examples: Add example of using affine sprites

examples/graphics/spriteaffine/Makefile

@@ -0,0 +1 @@
+include ../../Makefile.example

examples/graphics/spriteaffine/assets/convert.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+BLOCKSDS="${BLOCKSDS:-/opt/blocksds/core/}"
+GRIT=$BLOCKSDS/tools/grit/grit
+
+$GRIT ball.png -ftB -fh! -gTFF00FF -gt -gB8 -m!
+
+mv *.pal *.img ../nitrofiles/sprite

examples/graphics/spriteaffine/source/main.c

@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: CC0-1.0
+//
+// SPDX-FileContributor: NightFox & Co., 2009-2011
+// SPDX-FileContributor: Antonio Niño Díaz, 2025
+//
+// Affine sprite loading example
+// http://www.nightfoxandco.com
+
+#include <stdio.h>
+#include <time.h>
+
+#include <nds.h>
+#include <filesystem.h>
+
+#include <nf_lib.h>
+
+int main(int argc, char **argv)
+{
+    // Set random seed based on the current time
+    srand(time(NULL));
+
+    // Prepare a NitroFS initialization screen
+    NF_Set2D(0, 0);
+    NF_Set2D(1, 0);
+    consoleDemoInit();
+    printf("\n NitroFS init. Please wait.\n\n");
+    printf(" Iniciando NitroFS,\n por favor, espere.\n\n");
+    swiWaitForVBlank();
+
+    // Initialize NitroFS and set it as the root folder of the filesystem
+    nitroFSInit(NULL);
+    NF_SetRootFolder("NITROFS");
+
+    // Initialize 2D engine in both screens and use mode 0
+    NF_Set2D(0, 0);
+    NF_Set2D(1, 0);
+
+    // Initialize sprite system
+    NF_InitSpriteBuffers();     // Initialize storage buffers
+    NF_InitSpriteSys(0);        // Top screen
+    NF_InitSpriteSys(1);        // Bottom screen
+
+    NF_LoadSpriteGfx("sprite/ball", 0, 32, 32);
+    NF_LoadSpritePal("sprite/ball", 0);
+
+    // Transfer the required sprites to VRAM
+    NF_VramSpriteGfx(1, 0, 0, true);
+    NF_VramSpritePal(1, 0, 0);
+
+    // Setup ball sprites
+    NF_CreateSprite(1, 10, 0, 0, 16, 16);
+    NF_EnableSpriteRotScale(1, 10, 4, false); // rotation ID 4, no double size
+
+    NF_CreateSprite(1, 20, 0, 0, 128, 16);
+    NF_EnableSpriteRotScale(1, 20, 4, true); // rotation ID 4, double size
+
+    NF_CreateSprite(1, 30, 0, 0, 16, 96);
+    NF_EnableSpriteRotScale(1, 30, 5, false); // rotation ID 5, no double size
+
+    NF_CreateSprite(1, 40, 0, 0, 128, 96);
+    NF_EnableSpriteRotScale(1, 40, 5, true); // rotation ID 5, double size
+
+    int angle = 512;
+    int scale = 350;
+
+    while (1)
+    {
+        scanKeys(); // Read keypad
+        u16 keys = keysHeld(); // Keys currently pressed
+
+        // Rotate and scale sprites
+
+        if (keys & KEY_LEFT)
+            angle += 16;
+        if (keys & KEY_RIGHT)
+            angle -= 16;
+
+        angle &= 511;
+
+        if (keys & KEY_A)
+        {
+            scale += 2;
+            if (scale > 512)
+                scale = 512;
+        }
+        if (keys & KEY_B)
+        {
+            scale -= 2;
+            if (scale < 0)
+                scale = 0;
+        }
+
+        NF_SpriteRotScale(1, 4, angle, scale, scale);
+        NF_SpriteRotScale(1, 5, -angle, scale, scale);
+
+        // Update OAM array
+        NF_SpriteOamSet(0);
+        NF_SpriteOamSet(1);
+
+        // Wait for the screen refresh
+        swiWaitForVBlank();
+
+        // Update OAM
+        oamUpdate(&oamMain);
+        oamUpdate(&oamSub);
+    }
+
+    return 0;
+}