chore(build): use SDL3

vendor/sdl-3.2.10/examples/renderer/03-lines/README.txt

@@ -0,0 +1,3 @@
+This example creates an SDL window and renderer, and then draws a something
+roughly like a Christmas tree with nothing but lines, every frame.
+

vendor/sdl-3.2.10/examples/renderer/03-lines/lines.c

@@ -0,0 +1,93 @@
+/*
+ * This example creates an SDL window and renderer, and then draws some lines
+ * 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 <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;
+
+/* This function runs once at startup. */
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+    SDL_SetAppMetadata("Example Renderer Lines", "1.0", "com.example.renderer-lines");
+
+    if (!SDL_Init(SDL_INIT_VIDEO)) {
+        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    if (!SDL_CreateWindowAndRenderer("examples/renderer/lines", 640, 480, 0, &window, &renderer)) {
+        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
+        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)
+{
+    int i;
+
+    /* Lines (line segments, really) are drawn in terms of points: a set of
+       X and Y coordinates, one set for each end of the line.
+       (0, 0) is the top left of the window, and larger numbers go down
+       and to the right. This isn't how geometry works, but this is pretty
+       standard in 2D graphics. */
+    static const SDL_FPoint line_points[] = {
+        { 100, 354 }, { 220, 230 }, { 140, 230 }, { 320, 100 }, { 500, 230 },
+        { 420, 230 }, { 540, 354 }, { 400, 354 }, { 100, 354 }
+    };
+
+    /* as you can see from this, rendering draws over whatever was drawn before it. */
+    SDL_SetRenderDrawColor(renderer, 100, 100, 100, SDL_ALPHA_OPAQUE);  /* grey, full alpha */
+    SDL_RenderClear(renderer);  /* start with a blank canvas. */
+
+    /* You can draw lines, one at a time, like these brown ones... */
+    SDL_SetRenderDrawColor(renderer, 127, 49, 32, SDL_ALPHA_OPAQUE);
+    SDL_RenderLine(renderer, 240, 450, 400, 450);
+    SDL_RenderLine(renderer, 240, 356, 400, 356);
+    SDL_RenderLine(renderer, 240, 356, 240, 450);
+    SDL_RenderLine(renderer, 400, 356, 400, 450);
+
+    /* You can also draw a series of connected lines in a single batch... */
+    SDL_SetRenderDrawColor(renderer, 0, 255, 0, SDL_ALPHA_OPAQUE);
+    SDL_RenderLines(renderer, line_points, SDL_arraysize(line_points));
+
+    /* here's a bunch of lines drawn out from a center point in a circle. */
+    /* we randomize the color of each line, so it functions as animation. */
+    for (i = 0; i < 360; i++) {
+        const float size = 30.0f;
+        const float x = 320.0f;
+        const float y = 95.0f - (size / 2.0f);
+        SDL_SetRenderDrawColor(renderer, SDL_rand(256), SDL_rand(256), SDL_rand(256), SDL_ALPHA_OPAQUE);
+        SDL_RenderLine(renderer, x, y, x + SDL_sinf((float) i) * size, y + SDL_cosf((float) i) * size);
+    }
+
+    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 will clean up the window/renderer for us. */
+}
+