mirror of
https://github.com/thunderbrewhq/thunderbrew
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110 lines
4.5 KiB
C
110 lines
4.5 KiB
C
/*
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* This example creates an SDL window and renderer, and then draws a streaming
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* texture to it every frame.
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*
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* This code is public domain. Feel free to use it for any purpose!
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*/
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#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */
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#include <SDL3/SDL.h>
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#include <SDL3/SDL_main.h>
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/* We will use this renderer to draw into this window every frame. */
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static SDL_Window *window = NULL;
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static SDL_Renderer *renderer = NULL;
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static SDL_Texture *texture = NULL;
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#define TEXTURE_SIZE 150
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#define WINDOW_WIDTH 640
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#define WINDOW_HEIGHT 480
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/* This function runs once at startup. */
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SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
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{
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SDL_SetAppMetadata("Example Renderer Streaming Textures", "1.0", "com.example.renderer-streaming-textures");
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if (!SDL_Init(SDL_INIT_VIDEO)) {
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SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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if (!SDL_CreateWindowAndRenderer("examples/renderer/streaming-textures", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) {
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SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, TEXTURE_SIZE, TEXTURE_SIZE);
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if (!texture) {
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SDL_Log("Couldn't create streaming texture: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs when a new event (mouse input, keypresses, etc) occurs. */
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SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
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{
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if (event->type == SDL_EVENT_QUIT) {
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return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */
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}
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs once per frame, and is the heart of the program. */
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SDL_AppResult SDL_AppIterate(void *appstate)
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{
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SDL_FRect dst_rect;
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const Uint64 now = SDL_GetTicks();
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SDL_Surface *surface = NULL;
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/* we'll have some color move around over a few seconds. */
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const float direction = ((now % 2000) >= 1000) ? 1.0f : -1.0f;
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const float scale = ((float) (((int) (now % 1000)) - 500) / 500.0f) * direction;
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/* To update a streaming texture, you need to lock it first. This gets you access to the pixels.
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Note that this is considered a _write-only_ operation: the buffer you get from locking
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might not acutally have the existing contents of the texture, and you have to write to every
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locked pixel! */
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/* You can use SDL_LockTexture() to get an array of raw pixels, but we're going to use
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SDL_LockTextureToSurface() here, because it wraps that array in a temporary SDL_Surface,
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letting us use the surface drawing functions instead of lighting up individual pixels. */
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if (SDL_LockTextureToSurface(texture, NULL, &surface)) {
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SDL_Rect r;
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SDL_FillSurfaceRect(surface, NULL, SDL_MapRGB(SDL_GetPixelFormatDetails(surface->format), NULL, 0, 0, 0)); /* make the whole surface black */
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r.w = TEXTURE_SIZE;
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r.h = TEXTURE_SIZE / 10;
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r.x = 0;
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r.y = (int) (((float) (TEXTURE_SIZE - r.h)) * ((scale + 1.0f) / 2.0f));
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SDL_FillSurfaceRect(surface, &r, SDL_MapRGB(SDL_GetPixelFormatDetails(surface->format), NULL, 0, 255, 0)); /* make a strip of the surface green */
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SDL_UnlockTexture(texture); /* upload the changes (and frees the temporary surface)! */
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}
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/* as you can see from this, rendering draws over whatever was drawn before it. */
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SDL_SetRenderDrawColor(renderer, 66, 66, 66, SDL_ALPHA_OPAQUE); /* grey, full alpha */
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SDL_RenderClear(renderer); /* start with a blank canvas. */
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/* Just draw the static texture a few times. You can think of it like a
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stamp, there isn't a limit to the number of times you can draw with it. */
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/* Center this one. It'll draw the latest version of the texture we drew while it was locked. */
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dst_rect.x = ((float) (WINDOW_WIDTH - TEXTURE_SIZE)) / 2.0f;
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dst_rect.y = ((float) (WINDOW_HEIGHT - TEXTURE_SIZE)) / 2.0f;
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dst_rect.w = dst_rect.h = (float) TEXTURE_SIZE;
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SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
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SDL_RenderPresent(renderer); /* put it all on the screen! */
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs once at shutdown. */
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void SDL_AppQuit(void *appstate, SDL_AppResult result)
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{
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SDL_DestroyTexture(texture);
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/* SDL will clean up the window/renderer for us. */
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}
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