GLScene quickstart guide

preparations

First steps

• Get a new application with a form
• Drop GLScene onto the form
• Drop GLSceneViewer, align:=alnone, backgroundcolor:=clbtnface
• Doubleclick GLScene, GLSceneEditor appears as separate form
• in GLSceneEditor :
  add a camera (GLCamera1), position.Z:=10
  add a cube(Cube1), showaxes:=true;
  
• in the SceneViewer :
  camera:=GLCamera1;
  lighting:=false;
  
• in GLSceneEditor :
  cube1.texture.image:= just_some_256x256.bmp // or .jpg
  cube1.texture.disabled:=false;
  
• to the form :
  drop a trackbar,50..500, frequency:=50, position:=50; name:=focal;
  trackbar.onchange :
  GLCamera1.focallength:=focal.position;
  

next steps

• drop a trackbar,0..360, frequency:=10 ,position:=0; name:=xaxisrot;
  trackbar.onchange :
  cube1.pitchangle:=xaxisrot.position;
  
• drop a trackbar,0..360, frequency:=10 ,position:=0; name:=yaxisrot;
  trackbar.onchange :
  cube1.turnangle:=yaxisrot.position;
  
• drop a trackbar,0..360, frequency:=10 ,position:=0; name:=zaxisrot;
  trackbar.onchange :
  cube1.rollangle:=zaxisrot.position;
  

note

Results

• with the current camera position( direction = -Z, up = Y),
  the coordinate system is :
  X to the right
  Y up
  Z out of the screen
  The coordiante system is righthanded, meaning : with your right hand:
  if the thumb points to X, and the index finger points to Y, then the middle finger points to Z, right angles assumed
  
• Yes, rotations are measured in degrees, the underlying OpenGL does it this way.
  
• the GLSceneEditor(double click on the Scene) gives information about the OpenGL driver :
  the manufacturer, buffer and pixel depths, limitations, and supported extensions by clicking on the '?'
• There is a connection between point of view, near plane, far plane (frustrum) and the camera.focallength. The current implementation lets the object disappear when zooming in too close. glOrtho, the 'infinite projection' is currently not implemented.

with some tries

• the translation of the cube works the same way by setting the cube's position property.
  
• the cube's scale and cubedepth/cubeheight/cubewidth do the same, at least with just one cube. Scaling affects children if there are any. depht/width/heigth is the dimnsion.
  
• A texture on a cube/cone/disk/cylinder is painted right, on a
  - sphere it is painted upside down in version 073, it is fixed for later versions
  - torus/teapot it is somewhat strange, as it is uv mapped to xy
  - dodecahedron it is not painted at all
  
• textures added during designtime slow the system down. A truecolor texture (bmp) with a size of 2048^2 took half an hour to compile. Either use jpg images or load them later.

More

• add a performance monitor
  
  add a TTimer to the form, 1000ms, enabled, ontimer :
  Caption:=Format('%.2f FPS', [GLSceneViewer1.FramesPerSecond]);
  GLSceneViewer1.ResetPerformanceMonitor;
  
  set GLSceneViewer1.monitor:=true;
  
  that was it.
  
  
• add animation
  
  add a TGLCadencer to the form, scene:=GLScene1, onprogress :
  cube1.turnangle:=newtime*90;
  
  it turns with 90 degrees per second.
  
  
• add lighting
  
  try : cube1.material.frontproperties.texture.texturemode:=bmModulate;
  
  or
  
  remove the texture by cube1.texture.disabled:=true;
  GLSceneViewer1.lighting:=true;
  from GLSceneEdit :
  add a GLLightSource, diffuse:=clrWhite, position:=(5,5,5)
  
  as white light on a black body leaves black :
  
  cube1.material.frontproperties.diffuse:=clrwhite; // or whatever except black
  generally, the surface properties have be adapted for the light.
  
  a black surface doesn't reflect a color, wherever it may come from
  the material.frontproperties.ambient shouldn't be black for ambient light
  the material.frontproperties.specular shouldn't be black for specular light
  
  
• add fog
  
  in GLSceneViewer :
  set FogEnable:=true;
  FogColor:=clrMediumSpringGreen;
  FogStart:=0;
  FogEd:=20;
  FogMode:=fmLinear; // experiment with them
  
  

animating the objects

• as seen above, objects can be moved with the GLCadencer :
  GLCadencer.scene:=GLScene1,
  GLCadencer.onprogress :
  
  cube1.turnangle:=newtime*90;
  
• or as in the sound demo:
  var alpha : Single;
  GLSphere.Onprogress :
  // Move the red sphere (sound source) along an elliptic path
  alpha:=60*DegToRad(newTime);
  TSphere(Sender).Position.SetVector(sin(alpha)*2, 0.5, cos(alpha)*5, 1);
  

adding sound

• add a soundlibrary with a sound *.wav
• add an FMod
  

       GLSFMOD.Cadencer:=GLCadencer1;
       GLSFMOD.Listener:=_an_object;    // here the mickey
       GLSFMOD.Pause:=false;            // it plays now
       GLSFMOD.updatefrequency:=10;     // the soundprocessor is updated with new position information
    

• Sphere.Behaviours:=Soundemitter;
• Sphere.XCollection.SoundEmitter._some_properties

selecting objects

• attach a mousemove event to the GLSceneViewer
  VAR pick : TGLCustomSceneObject; // local
  VAR oldpick : TGLCustomSceneObject; //global
  

•   
   pick:=(GLSceneViewer1.GetPickedObject(x, y) as TGLCustomSceneObject);
   if (pick<>oldpick) then begin
    if assigned(oldpick) then   oldpick.material.frontproperties.emission.color:=clrblack;
    if assigned(pick) then
     pick.material.frontproperties.emission.color:=clrred;
    oldpick:=pick;
   end;
  

here the emission color was used to highlite the selected object.
It may make sense to store the old emission.color
  oldcolor:THomogeneousFltVector;

where THomogeneousFltVector is defined in Geometry

Materials

Textures

• 4096x4096
• 2048x2048
• 1024x..
• ..x512
• ..x256
• ..x128
• ..x64
• ..x32
• 16x16
• 1024x64
• 512x128

USES ......,JPEG; // include the jpeg library

procedure tform1.Formcreate(sender:tobject);
var jpg:TJPEGImage;
begin
 jpg:=TJPEGImage(cube1.material.texture.image); // for a texture designtime assigned to cube1
 jpg.assign(cube1.material.texture.image);
 ..
end;