Skip to navigation

BBC Micro Elite

Drawing planets: PLS5

Name: PLS5 [View in context] Type: Subroutine Category: Drawing planets Summary: Calculate roofv_x / z and roofv_y / z
Calculate the following divisions of a specified value from one of the orientation vectors (in this example, roofv): (XX16+2 K2+2) = roofv_x / z (XX16+3 K2+3) = roofv_y / z Arguments: X Determines which of the INWK orientation vectors to divide: * X = 15: divides roofv_x and roofv_y * X = 21: divides sidev_x and sidev_y INWK The planet's ship data block
.PLS5 { JSR PLS1 \ Call PLS1 to calculate the following: STA K2+2 \ STY XX16+2 \ K+2 = |roofv_x / z| \ XX16+2 = sign of roofv_x / z \ \ i.e. (XX16+2 K2+2) = roofv_x / z \ \ and increment X to point to roofv_y for the next call JSR PLS1 \ Call PLS1 to calculate the following: STA K2+3 \ STY XX16+3 \ K+3 = |roofv_y / z| \ XX16+3 = sign of roofv_y / z \ \ i.e. (XX16+3 K2+3) = roofv_y / z \ \ and increment X to point to roofv_z for the next call RTS \ Return from the subroutine }