examples: added renderer/03-lines

examples/CMakeLists.txt

@@ -122,6 +122,7 @@ endmacro()
 
 add_sdl_example_executable(renderer-clear SOURCES renderer/01-clear/renderer-clear.c)
 add_sdl_example_executable(renderer-primitives SOURCES renderer/02-primitives/renderer-primitives.c)
+add_sdl_example_executable(renderer-lines SOURCES renderer/03-lines/renderer-lines.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)

examples/renderer/03-lines/README.txt

@@ -0,0 +1,3 @@
+This example creates an SDL window and renderer, and then draws a giant
+pile of lines, in random colors, every frame.
+

examples/renderer/03-lines/renderer-lines.c

@@ -0,0 +1,68 @@
+/*
+ * This example creates an SDL window and renderer, and then draws some lines,
+ * rectangles and points 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[])
+{
+    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/lines", 640, 480, 0, &window, &renderer)) {
+        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", SDL_GetError(), NULL);
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_srand(0);  /* seed the random number generator */
+
+    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)
+{
+    const int num_lines = 5000;
+    int i;
+
+    /* as you can see from this, rendering draws over whatever was drawn before it. */
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);  /* black, full alpha */
+    SDL_RenderClear(renderer);  /* start with a blank canvas. */
+
+    for (i = 0; i < num_lines; i++) {
+        SDL_SetRenderDrawColor(renderer, SDL_rand(256), SDL_rand(256), SDL_rand(256), 255);
+        SDL_RenderLine(renderer, SDL_rand(640), SDL_rand(480), SDL_rand(640), SDL_rand(480));
+    }
+
+    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. */
+}
+