Can you be more specific ?
What do you need to be explained ?
Cartesian coordinates work, in Blitz, as any other graphic language: x coordinates goes from 0---> screen width; for example, in a 640 X 480 screen, 0 is the very left edge, while 480 the very right one.
For y coordinates, they starts from up istead, and increase from 0 to screen height.
So, 0,0 is the upper left corner of the screen; 640,0 is the upper right corner; 0,480 is the lower left corner, while 640,480 is the very lower right corner:
0,0 . . . . . . . . 640,0
.
.
.
0,480 . . . . . . . 640,480
So, if you want to move an astroship on the screen, and you want to move from left to right, you have to increase the ship's x coordinates; while if you want to move the ship up, you have to decrease its y coordinates.
Hope this helps,
Sergio.
What do you need to be explained ?
Cartesian coordinates work, in Blitz, as any other graphic language: x coordinates goes from 0---> screen width; for example, in a 640 X 480 screen, 0 is the very left edge, while 480 the very right one.
For y coordinates, they starts from up istead, and increase from 0 to screen height.
So, 0,0 is the upper left corner of the screen; 640,0 is the upper right corner; 0,480 is the lower left corner, while 640,480 is the very lower right corner:
0,0 . . . . . . . . 640,0
.
.
.
0,480 . . . . . . . 640,480
So, if you want to move an astroship on the screen, and you want to move from left to right, you have to increase the ship's x coordinates; while if you want to move the ship up, you have to decrease its y coordinates.
Hope this helps,
Sergio.