Some question about graphics.library lowlevels

Hello!

I tried to ask these question at utilitybase.com, however noone knows the answer there. I hope this is the better place to ask them, i see there are some oldschool demo coders here with lowlevel stuff knowledge. Perhaps someone knows answers...

1. What is actually DrawInfo.dri_Resolution? In what units is it expressed? Comment in OS3.9 NDK says that is's a copy of DisplayInfo data for screen's display mode.
I guess it's taken from DisplayInfo.Resolution. Well, again, what is it? Comment is short: "ticks-per-pixel X/Y". What is tick then?

2. About sprites, when used by graphics.library. If i want to completely remove my sprite from the screen, before FreeSprite() or FreeSpriteData(), what should i do? I beleive if i just call FreeSpriteData() the hardware will still be directed to display deallocated sprite image, which will then be trashed? So what function does the job of actual sprite removal? FreeSprite() FreeSpriteData()? Should i do it manually somehow?

I am working graphics.library on AROS operating system and i am implementing some missing parts. The answers are needed in order to do this correctly.

[Toni Wilen]

"tick": http://eab.abime.net/showthread.php?t=53132

Thanks. This little investigation gives me some ideas.
I also know that this information is used by BOOPSI gadgets to render themselves. I guess relation of these two numbers shows how square the pixel is.

[Photon]

Originally Posted by Sonic

2. About sprites, when used by graphics.library. If i want to completely remove my sprite from the screen, before FreeSprite() or FreeSpriteData(), what should i do? I beleive if i just call FreeSpriteData() the hardware will still be directed to display deallocated sprite image, which will then be trashed? So what function does the job of actual sprite removal? FreeSprite() FreeSpriteData()? Should i do it manually somehow?

Define "actual sprite removal"...

FreeSprite frees 1 of the 8 hardware sprites that you reserved for use with GetSprite for your Viewport; returns it to be used by the OS (or another program that needs to use a sprite).

FreeSpriteData should free the memory containing the sprite structure data - sprite's pixeldata etc.

So I guess you GetSpriteData and copy spritegraphics into it at your program init, then when you need to move them around or show them you ask the OS to use some sprites with GetSprite; when they don't need to be seen anymore you FreeSprite and when you don't need the spritegraphics anymore you FreeSpriteData. Don't take my word as the law; no manuals here where I am.

Do you have a manual like Libraries & Devices and an Amiga setup where you can try out how things are meant to work? Then you would get a good feel of what differs between sprites and Vsprites, blitlists with bobs etc., and get to know some of the hard-to-know-without-using details of some functions (like er, I dunno, that FileInfo-structs have to be 8-byte-aligned).

Amiga is special in that its OS is more closely adapted to how the hardware works than other OSes (less abstracted from hw). For example, I would guess that by modifying the SpriteData, you can actually re-use the GetSprite "sprite channel 0-7" just as you do with hardware programming; if that's true and you don't support it because you think sprites are "normal sprite" implementations, then programs using that feature will not work.