Differences

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--- interaction [2020/05/26 12:41] – [Interaction] admin
+++ interaction [2020/05/26 12:53] – [Gesture Interaction] admin
@@ Line 210: / Line 210: @@
 ===== Gesture Interaction =====
+Gesture handling is supported for Gorilla3D viewport. To allow gesture management you will need a TGestureManager component on your form and you have to link it to the TGorillaViewport component.
+In the example below it is described, how to rotate and zoom a model. Therefor we use the interactive gestures: ZOOM and PAN.
+In the //OnGesture// event of our GorillaViewport1 we setup a callback procedure to handle gesture input. Simple check for the supplied interactive gesture event: //igiZoom// or //igiPan// and execute the very simple //DoZoom// and //DoRotate// sub-routines.
+<file pascal>
+type
+  TForm1 = class(TForm)
+    GorillaViewport1: TGorillaViewport;
+    GestureManager1: TGestureManager;
+    GorillaModel1: TGorillaModel;
+    procedure GorillaViewport1Gesture(Sender: TObject;
+      const EventInfo: TGestureEventInfo; var Handled: Boolean);
+    protected
+      FLastPos : TPointF;
+    [...]
+  end;
+procedure TForm1.FormCreate(Sender : TObject);
+begin
+  GorillaViewport1.Touch.GestureManager := GestureManager1;
+  GorillaViewport1.Touch.InteractiveGestures := [Zoom, Pan];
+  GorillaViewport1.OnGesture := GorillaViewport1Gesture;
+  [...]
+end;
+procedure TForm1.GorillaViewport1Gesture(Sender: TObject;
+  const EventInfo: TGestureEventInfo; var Handled: Boolean);
+  procedure DoZoom();
+  var LScale : Single;
+  begin
+    if not (TInteractiveGestureFlag.gfBegin in EventInfo.Flags)
+    and not (TInteractiveGestureFlag.gfEnd in EventInfo.Flags) then
+    begin
+      LScale := EventInfo.Distance / 100;
+      GorillaModel1.Scale.Point := Point3D(LScale, LScale, LScale);
+    end;
+  end;
+  procedure DoRotate();
+  var LDist : Single;
+      LDiff,
+      LNew,
+      LPos  : TPointF;
+  begin
+    LNew := EventInfo.Location;
+    if not Assigned(GorillaModel1) then
+    begin
+      FLastPos := LNew;
+      Exit;
+    end;
+    if not (TInteractiveGestureFlag.gfBegin in EventInfo.Flags)
+    and not (TInteractiveGestureFlag.gfEnd in EventInfo.Flags) then
+    begin
+      LPos := EventInfo.Location;
+      LDiff := FLastPos - LPos;
+      LDist := LDiff.X / 5;
+      GorillaModel1.RotationAngle.Y := GorillaModel1.RotationAngle.Y + LDist;
+    end;
+    FLastPos := LNew;
+  end;
+begin
+  // just a dirty and quick solution for gesture handling
+  case EventInfo.GestureID of
+    igiZoom :
+      begin
+        // zoom
+        DoZoom();
+        Handled := true;
+      end;
+    igiPan :
+      begin
+        // rotate model
+        DoRotate();
+        Handled := true;
+      end;
+    else
+      begin
+        Handled := false;
+      end;
+  end;
+end;
+</file>
 ===== GamePad Interaction =====