starman

04-29-2003, 09:03 AM

I'm trying to fully understand the relationship between the "local" and

"grand, fixed" coordinate systems from Chapter 3 of the red book.

Relative to the grand, fixed coordinate system, where will the sphere be

drawn below?

// View transformations

glRotatef(90.0, 0, 1, 0);

glTranslatef(-10.0, 0.0, 0.0);

// Modeling transformations

glTranslatef(20.0, 0.0, 0.0);

gluSphere(...)

Looking at it as a local coordinate system that gets rotated 90 degrees,

the "local" positive X is the positive Z in the "grand, fixed" system.

This would put the sphere at (0.0, 0.0, 10.0) in the grand, fixed

system, correct?

"grand, fixed" coordinate systems from Chapter 3 of the red book.

Relative to the grand, fixed coordinate system, where will the sphere be

drawn below?

// View transformations

glRotatef(90.0, 0, 1, 0);

glTranslatef(-10.0, 0.0, 0.0);

// Modeling transformations

glTranslatef(20.0, 0.0, 0.0);

gluSphere(...)

Looking at it as a local coordinate system that gets rotated 90 degrees,

the "local" positive X is the positive Z in the "grand, fixed" system.

This would put the sphere at (0.0, 0.0, 10.0) in the grand, fixed

system, correct?