From 9d0b3eded610ccc15f414ecf91fe8b3bfac4801d Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Fri, 20 Sep 2024 22:31:37 -0400
Subject: [PATCH] examples: added renderer/05-rectangles
---
examples/CMakeLists.txt | 1 +
examples/renderer/05-rectangles/README.txt | 3 +
.../05-rectangles/renderer-rectangles.c | 110 ++++++++++++++++++
3 files changed, 114 insertions(+)
create mode 100644 examples/renderer/05-rectangles/README.txt
create mode 100644 examples/renderer/05-rectangles/renderer-rectangles.c
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index fb4db69fa2a3f..10ccb05dac119 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -124,6 +124,7 @@ add_sdl_example_executable(renderer-clear SOURCES renderer/01-clear/renderer-cle
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(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(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/05-rectangles/README.txt b/examples/renderer/05-rectangles/README.txt
new file mode 100644
index 0000000000000..26613c706ea6e
--- /dev/null
+++ b/examples/renderer/05-rectangles/README.txt
@@ -0,0 +1,3 @@
+This example creates an SDL window and renderer, and then draws a few
+rectangles that change size each frame.
+
diff --git a/examples/renderer/05-rectangles/renderer-rectangles.c b/examples/renderer/05-rectangles/renderer-rectangles.c
new file mode 100644
index 0000000000000..2fd2ba8074f7b
--- /dev/null
+++ b/examples/renderer/05-rectangles/renderer-rectangles.c
@@ -0,0 +1,110 @@
+/*
+ * This example creates an SDL window and renderer, and then draws some
+ * rectangles 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;
+
+#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/rectangles", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) {
+ SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", 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 rects[16];
+ const Uint64 now = SDL_GetTicks();
+ int i;
+
+ /* we'll have the rectangles grow and shrink 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;
+
+ /* 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. */
+
+ /* Rectangles are comprised of set of X and Y coordinates, plus width and
+ height. (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. */
+
+ /* Let's draw a single rectangle (square, really). */
+ rects[0].x = rects[0].y = 100;
+ rects[0].w = rects[0].h = 100 + (100 * scale);
+ SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255); /* red, full alpha */
+ SDL_RenderRect(renderer, &rects[0]);
+
+ /* Now let's draw several rectangles with one function call. */
+ for (i = 0; i < 3; i++) {
+ const float size = (i+1) * 50.0f;
+ rects[i].w = rects[i].h = size + (size * scale);
+ rects[i].x = (WINDOW_WIDTH - rects[i].w) / 2; /* center it. */
+ rects[i].y = (WINDOW_HEIGHT - rects[i].h) / 2; /* center it. */
+ }
+ SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); /* green, full alpha */
+ SDL_RenderRects(renderer, rects, 3); /* draw three rectangles at once */
+
+ /* those were rectangle _outlines_, really. You can also draw _filled_ rectangles! */
+ rects[0].x = 400;
+ rects[0].y = 50;
+ rects[0].w = 100 + (100 * scale);
+ rects[0].h = 50 + (50 * scale);
+ SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255); /* blue, full alpha */
+ SDL_RenderFillRect(renderer, &rects[0]);
+
+ /* ...and also fill a bunch of rectangles at once... */
+ for (i = 0; i < SDL_arraysize(rects); i++) {
+ const float w = (float) (WINDOW_WIDTH / SDL_arraysize(rects));
+ const float h = i * 8.0f;
+ rects[i].x = i * w;
+ rects[i].y = WINDOW_HEIGHT - h;
+ rects[i].w = w;
+ rects[i].h = h;
+ }
+ SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); /* white, full alpha */
+ SDL_RenderFillRects(renderer, rects, SDL_arraysize(rects));
+
+ 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. */
+}
+