Use MethodHandles to select LWJGL 3.3 methods if needed

src/main/java/org/embeddedt/modernfix/textures/StbStitcher.java

@@ -11,12 +11,119 @@ import org.lwjgl.stb.STBRPNode;
 import org.lwjgl.stb.STBRPRect;
 import org.lwjgl.stb.STBRectPack;
 
+import static java.lang.invoke.MethodHandles.*;
+import static java.lang.invoke.MethodType.*;
+
+import java.lang.invoke.MethodHandle;
+import java.sql.Ref;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Stream;
 
 /* Source: https://github.com/GTNewHorizons/lwjgl3ify/blob/f21364cd3d178aef863458a2faa1f5718a4e350d/src/main/java/me/eigenraven/lwjgl3ify/textures/StbStitcher.java */
 public class StbStitcher {
+    /* Most of this logic is to allow use of LWJGL versions where coordinates are short and versions where they are int */
+    private static final MethodHandle MH_rect_shortSet, MH_rect_intSet, MH_rect_intX, MH_rect_intY, MH_rect_shortX,
+        MH_rect_shortY;
+
+    static {
+        MethodHandle shortM = null, intM = null;
+        List<ReflectiveOperationException> exceptions = new ArrayList<>();
+        try {
+            intM = publicLookup().findVirtual(STBRPRect.class, "set", methodType(STBRPRect.class,
+                    int.class, /* id */
+                    int.class,
+                    int.class,
+                    int.class,
+                    int.class,
+                    boolean.class));
+        } catch(ReflectiveOperationException e) {
+            exceptions.add(e);
+        }
+        try {
+            shortM = publicLookup().findVirtual(STBRPRect.class, "set", methodType(STBRPRect.class,
+                    int.class, /* id */
+                    short.class,
+                    short.class,
+                    short.class,
+                    short.class,
+                    boolean.class));
+        } catch(ReflectiveOperationException e) {
+            exceptions.add(e);
+        }
+        if(shortM == null && intM == null) {
+            IllegalStateException e = new IllegalStateException("An STBRPRect set method could not be located");
+            exceptions.forEach(e::addSuppressed);
+            throw e;
+        }
+        MH_rect_shortSet = shortM;
+        MH_rect_intSet = intM;
+        /* Now look for X methods */
+        exceptions.clear();
+        try {
+            intM = publicLookup().findVirtual(STBRPRect.class, "x", methodType(int.class));
+        } catch(ReflectiveOperationException e) {
+            exceptions.add(e);
+        }
+        try {
+            shortM = publicLookup().findVirtual(STBRPRect.class, "x", methodType(short.class));
+        } catch(ReflectiveOperationException e) {
+            exceptions.add(e);
+        }
+        if(shortM == null && intM == null) {
+            IllegalStateException e = new IllegalStateException("An STBRPRect x() method could not be located");
+            exceptions.forEach(e::addSuppressed);
+            throw e;
+        }
+        MH_rect_shortX = shortM;
+        MH_rect_intX = intM;
+        /* Assume that Y is the same */
+        try {
+            if(MH_rect_shortX != null) {
+                MH_rect_shortY = publicLookup().findVirtual(STBRPRect.class, "y", methodType(short.class));
+                MH_rect_intY = null;
+            } else { /* it must be int */
+                MH_rect_intY = publicLookup().findVirtual(STBRPRect.class, "y", methodType(int.class));
+                MH_rect_shortY = null;
+            }
+        } catch(ReflectiveOperationException e) {
+            throw new IllegalStateException("An STBRPRect y() method could not be located", e);
+        }
+    }
+
+    private static STBRPRect setWrapper(STBRPRect rect, int id, int width, int height, int x, int y, boolean was_packed) {
+        try {
+            if(MH_rect_shortSet != null)
+                return (STBRPRect)MH_rect_shortSet.invokeExact(rect, id, (short)width, (short)height, (short)0, (short)0, false);
+            else
+                return (STBRPRect)MH_rect_intSet.invokeExact(rect, id, width, height, 0, 0, false);
+        } catch(Throwable e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    private static int getX(STBRPRect rect) {
+        try {
+            if(MH_rect_shortX != null)
+                return (short)MH_rect_shortX.invokeExact(rect);
+            else
+                return (int)MH_rect_intX.invokeExact(rect);
+        } catch(Throwable e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    private static int getY(STBRPRect rect) {
+        try {
+            if(MH_rect_shortX != null)
+                return (short)MH_rect_shortY.invokeExact(rect);
+            else
+                return (int)MH_rect_intY.invokeExact(rect);
+        } catch(Throwable e) {
+            throw new AssertionError(e);
+        }
+    }
+
     public static Pair<Pair<Integer, Integer>, List<LoadableSpriteInfo>> packRects(Stitcher.Holder[] holders) {
         int holderSize = holders.length;
 
@@ -36,7 +143,9 @@ public class StbStitcher {
                 int height = holder.height;
 
                 // The ID here is just the array index, for easy lookup later
-                rectBuf.get(j).set(j, (short)width, (short)height, (short)0, (short)0, false);
+                STBRPRect rect = rectBuf.get(j);
+
+                setWrapper(rect, j, width, height, 0, 0, false);
 
                 sqSize += (width * height);
             }
@@ -63,7 +172,7 @@ public class StbStitcher {
                     }
 
                     // Initialize the sprite now with the position and size that we've calculated so far
-                    infoList.add(new LoadableSpriteInfo(holder.spriteInfo, width, height, rect.x(), rect.y()));
+                    infoList.add(new LoadableSpriteInfo(holder.spriteInfo, width, height, getX(rect), getY(rect)));
                     //holder.spriteInfo.initSprite(size, size, rect.x(), rect.y(), false);
                 }