chore: add test cases for IndexResource and address some problems found through test cases

engine-tests/src/test/java/org/terasology/engine/rendering/assets/mesh/IndexResourceTest.java

@@ -0,0 +1,87 @@
+// Copyright 2021 The Terasology Foundation
+// SPDX-License-Identifier: Apache-2.0
+
+package org.terasology.engine.rendering.assets.mesh;
+
+import org.junit.jupiter.api.Test;
+import org.terasology.engine.rendering.assets.mesh.resource.IndexResource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class IndexResourceTest {
+    @Test
+    public void testPutIndexResource() {
+        IndexResource in = new IndexResource();
+        in.put(10);
+        in.put(11);
+        in.put(15);
+
+        assertEquals(3, in.indices());
+        in.writeBuffer(buffer -> {
+            assertEquals(3 * Integer.BYTES, buffer.limit());
+
+            assertEquals(10, buffer.getInt(0));
+            assertEquals(11, buffer.getInt(1 * Integer.BYTES));
+            assertEquals(15, buffer.getInt(2 * Integer.BYTES));
+        });
+    }
+
+    @Test
+    public void testRewind() {
+        IndexResource in = new IndexResource();
+        in.put(10);
+        in.put(11);
+        in.put(15);
+
+        assertEquals(3, in.indices());
+        in.writeBuffer(buffer -> {
+            assertEquals(3 * Integer.BYTES, buffer.limit());
+
+            assertEquals(10, buffer.getInt(0));
+            assertEquals(11, buffer.getInt(1 * Integer.BYTES));
+            assertEquals(15, buffer.getInt(2 * Integer.BYTES));
+        });
+
+        in.rewind();
+        in.put(20);
+        assertEquals(3, in.indices());
+        in.writeBuffer(buffer -> {
+            assertEquals(3 * Integer.BYTES, buffer.limit());
+
+            assertEquals(20, buffer.getInt(0));
+            assertEquals(11, buffer.getInt(1 * Integer.BYTES));
+            assertEquals(15, buffer.getInt(2 * Integer.BYTES));
+        });
+
+    }
+
+    @Test
+    public void testAllocate() {
+
+        IndexResource in = new IndexResource();
+        in.allocateElements(20); // re-allocate to 20 indices
+
+        in.put(100);
+        in.put(14);
+        in.put(10);
+
+        assertEquals(20, in.indices());
+        in.writeBuffer(buffer -> {
+            assertEquals(20 * Integer.BYTES, buffer.limit());
+
+            assertEquals(100, buffer.getInt(0));
+            assertEquals(14, buffer.getInt(1 * Integer.BYTES));
+            assertEquals(10, buffer.getInt(2 * Integer.BYTES));
+        });
+
+        in.allocateElements(4); // re-allocate to 4 indices
+        assertEquals(4, in.indices());
+        in.writeBuffer(buffer -> {
+            assertEquals(4 * Integer.BYTES, buffer.limit());
+
+            assertEquals(100, buffer.getInt(0));
+            assertEquals(14, buffer.getInt(1 * Integer.BYTES));
+            assertEquals(10, buffer.getInt(2 * Integer.BYTES));
+        });
+    }
+}

engine/src/main/java/org/terasology/engine/rendering/assets/mesh/resource/IndexResource.java

@@ -13,21 +13,19 @@
  */
 public class IndexResource extends BufferedResource {
     public static final Logger logger = LoggerFactory.getLogger(IndexResource.class);
-    private int inIndices = 0;
     private int posIndex = 0;
 
     public IndexResource() {
         super();
     }
 
     public int indices() {
-        return inIndices;
+        return this.inSize / Integer.BYTES;
     }
 
     public void copy(IndexResource resource) {
         copyBuffer(resource);
         this.inSize = resource.inSize;
-        this.inIndices = resource.indices();
     }
 
     public void reserveElements(int elements) {
@@ -36,16 +34,12 @@ public void reserveElements(int elements) {
 
     public void rewind() {
         posIndex = 0;
-        inIndices = 0;
     }
 
     public void put(int value) {
         ensureCapacity((posIndex + 1) * Integer.BYTES);
         buffer.putInt(posIndex * Integer.BYTES, value);
         posIndex++;
-        if (posIndex > inIndices) {
-            inIndices = posIndex;
-        }
     }
 
     public void putAll(int value, int... values) {
@@ -77,10 +71,6 @@ public void put(int index, int value) {
 
     @Override
     public boolean isEmpty() {
-        return inIndices == 0;
+        return this.inSize == 0;
     }
-
-
-
-
 }

engine/src/main/java/org/terasology/engine/rendering/opengl/OpenGLMesh.java

@@ -31,7 +31,7 @@ public class OpenGLMesh extends Mesh implements OpenGLMeshBase {
     private DrawingMode drawMode;
     private AllocationType allocationType;
 
-    private  VertexAttributeBinding<Vector3fc, Vector3f> positions;
+    private VertexAttributeBinding<Vector3fc, Vector3f> positions;
 
     private VBOContext state = null;
 
@@ -79,7 +79,7 @@ public void render() {
         if (!isDisposed()) {
             updateState(state);
             GL30.glBindVertexArray(disposalAction.vao);
-            if(this.indexCount == 0) {
+            if (this.indexCount == 0) {
                 GL30.glDrawArrays(drawMode.glCall, 0, positions.elements());
             } else {
                 GL30.glDrawElements(drawMode.glCall, this.indexCount, GL_UNSIGNED_INT, 0);