HP Workstation c3650 OpenGL 1.1 Reference for HP-UX 11.x - Page 269

L gluLookAt Chapter 10 gluLookAt gluLookAt: define a viewing transformation. C Specification void gluLookAt( GLdouble eyeX. GLdouble eyeY, GLdouble eyeZ, GLdouble centerX, GLdouble centerY, GLdouble centerZ, GLdouble upX, GLdouble upY, GLdouble upZ) Parameters 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. Description 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 F = (centerx - eyex, centery - eyey, centerz- eyez), let up be the vector (upX, upY, upZ), and then normalize as follows: f = ---FF------ and up= ---uu----pp---- Finally, let s = f × up, and u = s × f. M is then constructed as follows: 269