PRG Mbox Designer Manual 3.8 - Manual (Page 145)

MBOX ® MEDIA SERVER USER MANUAL 137
Step 14. After adding the opacity control press the Save button; then you can add the X and Y position controls.
Here's where you can speed things up by using copy and paste. Make sure that the opacity control is
highlighted in the listbox, press [
 C] and then [ V], and you'll get a copy of the opacity control. Rename it
"tX position."
a. For the Texture X position control, the universe is the same, the address is 2, the data type is "8-bit
127", stride is still 27. Two complex decisions remain though. For the control type; do you want to use
Texture X Pos or just X Position? And what should your scale value be? For this particular screen object
in this configuration (using projected mapping) you want to select "Texture X Pos" because you only
want to move the texture on the small square, not literally move the entire screen object on Mbox's
output screen. You don't actually need to move the square in the 2D view - if you imagine an LED
screen moving left and right on-stage, to keep projected mapping correct you only need to move the
texture in the opposite direction to the screen's movement. If the screen object were to move on-
screen, it could move away from the area that the LED processor is using for the LED screen.
Note: Why would you want to actually move the screen object? For your 3D representation (which will be covered
later), you want to see the actual square move on the screen to mimic the movement of the LED screen on-stage.
Also, if you were using this for a system with an actual projector instead of LED's, then you might need to move the
screen object as the piece of scenery is moved.
b. For the scale value, you want to be able to move the texture on this screen object so any part of the
applied 900 x 900 texture can be seen. Since the screen object is 300 x 300, this means you only ever
need to move the texture a maximum of 600 pixels in either direction (you may eventually want to set
min and max values, but not now). With an "8-bit 127" data format, its range being 127 counts in either
direction, you need to divide 600 pixels by 127 counts to get a scale of 4.72440945.
Regarding accuracy of scale values. The more accurate you can be with your scale/counts calculations, and
the more decimal places you use when entering those values, the more accurate the screen object's
responses to input will be. For linear movements, you should use at least 4 digits after the decimal point.
Step 15. Copy and paste the X Position control you just created, and rename it "tY Position." Change the address to
3, and the control type to Texture Y Pos. Press the Save button.
Note: Once you have one or more screen objects created in the editor, you'll want to test your configuration in Mbox
to make sure you have the correct sign on the scale value for your X and Y position properties. In most cases,
particularly with Art-Net-only control (i.e., no scenic encoders), once you figure out the signs for one screen object you
can use the same signing convention on all following screen objects. For this tutorial, leave the texture X position's
scale as positive, but make the texture Y position's scale negative.