Norman Vine:

Note that SSG and OpenGL use different representations
of Matrices.

1) SSG is row major and OpenGL is column major

2) SSG uses a Z is up whereas conventionally OpenGL uses
   Z is pointing into the screen
   ie this just requires swapping the Y and the Z axis < columns >
   and negating the new Y column

3) Now since SSG eventually calls OpenGL SSG must do this
   for us behind the scenes or else things just wouldn't work
   so inorder to get Clouds3D to render in the proper location
   we should just need to use the Matrix that SSG uses for a Camera
   Matrix and pass this directly to the Clouds3D Camers

diff --git a/simgear/scene/sky/clouds3d/SkySceneLoader.cpp b/simgear/scene/sky/clouds3d/SkySceneLoader.cpp
index 099eb54b9d480e7a4de1a2efdb2e65cb35479307..288133fc462f4116b005a8c40f76e3117cbad47f 100644 (file)
--- a/simgear/scene/sky/clouds3d/SkySceneLoader.cpp
+++ b/simgear/scene/sky/clouds3d/SkySceneLoader.cpp
@@ -197,54 +197,23 @@ void SkySceneLoader::Resize(  double w, double h )
 }
 
 void SkySceneLoader::Draw( sgMat4 mat )
-{/* need this if you want to look at FG matrix
-       if ( _ssgCurrentContext == NULL )
-  {
-    cout<< "ssg: No Current Context: Did you forgot to call ssgInit()?" ; char x; cin >> x;
-  }
-  
-  ssgForceBasicState () ;
-  */
-  sgMat4 test, m, *pm, viewmat,  cameraMatrix;
-  pm = &m;
-  sgSetVec4(mat[3], cam_pos[0], cam_pos[1], cam_pos[2], SG_ONE);
-  // at this point the view matrix has the cloud camera position relative to cloud origin
-  // now transform to screen coordinates
-  sgTransposeNegateMat4 ( viewmat, mat ) ;
-
-  sgCopyMat4    ( cameraMatrix, my_copy_of_ssgOpenGLAxisSwapMatrix ) ;
-  sgPreMultMat4 ( cameraMatrix, viewmat ) ;
-  
-  //sgCopyMat4 ( test, cameraMatrix );
-  
-  //printf( "\nSkyworks ViewModel matrix\n" );
-       //cout << test[0][0] << " " << test[1][0] << " " << test[2][0] << " " << test[3][0] << endl;
-  //cout << test[0][1] << " " << test[1][1] << " " << test[2][1] << " " << test[3][1] << endl;
-  //cout << test[0][2] << " " << test[1][2] << " " << test[2][2] << " " << test[3][2] << endl;
-  //cout << test[0][3] << " " << test[1][3] << " " << test[2][3] << " " << test[3][3] << endl;
-       
-        // this is the cameraview matrix used by flightgear to render scene
-       //_ssgCurrentContext->getModelviewMatrix( m );
-       
-  glMatrixMode ( GL_MODELVIEW ) ;
-  glLoadIdentity () ;
-  glLoadMatrixf( (float *) cameraMatrix );
-  
-  //sgCopyMat4( test, m );
+{
+    sgMat4 cameraMatrix;
 
-       pCam->SetModelviewMatrix( (float *) cameraMatrix );
-  
-  //printf( "\nFG modelview matrix\n" );
-  //cout << test[0][0] << " " << test[1][0] << " " << test[2][0] << " " << test[3][0] << endl;
-  //cout << test[0][1] << " " << test[1][1] << " " << test[2][1] << " " << test[3][1] << endl;
-  //cout << test[0][2] << " " << test[1][2] << " " << test[2][2] << " " << test[3][2] << endl;
-  //cout << test[0][3] << " " << test[1][3] << " " << test[2][3] << " " << test[3][3] << endl;
+    // sgCopyMat4(cameraMatrix,mat);    
+    // or just 
+    ssgGetModelviewMatrix(cameraMatrix);
 
-       SceneManager::InstancePtr()->Display(*pCam);
+    glMatrixMode ( GL_MODELVIEW ) ;
+    glLoadIdentity () ;
+    glLoadMatrixf( (float *) cameraMatrix );
+  
+    pCam->SetModelviewMatrix( (float *) cameraMatrix );
+  
+    SceneManager::InstancePtr()->Display(*pCam);
        
-       //pLight->Display(); // draw the light position to  debug with sun position
-
-  glMatrixMode ( GL_MODELVIEW ) ;
-  glLoadIdentity () ;
+    //pLight->Display(); // draw the light position to  debug with sun position
 
+    glMatrixMode ( GL_MODELVIEW ) ;
+    glLoadIdentity () ;
 }