Add GlScene global VBO upload and indexed draw

CityDoctorParent/Extensions/CityDoctorGUI/src/main/java/de/hft/stuttgart/citydoctor2/gui/gl/GlScene.java

+package de.hft.stuttgart.citydoctor2.gui.gl;
+
+import com.jogamp.opengl.GL;
+import com.jogamp.opengl.GL3;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.FloatBuffer;
+import java.nio.IntBuffer;
+
+/** GPU resources for the global scene mesh. Single VBO (pos+color+id), one index buffer redrawn per frame. */
+public class GlScene {
+
+    private int vao = 0;
+    private int vboPos;
+    private int vboColor;
+    private int vboId;
+    private int ebo;
+    private int indexCount;
+    private boolean uploaded;
+
+    public void upload(GL3 gl, SceneData data) {
+        if (!uploaded) {
+            int[] ids = new int[3];
+            gl.glGenVertexArrays(1, ids, 0);
+            vao = ids[0];
+            int[] buffers = new int[4];
+            gl.glGenBuffers(4, buffers, 0);
+            vboPos = buffers[0];
+            vboColor = buffers[1];
+            vboId = buffers[2];
+            ebo = buffers[3];
+        }
+        gl.glBindVertexArray(vao);
+
+        uploadFloat(gl, vboPos, data.positions(), 0, 3);
+        uploadFloat(gl, vboColor, data.colors(), 1, 3);
+        uploadInt(gl, vboId, data.ids(), 2);
+
+        gl.glBindVertexArray(0);
+        uploaded = true;
+    }
+
+    private void uploadFloat(GL3 gl, int vbo, float[] data, int location, int components) {
+        gl.glBindBuffer(GL.GL_ARRAY_BUFFER, vbo);
+        FloatBuffer fb = toFloatBuffer(data);
+        gl.glBufferData(GL.GL_ARRAY_BUFFER, (long) data.length * Float.BYTES, fb, GL.GL_STATIC_DRAW);
+        gl.glEnableVertexAttribArray(location);
+        gl.glVertexAttribPointer(location, components, GL.GL_FLOAT, false, 0, 0L);
+    }
+
+    private void uploadInt(GL3 gl, int vbo, int[] data, int location) {
+        gl.glBindBuffer(GL.GL_ARRAY_BUFFER, vbo);
+        IntBuffer ib = toIntBuffer(data);
+        gl.glBufferData(GL.GL_ARRAY_BUFFER, (long) data.length * Integer.BYTES, ib, GL.GL_STATIC_DRAW);
+        gl.glEnableVertexAttribArray(location);
+        gl.glVertexAttribIPointer(location, 1, GL3.GL_INT, 0, 0L); // integer attribute, not normalized
+    }
+
+    /** Re-uploads which triangles to draw (element indices). Cheap; called on filter/LOD changes. */
+    public void setIndexSet(GL3 gl, int[] indices) {
+        gl.glBindVertexArray(vao);
+        gl.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, ebo);
+        IntBuffer ib = toIntBuffer(indices);
+        gl.glBufferData(GL.GL_ELEMENT_ARRAY_BUFFER, (long) indices.length * Integer.BYTES, ib,
+                GL.GL_DYNAMIC_DRAW);
+        gl.glBindVertexArray(0);
+        indexCount = indices.length;
+    }
+
+    public void draw(GL3 gl) {
+        if (vao == 0 || indexCount == 0) {
+            return;
+        }
+        gl.glBindVertexArray(vao);
+        gl.glDrawElements(GL.GL_TRIANGLES, indexCount, GL.GL_UNSIGNED_INT, 0L);
+        gl.glBindVertexArray(0);
+    }
+
+    public boolean hasData() { return uploaded; }
+
+    public void dispose(GL3 gl) {
+        if (vao != 0) {
+            gl.glDeleteVertexArrays(1, new int[]{vao}, 0);
+            gl.glDeleteBuffers(4, new int[]{vboPos, vboColor, vboId, ebo}, 0);
+            vao = 0;
+            uploaded = false;
+        }
+    }
+
+    private static FloatBuffer toFloatBuffer(float[] data) {
+        ByteBuffer bb = ByteBuffer.allocateDirect(data.length * Float.BYTES).order(ByteOrder.nativeOrder());
+        FloatBuffer fb = bb.asFloatBuffer();
+        fb.put(data).flip();
+        return fb;
+    }
+
+    private static IntBuffer toIntBuffer(int[] data) {
+        ByteBuffer bb = ByteBuffer.allocateDirect(data.length * Integer.BYTES).order(ByteOrder.nativeOrder());
+        IntBuffer ib = bb.asIntBuffer();
+        ib.put(data).flip();
+        return ib;
+    }
+}