Squashed 'external/SDL/' content from commit 716c767b7

git-subtree-dir: external/SDL
git-subtree-split: 716c767b7e7099fb0e2fda9db59227a7e1d1d8a4

examples/renderer/11-color-mods/README.txt

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+This example creates an SDL window and renderer, loads a texture from a
+.png file, and then draws it a few times each frame, adjusting the colors.
+

examples/renderer/11-color-mods/color-mods.c

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+/*
+ * This example creates an SDL window and renderer, and then draws some
+ * textures to it every frame, adjusting their color.
+ *
+ * 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 <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+
+/* 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;
+static int texture_width = 0;
+static int texture_height = 0;
+
+#define WINDOW_WIDTH 640
+#define WINDOW_HEIGHT 480
+
+/* This function runs once at startup. */
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+    SDL_Surface *surface = NULL;
+    char *png_path = NULL;
+
+    SDL_SetAppMetadata("Example Renderer Color Mods", "1.0", "com.example.renderer-color-mods");
+
+    if (!SDL_Init(SDL_INIT_VIDEO)) {
+        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    if (!SDL_CreateWindowAndRenderer("examples/renderer/color-mods", WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_RESIZABLE, &window, &renderer)) {
+        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+    SDL_SetRenderLogicalPresentation(renderer, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_LOGICAL_PRESENTATION_LETTERBOX);
+
+    /* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D
+       engines refer to these as "sprites." We'll do a static texture (upload once, draw many
+       times) with data from a bitmap file. */
+
+    /* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access.
+       Load a .png into a surface, move it to a texture from there. */
+    SDL_asprintf(&png_path, "%ssample.png", SDL_GetBasePath());  /* allocate a string of the full file path */
+    surface = SDL_LoadPNG(png_path);
+    if (!surface) {
+        SDL_Log("Couldn't load bitmap: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_free(png_path);  /* done with this, the file is loaded. */
+
+    texture_width = surface->w;
+    texture_height = surface->h;
+
+    texture = SDL_CreateTextureFromSurface(renderer, surface);
+    if (!texture) {
+        SDL_Log("Couldn't create static texture: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_DestroySurface(surface);  /* done with this, the texture has a copy of the pixels now. */
+
+    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 double now = ((double)SDL_GetTicks()) / 1000.0;  /* convert from milliseconds to seconds. */
+    /* choose the modulation values for the center texture. The sine wave trick makes it fade between colors smoothly. */
+    const float red = (float) (0.5 + 0.5 * SDL_sin(now));
+    const float green = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 2 / 3));
+    const float blue = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 4 / 3));
+
+    /* as you can see from this, rendering draws over whatever was drawn before it. */
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);  /* black, 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. */
+
+    /* Color modulation multiplies each pixel's red, green, and blue intensities by the mod values,
+       so multiplying by 1.0f will leave a color intensity alone, 0.0f will shut off that color
+       completely, etc. */
+
+    /* top left; let's make this one blue! */
+    dst_rect.x = 0.0f;
+    dst_rect.y = 0.0f;
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_SetTextureColorModFloat(texture, 0.0f, 0.0f, 1.0f);  /* kill all red and green. */
+    SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
+
+    /* center this one, and have it cycle through red/green/blue modulations. */
+    dst_rect.x = ((float) (WINDOW_WIDTH - texture_width)) / 2.0f;
+    dst_rect.y = ((float) (WINDOW_HEIGHT - texture_height)) / 2.0f;
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_SetTextureColorModFloat(texture, red, green, blue);
+    SDL_RenderTexture(renderer, texture, NULL, &dst_rect);
+
+    /* bottom right; let's make this one red! */
+    dst_rect.x = (float) (WINDOW_WIDTH - texture_width);
+    dst_rect.y = (float) (WINDOW_HEIGHT - texture_height);
+    dst_rect.w = (float) texture_width;
+    dst_rect.h = (float) texture_height;
+    SDL_SetTextureColorModFloat(texture, 1.0f, 0.0f, 0.0f);  /* kill all green and blue. */
+    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_AppResult result)
+{
+    SDL_DestroyTexture(texture);
+    /* SDL will clean up the window/renderer for us. */
+}
+