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--- interaction [2020/05/26 12:52] – [Gesture Interaction] admin
+++ interaction [Unknown date] (current) – removed - external edit (Unknown date) 127.0.0.1
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-====== Interaction ======
-In the following the implementation of mouse, keyboard and gesture interaction with default FMX methods will be described.
-In case you'll need extended features, have a look at the InputController implementation: [[inputpolling|Input Polling]]
-===== Mouse Interaction =====
-Default FMX event handling may be confusing for some of you, by a bit misleading and unexpected behaviour.
-Especially the way when events getting called and which components receive those events.
-At first you should decide which kind of mouse event handling you expect.
-==== In Viewport ====
-In case you want an overall mouse interaction over the complete scene in your viewport, like a rotation of camera around the scene center. This may be the behaviour you like.
-The following code snippet shows how to rotate camera around the center, when left mouse button is down. A special scene setup is important. The GorillaCamera1 is attached as child of Dummy1 with an offset (Position.Z = -10). Also the GorillaCamera1.Target is set to Dummy1.
-This means the camera is always focusing the dummy object.
-<file pascal>
-type
-  TForm1 = class(TForm)
-    GorillaViewport1: TGorillaViewport;
-    Dummy1: TDummy;
-    GorillaCamera1: TGorillaCamera;
-  private
-    FIsMoving : Boolean;
-    FLastPoint : TPointF;
-    procedure DoOnViewportMouseUp(ASender : TObject; AButton : TMouseButton;
-      AShift : TShiftState; X, Y : Single);
-    procedure DoOnViewportMouseDown(ASender : TObject; AButton : TMouseButton;
-      AShift : TShiftState; X, Y : Single);
-    procedure DoOnViewportMouseMove(ASender : TObject; AShiftState : TShiftState;
-      X, Y : Single);
-  end;
-  [...]
-procedure TForm1.FormCreate(Sender: TObject);
-begin
-  GorillaViewport1.OnMouseUp   := DoOnViewportMouseUp;
-  GorillaViewport1.OnMouseDown := DoOnViewportMouseDown;
-  GorillaViewport1.OnMouseMove := DoOnViewportMouseMove;
-  [...]
-end;
-procedure TForm1.DoOnViewportMouseUp(ASender : TObject; AButton : TMouseButton;
-  AShift : TShiftState; X, Y : Single);
-begin
-  FIsMoving := false;
-end;
-procedure TForm1.DoOnViewportMouseDown(ASender : TObject; AButton : TMouseButton;
-  AShift : TShiftState; X, Y : Single);
-begin
-  FIsMoving  := true;
-  FLastPoint := PointF(X, Y);
-end;
-procedure TForm1.DoOnViewportMouseMove(ASender : TObject; AShiftState : TShiftState;
-  X, Y : Single);
-var LDiff : TPointF;
-begin
-  if FIsMoving then
-  begin
-    if (ssLeft in AShiftState) then
-    begin
-      LDiff := PointF(X, Y) - FLastPoint;
-      Dummy1.RotationAngle.Y := Dummy1.RotationAngle.Y + LDiff.X;
-    end;
-    FLastPoint := PointF(X, Y);
-  end;
-end;
-</file>
-A mouse event checks all controls on your form to see if the mouse position is within one of these elements.
-So in case you have, for example a cube in your scene and the mouse hovers over this cube, FMX will call the MouseMove event of the cube, instead of the viewport.
-So they above defined events will not be thrown and rotation will not be executed.
-To make your mouse move events available all over the viewport, you have to set HitTest of each object inside of the viewport to FALSE.
-Another solution is to include rotation behaviour in each object related mouse-move event, or to use TGorillaInputController with global mouse hooks ([[inputpolling|Input Polling]]).
-==== On components ====
-Like described above, it sometimes is necessary to detect mouse events on components itself.
-For TControl3D instances like a TGorillaCube or TSphere, different kind of events will be called.
-  * TMouseEvent3D
-  * TMouseMoveEvent3D
-Those callback events have a different method signature and should be defined like that:
-<file pascal>
-procedure TForm1.DoOnCubeMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single;
-  RayPos, RayDir: TVector3D);
-begin
-  FIsMoving  := true;
-  FLastPoint := PointF(X, Y);
-end;
-procedure TForm1.DoOnCubeMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single;
-  RayPos, RayDir: TVector3D);
-begin
-  FIsMoving := false;
-end;
-procedure TForm1.DoOnCubeMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Single;
-  RayPos, RayDir: TVector3D);
-var LDiff : TPointF;
-begin
-  if FIsMoving then
-  begin
-    if (ssLeft in AShiftState) then
-	begin
-      LDiff := PointF(X, Y) - FLastPoint;
-      Dummy1.RotationAngle.Y := Dummy1.RotationAngle.Y + LDiff.X;
-	end;
-    FLastPoint := PointF(X, Y);
-  end;
-end;
-</file>
-==== HitTest Property ====
-The HitTest property is a very important value for user interaction and for performance. Because Firemonkey checks all controls on the form each time the mouse moves, many operations are caused. Especially ray cast operations on 3D objects are very costly!
-So our intention should be, to reduce those operations to a minimum. Any object that is not important for user interaction or ray-casting, should be disabled for intersection tests.
-<file pascal>
-GorillaCube1.HitTest := false;
-</file>
-But remember, if you disable intersection tests, no mouse events on that object will be called anymore!
-==== Bounding-Volume-History ====
-Gorilla3D offers an optimization for fast raycast intersection tests. This optimization is only available for derived classes of TGorillaMesh with a valid "Def" (TMeshDef) property.
-Take a further read for Bounding volume hierarchy at: [[https://en.wikipedia.org/wiki/Bounding_volume_hierarchy|https://en.wikipedia.org/wiki/Bounding_volume_hierarchy]]
-<file pascal>
-procedure TForm1.FormCreate(Sender: TObject);
-var LMeshDef : TMeshDef;
-begin
-  [...]
-  // setup bounding volume hierarchy
-  LMeshDef := GorillaMesh1.Def as TMeshDef;
-  LMeshDef.AcquireBVH();
-end;
-</file>
-To destroy a bounding volume hierarchy again, we have to call ReleasBVH().
-<file pascal>
-var LMeshDef : TMeshDef;
-begin
-  // destroy bounding volume hierarchy
-  LMeshDef := GorillaMesh1.Def as TMeshDef;
-  LMeshDef.ReleaseBVH();
-end;
-</file>
-Because setting up a bounding volume hierarchy causes some overhead data you should keep in mind to use this optimization only where it's useful.
-===== Keyboard Interaction =====
-In case you'll need keyboard interaction, best performance will be reached when key events are declared in the form itself.
-In the following example we setup a physics demo with a sphere. When cursor keys are down, an impulse will be applied to the sphere rigid body, which moves the object in space.
-<file pascal>
-uses
-  [...],
-  Gorilla.Sphere, Gorilla.Physics;
-type
-TForm1 = class(TForm)
-  GorillaSphere1: TGorillaSphere;
-  GorillaPhysicsSystem1: TGorillaPhysicsSystem;
-  procedure FormKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
-    Shift: TShiftState);
-  [...]
-end;
-[...]
-procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
-  Shift: TShiftState);
-var LImpulse : TPoint3D;
-    LBody : TQ3Body;
-begin
-  if (Key = vkLEFT) then
-    LImpulse := TPoint3D.Create(-1, 0, 0)
-  else if (Key = vkRIGHT) then
-    LImpulse := TPoint3D.Create(1, 0, 0)
-  else if (Key = vkUP) then
-    LImpulse := TPoint3D.Create(0, 0, 1)
-  else if (Key = vkDOWN) then
-    LImpulse := TPoint3D.Create(0, 0, -1);
-  // apply impulse on sphere
-  GorillaPhysicsSystem1.RemoteBodyImpulse(GorillaSphere1, LImpulse);
-end;
-</file>
-The usage of form key events is very rudimentary and may reach its limits very fast.
-===== 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 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 =====
-Interacting with gamepads in Firemonkey is not possible out of the box. But of course you can build your own component.
-Gorilla3D already provides support for gamepads in the TGorillaInputController and is very easy to use. Also combination of mouse and keyboard input is managable.
-===== Input-Controller =====
-Because most games and applications use hotkeys and sequences to interact with the 3D world.
-But handling all keyboard and mouse
-Read more: [[inputpolling|Input Polling]]
-Next step: [[android|Android]]