not acutally have the existing contents of the texture, and you have to write to every + locked pixel! */ + + /* You can use SDL_LockTexture() to get an array of raw pixels, but we're going to use + SDL_LockTextureToSurface() here, because it wraps that array in a temporary SDL_Surface, + letting us use the surface drawing functions instead of lighting up individual pixels. */ + if (SDL_LockTextureToSurface(texture, NULL, &surface)) { + SDL_Rect r; + SDL_FillSurfaceRect(surface, NULL, SDL_MapRGB(SDL_GetPixelFormatDetails(surface->format), NULL, 0, 0, 0)); /* make the whole surface black */ + r.w = TEXTURE_SIZE; + r.h = TEXTURE_SIZE / 10; + r.x = 0; + r.y = (int) (((float) (TEXTURE_SIZE - r.h)) * ((scale + 1.0f) / 2.0f)); + SDL_FillSurfaceRect(surface, &r, SDL_MapRGB(SDL_GetPixelFormatDetails(surface->format), NULL, 0, 255, 0)); /* make a strip of the surface green */ + SDL_UnlockTexture(texture); /* upload the changes (and frees the temporary surface)! */ + } + + /* as you can see from this, rendering draws over whatever was drawn before it. */ + SDL_SetRenderDrawColor(renderer, 66, 66, 66, 255); /* grey, full alpha */ + SDL_RenderClear(renderer); /* start with a blank canvas. */ + + /* Just draw the static texture a few times. You can think of it like a + stamp, there isn't a limit to the number of times you can draw with it. */ + + /* Center this one. It'll draw the latest version of the texture we drew while it was locked. */ + dst_rect.x = ((float) (WINDOW_WIDTH - TEXTURE_SIZE)) / 2.0f; + dst_rect.y = ((float) (WINDOW_HEIGHT - TEXTURE_SIZE)) / 2.0f; + dst_rect.w = dst_rect.h = (float) TEXTURE_SIZE; + SDL_RenderTexture(renderer, texture, NULL, &dst_rect); + + SDL_RenderPresent(renderer); /* put it all on the screen! */ + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate) +{ + /* SDL will clean up the window/renderer for us. */ +} +