From d521c06c34a7b73a6a45de8bebac83cac843581c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakob=20H=C3=B6rdt?=
 <6329417-neop_@users.noreply.gitlab.com>
Date: Sat, 3 Aug 2024 23:38:19 +0200
Subject: [PATCH] simple surface drawing

---
 main.cpp | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/main.cpp b/main.cpp
index 6804914..b6285a1 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,13 +2,9 @@
 
 #include <SDL2/SDL.h>
 
-#include <algorithm>
-#include <chrono>
-#include <functional>
 #include <memory>
 #include <print>
 #include <random>
-#include <vector>
 
 template <typename SDLT, auto deletef>
 struct sdl_wrapper_t : std::unique_ptr<SDLT, decltype(deletef)> {
@@ -73,6 +69,13 @@ int main() {
 	auto* window_surface = SDL_GetWindowSurface(window);
 	if (!window_surface) { return EXIT_FAILURE; }
 	if (window_surface->format->palette) { return EXIT_FAILURE; }
+	std::println(
+		"got surface with {} bits per pixel",
+		window_surface->format->BitsPerPixel
+	);
+	if (!(window_surface->format->format & SDL_PIXELFORMAT_RGBA32)) {
+		return EXIT_FAILURE;
+	}
 
 	SDL_Point pos{.x = width / 2, .y = height / 2};
 	const SDL_Point directions[] = {
@@ -81,17 +84,20 @@ int main() {
 
 	std::mt19937_64 rne(std::random_device{}());
 	std::uniform_int_distribution dist(0, 3);
+	//                              aarrggbb??
+	constexpr Uint32 walk_color = 0xff00ff00;
 
 	for (bool continu = true; continu;) {
-
-		{
-			SDL_Point newpoint;
-			do {
-				newpoint = pos + directions[dist(rne)];
-			} while (newpoint.x < 0 or newpoint.x >= width or newpoint.y < 0 or
-			         newpoint.y >= height);
-			pos = newpoint;
-		}
+		SDL_Point newpoint;
+		do {
+			newpoint = pos + directions[dist(rne)];
+		} while (newpoint.x < 0 or newpoint.x >= width or newpoint.y < 0 or
+		         newpoint.y >= height);
+		pos = newpoint;
+		SDL_LockSurface(window_surface);
+		static_cast<Uint32*>(window_surface->pixels
+		)[pos.x + pos.y * window_surface->h] = walk_color;
+		SDL_UnlockSurface(window_surface);
 
 		for (SDL_Event e; SDL_PollEvent(&e);) {
 			if (e.type == SDL_QUIT) { continu = false; }