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AuthorTopic: BlitzBasic2 and interlace mode  (Read 369 times)

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Offline Tymo500

BlitzBasic2 and interlace mode
« on: October 13, 2021, 03:02:42 AM »
Hi need little help only with one command

InitCopList 0,$114

It does not give Interlace mode.
It isa in BLITZ mode and working on BitMap mode. I have not access to interlace yet.

Interlace works very fine in Amiga mode and After command: Screen 0,28,"title"
Loads ILBM IFF very well even Hires & Interlace 640x400

If somebody knows how to achive thid interlace mode with hires in BLITZ mode.
I am programmer basic/assembler.
Manual is very poor about this. :(
 

Offline Pat the Cat

Re: BlitzBasic2 and interlace mode
« Reply #1 on: October 14, 2021, 03:35:54 AM »
Using copper to get interlace is involved, consult Hardware Reference Manual.

Using Blitz 2 to open an Intuition screen in interlace is pretty easy as per page 173;-

https://ia801009.us.archive.org/33/items/bb21manual/BB21Manual.pdf

EDIT: The problem with interlace is that the start address of each bitplane has to be changed after each raster frame.

On a non-interlaced screen, the data read position is just reset back to the start address at the end of each frame.

This is no good for interlace, first the even frame is displayed, and the next video frame, the odd lines are displayed.

This makes for a convoluted copper list, having to change the bitplane start position on each frame.

Hey, you wanted total control in assembler. You got it. :)
« Last Edit: October 14, 2021, 04:17:39 AM by Pat the Cat »
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