Clarify how to get eye point in Sky::ScreenPtHitsSky

1 files changed, 5 insertions, 0 deletions

diff --git a/dev/a6-harold/sky.cc b/dev/a6-harold/sky.cc
index 0819ebe..bc08ca0 100644
--- a/dev/a6-harold/sky.cc
+++ b/dev/a6-harold/sky.cc
@@ -28,6 +28,11 @@ void Sky::Init(ShaderProgram *stroke3d_shaderprog) {
 bool Sky::ScreenPtHitsSky(const Matrix4 &view_matrix, const Matrix4 &proj_matrix,
                         const Point2 &normalized_screen_pt, Point3 *sky_point)
 {
+    // You will need the eye point, this can be 
+    // determined from the view matrix as follows:
+    Matrix4 camera_matrix = view_matrix.Inverse();
+    Point3 eye = camera_matrix.ColumnToPoint3(3);
+    
     // TODO: Stitch together your worksheet implementation of this method
     return true;
 }