Making ULA screen transparent

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Ljg701
Posts: 5
Joined: Sun Jan 13, 2019 1:50 pm

Making ULA screen transparent

Post by Ljg701 » Sat Mar 02, 2019 3:16 pm

Hello,

I'd like to make the ULA screen transparent so that except for high score text, the layer 2 content can be seen below it. what do I need to do to the ULA data?

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varmfskii
Posts: 186
Joined: Fri Jun 23, 2017 1:13 pm
Location: Albuquerque, NM USA

Re: Making ULA screen transparent

Post by varmfskii » Sat Mar 02, 2019 5:54 pm

you need to make the paper color you are using the current transparency color. The simplest way to do this is to set the default paper color (dim white) to $e3 (8-bit colour). To do this:
nextreg $43,$80
;; select ULA primary palette for changes (no auto-increment)
;; primary palette active for ULA, Layer 2, and Sprites
;; ULANext disabled
nextreg $40,$17
;; select palette index 23 (paper index 7)
nextreg $41,$e3
;; set palette value to $e3 (default transparency colour).

In addition you need to make sure that the layer 2 graphics are active and ULA is on top of Layer 2.
Backer #2741 - TS2068, Byte, ZX Evolution

Ljg701
Posts: 5
Joined: Sun Jan 13, 2019 1:50 pm

Re: Making ULA screen transparent

Post by Ljg701 » Mon Mar 04, 2019 10:43 pm

thank you!

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