Elite on the BBC Micro

# Moving: MVEIT (Part 7 of 9) (6502SP version)

```       Name: MVEIT (Part 7 of 9)                               [View in context]
Type: Subroutine
Category: Moving
Summary: Move current ship: Rotate ship's orientation vectors by pitch/roll
Deep dive: Orientation vectors
Pitching and rolling

This routine has multiple stages. This stage does the following:

* Rotate the ship's orientation vectors according to our pitch and roll

As with the previous step, this is all about moving the other ships rather
than us (even though we are the one doing the moving). So we rotate the
current ship's orientation vectors (which defines its orientation in space),
by the angles we are "moving" the rest of the sky through (alpha and beta, our
roll and pitch), so the ship appears to us to be stationary while we rotate.

LDY #9                 \ Apply our pitch and roll rotations to the current
JSR MVS4               \ ship's nosev vector

LDY #15                \ Apply our pitch and roll rotations to the current
JSR MVS4               \ ship's roofv vector

LDY #21                \ Apply our pitch and roll rotations to the current
JSR MVS4               \ ship's sidev vector
```