GLS场景采摘

Question

我一直在使用 GLSceneViewer1.Buffer.GetPickedObject( x, y ) 在每个选择演示的 GLViewerMouseDown 事件中选择 GLscene 对象。我需要 select 一个对象，更改颜色，单击鼠标左键，然后再单击鼠标左键 deselect，如果另一个对象被 selected，则 deselect编辑。似乎 TGLSceneObject 需要一个属性 IsPicked : boolean 对我来说能够实现这一点。如果有人知道在不修改 GLScene 的情况下这样做会很酷。这是我编写的代码，它可以工作，但不能。 SetSelected( Selected, SelectedColor ) 只是改变 selected 对象的颜色。

procedure TForm32.GLSceneViewer1MouseDown( Sender : TObject; Button : TMouseButton; Shift : TShiftState; X, Y : Integer );
  var
    Selected : TGLSceneObject;
    AButton : TGLMouseButton;
  begin
    AButton := TGLMouseButton( Button );

    // if an object is picked...
    Selected := ( GLSceneViewer1.Buffer.GetPickedObject( x, y ) as TGLSceneObject );

      case AButton of
        mbLeft:
          begin
              if( Selected <> UnSelected ) then
                begin
                   if( Assigned( Selected ) ) then
                      begin
                        SetSelected( Selected, SelectedColor );
                        StatusBar1.Panels[0].Text := 'Selected';
                        UnSelected := Selected;
                      end
                   else
                    if( not Assigned( Selected ) ) then
                      begin
                        UnSelected.Material.FrontProperties.Emission.Color:= clrBlack;
                        UnSelected.Material.FrontProperties.Ambient.Color := clrGray20;
                        UnSelected.Material.FrontProperties.Diffuse.Color := clrGray80;
                        StatusBar1.Panels[0].Text := 'Unselected';
                        UnSelected := Selected;
                      end;
                end;
          end;
      end;
  end;

对我来说这会更容易：

procedure TForm32.GLSceneViewer1MouseDown( Sender : TObject; Button : TMouseButton; Shift : TShiftState; X, Y : Integer );
  var
    Selected : TGLSceneObject;
  begin
    Selected := ( GLSceneViewer1.Buffer.GetPickedObject( x, y ) as TGLSceneObject );
      if( not Selected.IsPicked ) then
        SetSelected( Selected, SelectedColor )
      else
        SetSelected( Selected, UnSelectedColor );
   end;

Answer 1

在争论我是否应该通过修改源代码来破坏我的 GLScene 库，这将需要分发源代码，这对我来说似乎不太理想，我想出了以下代码作为回答我的问题。答案似乎是维护一个我命名为 CurrentSelection 的 TGLSceneObject 缓冲区对象。

procedure TForm32.GLSceneViewer1MouseDown( Sender : TObject; Button : TMouseButton; Shift : TShiftState; X, Y : Integer );
  //CurrentSelection : TGLSceneObject; //TForm private declaration
  //Selected : TGLSceneObject; //TForm private declaration
  begin
    Selected := ( GLSceneViewer1.Buffer.GetPickedObject( x, y ) as TGLSceneObject );
      if( Selected <> nil ) then  //Avoid access violation error
        begin
          if( Assigned( CurrentSelection ) ) then //If CurrentSelection is not nil deselect it
            SetSelectedColor( CurrentSelection, UnSelectedColor );

          if( Selected = CurrentSelection ) then 
            begin 
              //has the same object been clicked then deselect it and clear the buffer object
              SetSelectedColor( Selected, UnSelectedColor );
              CurrentSelection := nil;
            end
          else
            begin 
              //if no object is selected select an object, set the color and assign the object to the buffer
              SetSelectedColor( Selected, SelectedColor );
              CurrentSelection := Selected;
            end;
        end;
  end;

设置 TGLSceneObject 的颜色

procedure TForm32.SetSelectedColor( Selected : TGLSceneObject; Color : TColorVector );
  begin
    Selected.Material.FrontProperties.Ambient.Color := Color;
    Selected.Material.FrontProperties.Diffuse.Color := Color;
    Selected.Material.FrontProperties.Emission.Color:= clrBlack;
  end;

上面的代码不检查使用了哪个鼠标按钮，但我可以select一个对象，deselect这个对象，当另一个对象被select编辑时deselect当前对象。

我需要修改它以将 deselected 对象设置为其原始 colour/material 但这应该相对简单。

干杯:)

GLS场景采摘

GLScene picking

delphi

delphi-xe3

glscene