Refine selection: no polygon tint, bigger markers, accurate picking

- Drop the selected-polygon colour tint; selection is shown only by the
  highlight points and edges (scene shader outputs vertex colour directly).
- Larger highlight points (glPointSize) and thicker edges (glLineWidth);
  markers use a constant on-screen pixel size independent of zoom.
- Fix click picking on HiDPI: scale logical click coords to physical
  framebuffer pixels so the sampled pixel is the one under the cursor.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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

@@ -61,11 +61,8 @@ public class HighlightController {
     }
 
     public void changeScaling(double translateZ) {
-        double scale = Math.abs(translateZ);
-        scale = Math.min(150, scale);
-        scale = Math.max(10, scale);
-        scale = scale * 0.01;
-        viewport.setPointScale((float) (scale * 8));
+        // GL points/lines are sized in screen pixels, so highlight markers keep a constant on-screen
+        // size regardless of zoom distance; nothing to recompute here.
     }
 
     // ---- point/line accumulation ----

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

@@ -33,10 +33,10 @@ public class GLViewport {
     // last index set seen; retained so it can be (re)applied after the scene is uploaded or the GL
     // context is recreated (the index buffer only exists once the scene's buffers have been generated)
     private volatile int[] lastIndices;
-    private volatile int selectedId = 0;
     private volatile boolean wireframe = false;
     private volatile boolean cull = false;
-    private volatile float pointScale = 5f;
+    private volatile float pointScale = 14f;
+    private volatile float lineScale = 4f;
 
     // highlight marker data, uploaded on the GL thread when dirty
     private volatile float[] hlPoints = new float[0];
@@ -45,8 +45,8 @@ public class GLViewport {
     private volatile float[] hlLineColors = new float[0];
     private volatile boolean highlightsDirty = false;
 
-    // pick request: screen coords + callback (invoked on FX thread with resolved Object or null)
-    private volatile int[] pickRequest;
+    // pick request: logical (JavaFX) screen coords + callback (invoked on FX thread with resolved Object)
+    private volatile double[] pickRequest;
     private volatile Consumer<Object> pickCallback;
     private SceneData currentScene;
 
@@ -78,8 +78,6 @@ public class GLViewport {
 
     public void setIndexSet(int[] indices) { pendingIndexSet.set(indices); canvas.repaint(); }
 
-    public void setSelectedId(int id) { selectedId = id; canvas.repaint(); }
-
     public void setWireframe(boolean on) { wireframe = on; canvas.repaint(); }
 
     public void setCulling(boolean on) { cull = on; canvas.repaint(); }
@@ -99,7 +97,7 @@ public class GLViewport {
     public OrbitCamera camera() { return camera; }
 
     public void requestPick(double x, double y, Consumer<Object> callback) {
-        pickRequest = new int[]{(int) Math.round(x), (int) Math.round(y)};
+        pickRequest = new double[]{x, y};
         pickCallback = callback;
         canvas.repaint();
     }
@@ -159,11 +157,10 @@ public class GLViewport {
 
         sceneProgram.use(gl);
         gl.glUniformMatrix4fv(sceneProgram.uniform(gl, "uMVP"), 1, false, mvp, 0);
-        gl.glUniform1i(sceneProgram.uniform(gl, "uSelectedId"), selectedId);
         scene.draw(gl);
-        overlay.draw(gl, pointScale);
+        overlay.draw(gl, pointScale, lineScale);
 
-        int[] req = pickRequest;
+        double[] req = pickRequest;
         if (req != null && currentScene != null) {
             picking.resize(gl, w, h);
             picking.bind(gl);
@@ -173,9 +170,16 @@ public class GLViewport {
             pickProgram.use(gl);
             gl.glUniformMatrix4fv(pickProgram.uniform(gl, "uMVP"), 1, false, mvp, 0);
             scene.draw(gl);
-            int id = picking.readId(gl, req[0], req[1]);
+            // click coords are logical (JavaFX) px; the picking buffer is physical px. Scale by the
+            // framebuffer/canvas ratio so HiDPI displays read the pixel actually under the cursor.
+            double cw = canvas.getWidth();
+            double ch = canvas.getHeight();
+            float sx = cw > 0 ? (float) (w / cw) : 1f;
+            float sy = ch > 0 ? (float) (h / ch) : 1f;
+            int px = Math.round((float) req[0] * sx);
+            int py = Math.round((float) req[1] * sy);
+            int id = picking.readId(gl, px, py);
             Object target = currentScene.pickRegistry().resolve(id);
-            selectedId = (target != null) ? id : 0;
             Consumer<Object> cb = pickCallback;
             pickRequest = null;
             pickCallback = null;

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

@@ -74,11 +74,12 @@ public class HighlightOverlay {
         gl.glVertexAttribPointer(loc, comp, GL.GL_FLOAT, false, 0, 0L);
     }
 
-    public void draw(GL3 gl, float pointSize) {
+    public void draw(GL3 gl, float pointSize, float lineWidth) {
         if (!created) {
             return;
         }
         if (lineVertexCount > 0) {
+            gl.glLineWidth(lineWidth);
             gl.glBindVertexArray(lineVao);
             gl.glDrawArrays(GL.GL_LINES, 0, lineVertexCount);
         }

CityDoctorParent/Extensions/CityDoctorGUI/src/main/resources/de/hft/stuttgart/citydoctor2/gui/gl/scene.frag

 #version 330 core
 in vec3 vColor;
-flat in int vSelected;
 out vec4 fragColor;
 void main() {
-    vec3 c = vColor;
-    if (vSelected == 1) {
-        c = mix(c, vec3(1.0, 0.0, 0.0), 0.6);
-    }
-    fragColor = vec4(c, 1.0);
+    fragColor = vec4(vColor, 1.0);
 }

CityDoctorParent/Extensions/CityDoctorGUI/src/main/resources/de/hft/stuttgart/citydoctor2/gui/gl/scene.vert

 #version 330 core
 layout(location = 0) in vec3 aPos;
 layout(location = 1) in vec3 aColor;
-layout(location = 2) in int  aId;
 uniform mat4 uMVP;
-uniform int  uSelectedId;
 out vec3 vColor;
-flat out int vSelected;
 void main() {
     gl_Position = uMVP * vec4(aPos, 1.0);
     vColor = aColor;
-    vSelected = (aId == uSelectedId) ? 1 : 0;
 }