how to do a rotated mirror?

[noeska]

i came up with this. But rotation still is no good:

//create the reflection texture
procedure CreateTexture;
var
  CP: array [0..3] of Double;
begin
  //set up clipping plane
  cp[0]:=0.0; //x
  cp[1]:=0.0; //y
  cp[2]:=0.000001; //z has to be somewhat larger then 0
  cp[3]:=0.0; //w

  //set up the viewport
  glViewport(0, 0, M_SIZE, M_SIZE);

  //clear the buffers
  glClearColor(0.0, 0.0, 0.1, 0.0);        //  Background color
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);

  //set the camera pos
  glLoadIdentity;
  glLoadmatrixd(@matM);

//  gltranslatef(mirrorpos.x,mirrorpos.y,mirrorpos.z);
//  glrotatef(mirrorrot.x,1,0,0);
 // glrotatef(mirrorrot.y,0,1,0);
 // glrotatef(mirrorrot.z,0,0,1);


  //mirror it
  glScalef(1.0, 1.0, -1.0);

  //enable clipping plane
  glClipPlane(GL_CLIP_PLANE0, @CP);
  glEnable(GL_CLIP_PLANE0);

  //translate the mirror from its position back to 0
  //actualy the scene is rotated with the reverse matrix of the mirror?
  glrotatef(-mirrorrot.y,0,1,0);
  glrotatef(-mirrorrot.x,1,0,0);
  glrotatef(-mirrorrot.z,0,0,1);
  gltranslatef(-mirrorpos.x,-mirrorpos.y,-mirrorpos.z);

  //draw the scene...
  DrawObjects;

  //disable the clipping plane
  glDisable(GL_CLIP_PLANE0);

  //copy the color buffer to a texture creating a new texture if necessary
  if &#40;Reflection <> 0&#41; then
  begin
    glBindTexture&#40;GL_TEXTURE_2D, Reflection&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
      GL_LINEAR&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
      GL_LINEAR&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
      GL_CLAMP&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
      GL_CLAMP&#41;;
    glCopyTexSubImage2D&#40;GL_TEXTURE_2D, 0, 0, 0, 0, 0,
      M_SIZE, M_SIZE&#41;;
  end else
  begin
    glGenTextures&#40;1, @Reflection&#41;;
    glBindTexture&#40;GL_TEXTURE_2D, Reflection&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
      GL_LINEAR&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
      GL_LINEAR&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,
      GL_CLAMP&#41;;
    glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,
      GL_CLAMP&#41;;
    glCopyTexImage2D&#40;GL_TEXTURE_2D, 0, GL_RGB, 0, 0,
      M_SIZE, M_SIZE, 0&#41;;
  end;

  //restore the viewport
  glViewport&#40;0, 0, WND_XSIZE, WND_YSIZE&#41;;
end;

//calculate the texture coordinates for a vertex and send them to OpenGL
procedure RenderVertex&#40;vX, vY, vZ&#58; Single&#41;;
var
  tX, tY, tZ&#58; Double;
const
  vp&#58; TGLVectori4 = &#40;0,0,1,1&#41;; //dummy viewport
begin
  //calculate the window coordinates of the vertex
  gluProject&#40;vX, vY, vZ, matM, matP, vp, @tX, @tY, @tZ&#41;;
  //use the window coords as texture coords
  glTexCoord2f&#40;tX, tY&#41;;
  glVertex3f&#40;vX, vY, vZ&#41;;
end;

//  Function to draw the actual scene
procedure glDraw&#40;&#41;;
var
 i,j&#58; integer;
begin

 Time &#58;= GetTickCount / 1000.0;

 //set mirror pos...
// mirrorpos.x&#58;=Sin&#40;Time * 1.3&#41;;
// mirrorpos.y&#58;=Sin&#40;Time * 1.3&#41;;
// mirrorpos.z&#58;=Sin&#40;Time * 1.3&#41;;

 mirrorrot.x&#58;=Sin&#40;Time * 1.3&#41; * 60;
 mirrorrot.y&#58;=Sin&#40;Time * 1.4&#41; * 60;
 mirrorrot.z&#58;=Sin&#40;Time * 1.5&#41; * 60;

 glLoadIdentity;

 //set camera pos...
 gltranslatef&#40;0,-5,-20&#41;;
// glrotatef&#40;90,0,1,0&#41;;

 //Get the modelview and projection matrices
 glGetDoublev&#40;GL_MODELVIEW_MATRIX, @matM&#41;;
 glGetDoublev&#40;GL_PROJECTION_MATRIX, @matP&#41;;

 CreateTexture; //create the mirror texture

 glClearColor&#40;0.0, 0.0, 0.2, 0.0&#41;;        //  Background color
 glClear&#40;GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT&#41;; //comment this line out the see the last renderend mirror scene
 glLoadIdentity&#40;&#41;;
 glLoadmatrixD&#40;@matM&#41;;

 glLightfv&#40;GL_LIGHT0, GL_POSITION, @lp&#41;; //position light

 //render the mirror
 glColor4f&#40;1, 1, 1, 0.8&#41;; // make the water transparent.
 gldisable&#40;GL_LIGHTING&#41;;
 glenable&#40;GL_TEXTURE_2D&#41;;
 glBindTexture&#40;GL_TEXTURE_2D, Reflection&#41;; //use calculated mirror texture
 glpushmatrix&#40;&#41;;
  //place the mirror
  gltranslatef&#40;mirrorpos.x,mirrorpos.y,mirrorpos.z&#41;;

  glrotatef&#40;mirrorrot.z,0,0,1&#41;;
  glrotatef&#40;mirrorrot.x,1,0,0&#41;;
  glrotatef&#40;mirrorrot.y,0,1,0&#41;;


  //do the actual rendering
  //by using RenderVertex the texture coords are recalculated
  for I &#58;= -&#40;mirrorsize div 2&#41; to &#40;mirrorsize div 2&#41; - 1 do
   begin
    glBegin&#40;GL_QUAD_STRIP&#41;;
    for J &#58;= -&#40;mirrorsize div 2&#41; to &#40;mirrorsize div 2&#41; do
    begin
      RenderVertex&#40;I / M_DETAIL - 0.5,
        J / M_DETAIL - 0.5, 0.0&#41;;
      RenderVertex&#40;&#40;I + 1&#41; / M_DETAIL - 0.5,
        J / M_DETAIL - 0.5, 0.0&#41;;
    end;
    glEnd;

   end;
 glpopmatrix&#40;&#41;;
 gldisable&#40;GL_TEXTURE_2D&#41;;
 glenable&#40;GL_LIGHTING&#41;;

 //draw the scene...
 drawobjects&#40;&#41;;

 // Flush the OpenGL Buffer
 glFlush&#40;&#41;;

end;

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