1 files changed, 78 insertions, 0 deletions
diff --git a/src/main/java/dev/figboot/cuberender/api/SkinUtil.java b/src/main/java/dev/figboot/cuberender/api/SkinUtil.java
new file mode 100644
index 0000000..5f76ebb
--- /dev/null
+++ b/src/main/java/dev/figboot/cuberender/api/SkinUtil.java
@@ -0,0 +1,78 @@
+package dev.figboot.cuberender.api;
+
+import java.awt.*;
+import java.awt.image.BufferedImage;
+
+public final class SkinUtil {
+    private SkinUtil() { }
+
+    private static void copyLimbFlipped(BufferedImage src, BufferedImage target) {
+        for (int y = 4, maxY = src.getHeight(); y < maxY; ++y) {
+            for (int x = 0; x < 4; ++x) {
+                target.setRGB(x, y, src.getRGB(11 - x, y));
+                target.setRGB(x + 4, y, src.getRGB(7 - x, y));
+                target.setRGB(x + 8, y, src.getRGB(3 - x, y));
+                target.setRGB(x + 12, y, src.getRGB(15 - x, y));
+            }
+        }
+
+        for (int y = 0; y < 4; ++y) {
+            for (int x = 0; x < 4; ++x) {
+                target.setRGB(x + 4, y, src.getRGB(7 - x, y));
+                target.setRGB(x + 8, y, src.getRGB(11 - x, y));
+            }
+        }
+    }
+
+    /**
+     * This function converts a 64x32 skin (1.8 and earlier) into a modern (64x64) skin texture.
+     * @param image the old skin
+     * @param target the new skin, or {@code null} if a new image should be created
+     * @return the new skin
+     */
+    public static BufferedImage convertToModernSkin(BufferedImage image, BufferedImage target) {
+        if (image.getWidth() != 64 || image.getHeight() != 32) {
+            throw new IllegalArgumentException("source image must be a 64x32 skin texture");
+        }
+
+        if (target == null) {
+            target = new BufferedImage(64, 64, BufferedImage.TYPE_INT_ARGB);
+        } else if (target.getWidth() != 64 || target.getHeight() != 64) {
+            throw new IllegalArgumentException("target image must be 64x64");
+        }
+
+        Graphics2D g2d = target.createGraphics();
+
+        g2d.drawImage(image, 0, 0, 64, 32, null);
+
+        copyLimbFlipped(image.getSubimage(0, 16, 16, 16), target.getSubimage(16, 48, 16, 16));
+        copyLimbFlipped(image.getSubimage(40, 16, 16, 16), target.getSubimage(32, 48, 16, 16));
+        g2d.dispose();
+
+        return target;
+    }
+
+    /**
+     * This function converts an OptiFine cape texture into a regular cape texture.
+     * @param image the OptiFine cape texture
+     * @param target the image to place the cape texture into, or {@code null} if a new image should be created
+     * @return the regular cape texture
+     */
+    public static BufferedImage convertOFToRegular(BufferedImage image, BufferedImage target) {
+        if (image.getWidth() != 46 || image.getHeight() != 22) {
+            throw new IllegalArgumentException("image must be a 46x22 OptiFine cape texture");
+        }
+
+        if (target == null) {
+            target = new BufferedImage(64, 32, BufferedImage.TYPE_INT_ARGB);
+        } else if (target.getWidth() != 64 || target.getHeight() != 32) {
+            throw new IllegalArgumentException("target image must be 64x32");
+        }
+
+        Graphics2D g2d = target.createGraphics();
+        g2d.drawImage(image, 0, 0, 46, 22, null);
+        g2d.dispose();
+
+        return target;
+    }
+}