OpenGL Fog

// state is a SceneState pointer
   // rimage is a SceneRenderImage pointer

   RectI viewport;
   glMatrixMode(GL_PROJECTION);
   glPushMatrix();
   dglGetViewport(&viewport);

   GLfloat fogColor[4];
   fogColor[0] = 255;//state->getFogColor().red;
   fogColor[1] = 0.0f;//state->getFogColor().green;
   fogColor[2] = 0.0f;//state->getFogColor().blue;
   fogColor[3] = 1.0f;

   glEnable(GL_FOG);
   glFogi(GL_FOG_MODE, GL_LINEAR);
   glHint(GL_FOG_HINT, GL_NICEST);
   glFogfv(GL_FOG_COLOR, fogColor);
   glFogf(GL_FOG_DENSITY, 0.35f);
   glFogf(GL_FOG_START, 0.0f);//state->getFogDistance());
   glFogf(GL_FOG_END, 50.0f);//state->getVisibleDistance());

   if (state->isTerrainOverridden() == false) {
      state->setupObjectProjection(this);
   } else {
      state->setupBaseProjection();
   }

   glMatrixMode(GL_MODELVIEW);
   glPushMatrix();
   dglMultMatrix(&mRenderObjToWorld);
   glScalef(mObjScale.x, mObjScale.y, mObjScale.z);

   F64 frustumParam[6];
   dglGetFrustum(&frustumParam[0], &frustumParam[1],
                 &frustumParam[2], &frustumParam[3],
                 &frustumParam[4], &frustumParam[5]);

   MatrixF cameraToObject;
   dglGetModelview(&cameraToObject);
   cameraToObject.inverse();
   Point3F osCamPoint(0, 0, 0);
   cameraToObject.mulP(osCamPoint);
   sgComputeOSFrustumPlanes(frustumParam,
                            cameraToObject,
                            osCamPoint,
                            m_Frustum[FRONT],
                            m_Frustum[LEFT],
                            m_Frustum[RIGHT],
                            m_Frustum[BOTTOM],
                            m_Frustum[TOP]);

   // CODE REMOVED FOR SIMPLICITY
   // ... cull blocks
   // ... enable/setup states, pointers, buffers
   // ... render
   // ... disable buffers, pointers, states

   glDisable(GL_FOG);
   glMatrixMode(GL_MODELVIEW);
   glPopMatrix();

   glMatrixMode(GL_PROJECTION);
   glPopMatrix();
   glMatrixMode(GL_MODELVIEW);
   dglSetViewport(viewport);