glTF: constraine camera move in orbit mode

Not to get too close to / too far from the model.
Too close means move into the model.

Change-Id: Ie25d87c88093d4baaf98f13ab8239263b5e1bf66

avmedia/source/opengl/oglwindow.cxx

@@ -21,6 +21,7 @@ OGLWindow::OGLWindow( glTFHandle& rHandle, OpenGLContext& rContext, Window& rEve
     , m_bVisible ( false )
     , m_aLastMousePos(Point())
     , m_bIsOrbitMode( false )
+    , m_fCameraDistance(0.0)
 {
 }
 
@@ -261,6 +262,16 @@ IMPL_LINK(OGLWindow, CameraHandler, VclWindowEvent*, pEvent)
                         if(nCode == KEY_A)vMoveBy -= vStrafe*(0.0005f*fModelSize);
                         if(nCode == KEY_D)vMoveBy += vStrafe*(0.0005f*fModelSize);
                     }
+                    else
+                    {
+                        // Limit zooming in orbit mode
+                        m_fCameraDistance += vMoveBy.z;
+                        if (m_fCameraDistance < 0.75 * fModelSize || m_fCameraDistance > 2 * fModelSize)
+                        {
+                            m_fCameraDistance -= vMoveBy.z;
+                            vMoveBy = glm::vec3(0.0);
+                        }
+                    }
                 }
                 gltf_renderer_move_camera(&m_rHandle, vMoveBy.x, vMoveBy.y, vMoveBy.z, 0.0);
             }
@@ -275,6 +286,12 @@ IMPL_LINK(OGLWindow, CameraHandler, VclWindowEvent*, pEvent)
                 {
                     gltf_orbit_mode_start(&m_rHandle);
                     m_bIsOrbitMode = true;
+                    // Set default camera distance
+                    glm::vec3 vEye;
+                    glm::vec3 vView;
+                    glm::vec3 vUp;
+                    gltf_get_camera_pos(&m_rHandle, &vEye,&vView,&vUp);
+                    m_fCameraDistance = vEye.z - gltf_get_model_center_pos(&m_rHandle)->z;
                 }
             }
             else if(nCode == KEY_F)

avmedia/source/opengl/oglwindow.hxx

@@ -68,9 +68,11 @@ private:
     glTFHandle& m_rHandle;
     OpenGLContext& m_rContext;
     Window& m_rEventHandler;
+
     bool m_bVisible;
     Point m_aLastMousePos;
     bool m_bIsOrbitMode;
+    double m_fCameraDistance;
 };
 
 } // namespace ogl