SDL: examples/renderer/19-affine-textures: blue background so you can see the cube.

SDL Commits
1 
From 5ab1aef367004f2d4dc4a6d7d07f430be02e23d6 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Fri, 28 Mar 2025 13:55:40 -0400
Subject: [PATCH] examples/renderer/19-affine-textures: blue background so you
 can see the cube.

---
 examples/renderer/19-affine-textures/affine-textures.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/renderer/19-affine-textures/affine-textures.c b/examples/renderer/19-affine-textures/affine-textures.c
index e66938f8105a9..96a661c97a17d 100644
--- a/examples/renderer/19-affine-textures/affine-textures.c
+++ b/examples/renderer/19-affine-textures/affine-textures.c
@@ -106,7 +106,7 @@ SDL_AppResult SDL_AppIterate(void *appstate)
         corners[1 + 2*i] = mat[3]*x + mat[4]*y + mat[5]*z;
     }
 
-    SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
+    SDL_SetRenderDrawColor(renderer, 0x42, 0x87, 0xf5, SDL_ALPHA_OPAQUE);  // light blue background.
     SDL_RenderClear(renderer);
 
     for (i = 1; i < 7; i++) {