|
Table of Contents
gluLookAt - define a viewing transformation
void
gluLookAt( GLdouble eyeX,
GLdouble eyeY,
GLdouble eyeZ,
GLdouble centerX,
GLdouble centerY,
GLdouble centerZ,
GLdouble upX,
GLdouble upY,
GLdouble upZ )
eqn not supported
- eyeX, eyeY, eyeZ
- Specifies the position of
the eye point.
- centerX, centerY, centerZ
- Specifies the position of the reference
point.
- upX, upY, upZ
- Specifies the direction of the up vector.
gluLookAt
creates a viewing matrix derived from an eye point, a reference point indicating
the center of the scene, and an UP vector.
The matrix maps the reference
point to the negative z axis and the eye point to the origin. When a typical
projection matrix is used, the center of the scene therefore maps to the
center of the viewport. Similarly, the direction described by the UP vector
projected onto the viewing plane is mapped to the positive y axis so that
it points upward in the viewport. The UP vector must not be parallel to
the line of sight from the eye point to the reference point.
Let
eqn not
supported
Let UP be the vector $("upX", "upY", "upZ")$.
Then normalize
as follows: eqn not supported
eqn not supported
Finally, let $s ~=~ f ~times~
UP sup prime$, and $u ~=~ s ~times~ f$.
M is then constructed as follows:
eqn not supported
and gluLookAt is equivalent to glMultMatrixf(M); glTranslated
(-eyex, -eyey, -eyez);
glFrustum(3G)
, gluPerspective(3G)
Table of Contents
|
