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GL_Select

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Betreff des Beitrags: GL_Select

Verfasst: Sa Jun 28, 2008 21:07

DGL Member

Registriert: Mi Jul 21, 2004 22:39
Beiträge: 360
Wohnort: UK, Scotland

Im trying to implement a GL_Select picker in a map editor im making but it just returns 0 hits. I have used This tutorial as a basis. Before the code below, FInSelection is filled with every face which could have been picked by the user (Based on the Bounding Box of each face), its also sorted so that the first one will be the closest to the Camera. Any help would be appreciated.

Code:

 // Store our Viewport
 glGetIntegerv(GL_VIEWPORT, @viewport);
 // Tell OpenGL the size of our select buffer
 glSelectBuffer(512, @SelectBuffer);
 // Change our render mode to GL_SELECT
 glRenderMode(GL_SELECT);
 // Init the namestack
 glInitNames;
 glPushName(0);
 glMatrixMode(GL_PROJECTION);
 glPushMatrix;
  glLoadIdentity;
  // Zoom the view to one pixel around the mouse position
  gluPickMatrix(x, y, 1.0, 1.0, viewport);
  gluPerspective(45.0, OGLGrid.OGLWidth/OGLGrid.OGLHeight, 4, 40000);
  // Now we draw our scene in the select render mode
  glMatrixMode(GL_MODELVIEW);
 
  glPushMatrix;
   OGLGrid.Prepare2D(OGLGrid.OGLWidth,OGLGrid.OGLHeight);
   glTranslatef(OGLGrid.GetFWidth / 2 + OGLGrid.PosX,OGLGrid.GetFHeight / 2 + OGLGrid.PosY+15,0);
 
    glInitNames;
    glPushName(0);
    for i := 0 to FInSelection_Count-1 do
    begin
     glLoadName(i);
     TFME_Map_Visual_Object(FInSelection[i]).Render(OGLGrid,True);
    end;
 
   OGLGrid.End2D;
  glPopMatrix;
 
  glMatrixMode(GL_PROJECTION);
 glPopMatrix;
 
 Hits := glRenderMode(GL_RENDER);
 glMatrixMode(GL_MODELVIEW);
 
 if Hits > 1 then
 begin
  Add(FInSelection[SelectBuffer[3]]);
  OGLGrid.UpdateGrids;
 end;
end;

_________________
Free Map Editor - Game Requirements - Stucuk.Net
-Stu

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Stucuk

Betreff des Beitrags:

Verfasst: So Jun 29, 2008 04:54

DGL Member

Registriert: Mi Jul 21, 2004 22:39
Beiträge: 360
Wohnort: UK, Scotland

Guess it helps if you enable GL_VERTEX_ARRAY before sending data using Vertex Arrays(Doh!).

_________________
Free Map Editor - Game Requirements - Stucuk.Net
-Stu

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Stucuk

Betreff des Beitrags:

Verfasst: So Jun 29, 2008 18:51

DGL Member

Registriert: Mi Jul 21, 2004 22:39
Beiträge: 360
Wohnort: UK, Scotland

Ran into another problem, this one shouldn't be as simple as the first. GL_Select seems to be failing somtimes, in most cases it works fine, but iv found a map with an area where it gives no hits, yet there is face's in that area which are being passed to it. The images below shows in red the faces which are being sent to the GL_Select for Picking, the Yellow area is where its generating no hits and the green dot is where i clicked.

Bild

- Download ~1.36MB (EXE + Sample Map)
Note: 3D View doesn't have any picking ability, only the Grid Modes have the ability.

Source:

Code:

 
procedure TFME_Map_Selected.ProcessClick(OGLGrid : TOGLGrid; X, Y: Integer);
var
 I : Cardinal;
 VisualObject : TFME_Map_Visual_Object;
 Viewport     : TVector4i;
 SelectBuffer : array[0..512] of TGLUInt;
 Hits         : Integer;
 Hit          : TGLUInt;
begin
 if OGLGrid.FObjectsCount < 1 then exit;
 
 FInSelection_Count := 0;
 // This bit generates the list of possible faces that could be selected based on there bounding box
 for I := OGLGrid.FObjectsCount-1 downto 0 do
 begin
  VisualObject := OGLGrid.FObjects[OGLGrid.FObjectsOrder[I].ID];
  if IsInBounds(OGLGrid,X,Y,VisualObject) then
   AddInSelection(VisualObject);
 end;
 
 if FInSelection_Count < 1 then exit; // If no face has the X,Y in there bounds then exit.
 
 //START OF GL_SELECT
 
 // Store our Viewport
 glGetIntegerv(GL_VIEWPORT, @viewport);
 // Tell OpenGL the size of our select buffer
 FillChar(SelectBuffer,SizeOf(SelectBuffer),0);
 glSelectBuffer(512, @SelectBuffer);
 // Change our render mode to GL_SELECT
 glRenderMode(GL_SELECT);
 // Init the namestack
 glInitNames;
 glPushName(0);
 glMatrixMode(GL_PROJECTION);
 glPushMatrix;
  glLoadIdentity;
  // Zoom the view to one pixel around the mouse position
  gluPickMatrix(x, y, 1.0, 1.0, viewport);
  glOrtho(0, OGLGrid.OGLWidth, 0, OGLGrid.OGLHeight, -1, 1);
  // Now we draw our scene in the select render mode
  glMatrixMode(GL_MODELVIEW);
   //START OF "RENDERING"
 
 
  glClear(GL_DEPTH_BUFFER_BIT or GL_COLOR_BUFFER_BIT);
  glPushMatrix;
    glTranslatef(OGLGrid.GetFWidth / 2 + OGLGrid.PosX,OGLGrid.GetFHeight / 2 + OGLGrid.PosY+15,0);
 
    glEnableClientState(GL_VERTEX_ARRAY);
 
    glInitNames;
    glPushName(0);
 
    glDisable(GL_CULL_FACE);
    for i := 0 to FInSelection_Count-1 do
    begin
     glLoadName(i);
     TFME_Map_Visual_Object(FInSelection[i]).Render(OGLGrid,True);
    end;
    glEnable(GL_CULL_FACE);
 
    glDisableClientState(GL_VERTEX_ARRAY);
 
  glPopMatrix;
 
   //END OF "RENDERING"
 
  glMatrixMode(GL_PROJECTION);
 glPopMatrix;
 
 Hits := glRenderMode(GL_RENDER);
 glMatrixMode(GL_MODELVIEW);
 
 //END OF GL_SELECT
 
 if Hits > 1 then
 if SelectBuffer[3] < FInSelection_Count then
 begin
  Add(FInSelection[SelectBuffer[3]]);
  OGLGrid.UpdateGrids;
 end;
end;

_________________
Free Map Editor - Game Requirements - Stucuk.Net
-Stu

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