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Lots of comments about what LookAt is doing

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This commit is contained in:
Eryn Wells 2014-08-03 20:11:22 -07:00
parent c2a4372467
commit 5ac721d601
1 changed files with 11 additions and 0 deletions
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11
src/camera.cc
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@ -122,10 +122,17 @@ Camera::LookAt(const Vector3& pt)
const Double upLength = mUp.length(); const Double upLength = mUp.length();
const bool isLeftHanded = IsLeftHanded(); const bool isLeftHanded = IsLeftHanded();
/* Orient the camera towards the point. */
mDirection = (pt - mOrigin).normalize(); mDirection = (pt - mOrigin).normalize();
/* TODO: Check for zero length direction vector. */ /* TODO: Check for zero length direction vector. */
/* /*
* Create a new right vector, normalized and perpendicular to the plane
* containing the Y unit vector and direction vector.
*
* The up vector is perpendicular to the plane containing the new right
* vector and the direction vector.
*
* TODO: This is always the Y vector. POV-Ray has a sky vector, which * TODO: This is always the Y vector. POV-Ray has a sky vector, which
* specifies the vector along which LookAt pans and tilts the camera. It * specifies the vector along which LookAt pans and tilts the camera. It
* might be worth looking into, at some point. * might be worth looking into, at some point.
@ -133,6 +140,10 @@ Camera::LookAt(const Vector3& pt)
mRight = Vector3::Y.cross(mDirection).normalize(); mRight = Vector3::Y.cross(mDirection).normalize();
mUp = mDirection.cross(mRight); mUp = mDirection.cross(mRight);
/*
* Now, fix up the direction, right, and up vectors so that their magnitudes
* match what they were before the move.
*/
mDirection *= directionLength; mDirection *= directionLength;
mRight *= isLeftHanded ? rightLength : -rightLength; mRight *= isLeftHanded ? rightLength : -rightLength;
mUp *= upLength; mUp *= upLength;