Treasure of Tarmin Graphics - How'd They Do That?

[First Spear]

For anyone who has dug into the ToT code, are the monsters and items MOBs or cleverly-positioned background tiles swapped in and out?

 

 

 

Thanks.

[+Rick Reynolds]

I haven't looked at the code at all, but after playing Tarmin for the podcast I assumed the enemies and items in the playfield were MOBs (aka sprites), while the inventory and stats area was all done with background tiles.

[+Rick Reynolds]

Oops, I forgot to mention that the Intellivision can do 2x, 4x, or 8x multipliers (stretching) in the Y direction and 2x in the X direction. That's how the monsters were made to be tall on the screen (I believe).

[First Spear]

The perspective thing makes sense, stretching to give a sense of distance. But the detail still seems higher than that I'd expect from an 8x8 MOB. I am wondering if there is a pattern of "MOB stacking" that goes on to give the monsters their level of detail.

 

Thanks.

 

Oops, I forgot to mention that the Intellivision can do 2x, 4x, or 8x multipliers (stretching) in the Y direction and 2x in the X direction. That's how the monsters were made to be tall on the screen (I believe).

[+Tarzilla]

They aren't 8x8. Each character appears to be comprised of two 8 wide x16 high stretched at lease by two horizontal and vertical and put side by side, left and right side.

 

The above picture has too much jpg compression artifacts and was sized up by a paint program that did not double the pixels without anti aliasing.

[freewheel]

I've spent a LOT of time duplicating some of the things they did back in the day, to figure this stuff out. As well as trying to clone more recent and complex sprites.

 

That screenshot is very telling, if you know how to count INTV pixels (even with the sub-optimal quality). The purple guy is 2 MOBs, each of which are 2 GRAM cards stacked on top of each other. It's 2 8x16 MOBs like Tarzilla says, with a lot of stretching. What you refer to as "MOB stacking" is just a flag in the STIC - bit 7 in the Y register, otherwise known as "YRES". It will take whatever GRAM card you point to and insert the next addressed card directly below it. Here's the relevant text from the IntyBASIC manual:

 

Y contains coordinate Y (0-95)
bit 7 = Draw 16-line sprite. (it should be aligned in even GRAM boundary 0/2/4/8 etc)
bits 9-8 = Scale 00= 0.5x, 01= 1x, 10= 2x, 11= 4x

 

Given everything else in that shot, it's *possible* that it was all done with BACKTAB cards but I doubt it. That would be a lot of work with very little benefit (unless there's something else that happens in the gameplay that I'm not taking into account - I rarely play the D&D games to be honest).

[intvnut]

I've spent a LOT of time duplicating some of the things they did back in the day, to figure this stuff out. As well as trying to clone more recent and complex sprites.

 

That screenshot is very telling, if you know how to count INTV pixels (even with the sub-optimal quality). The purple guy is 2 MOBs, each of which are 2 GRAM cards stacked on top of each other. It's 2 8x16 MOBs like Tarzilla says, with a lot of stretching. What you refer to as "MOB stacking" is just a flag in the STIC - bit 7 in the Y register, otherwise known as "YRES". It will take whatever GRAM card you point to and insert the next addressed card directly below it. Here's the relevant text from the IntyBASIC manual:

 

 

The Minotaur only has 16 unique rows, so it's two GRAM cards. However, it's a single 8x16 MOB. MOBs set to 8x16 take two GRAM cards.)

 

But yeah, all the bad guys and objects are drawn with MOBs.

 

Fun trick to expose the MOB-i-ness of the enemies and objects: Walk around the outer corridor and stop in front of one of the "maze entrance medallions" on the floor. Then, glance left (or right) toward the maze. If there's an enemy or object behind the entrance, the medallion will sometimes 'glitch' to reveal what that object is.

 

This happens with other objects too. The medallion is an easy one to experiment with, though, as there are no other objects or enemies in the outer corridor, except the occasional gate that takes you between mazes.

[freewheel]

The Minotaur only has 16 unique rows, so it's two GRAM cards. However, it's a single 8x16 MOB. MOBs set to 8x16 take two GRAM cards.)

 

But it's 16 columns wide. It looks to me like 2 MOBs side-by-side, each of which are 8x16 MOBs. 4 cards in total.

[intvnut]

 

But it's 16 columns wide. It looks to me like 2 MOBs side-by-side, each of which are 8x16 MOBs. 4 cards in total.

 

Oh I see. Yes, I went back and looked that the horizontal count, and you're correct. I was breezing through this too quickly.

[freewheel]

 

Oh I see. Yes, I went back and looked that the horizontal count, and you're correct. I was breezing through this too quickly.

 

You can see that I do this way too often. It's like reading the Matrix at this point... blonde.. brunette...

 

I also noticed that this is one of the rare times when they end up with "tall pixels". It's much more common to see the "wide pixels" like for the Running Man. A single 8x16 MOB horizontally stretched. This is a 16x16 MOB vertically stretched. It seems to be used a lot less often - but an impressive sprite size for the era.

[intvnut]

 

You can see that I do this way too often. It's like reading the Matrix at this point... blonde.. brunette...

 

I also noticed that this is one of the rare times when they end up with "tall pixels". It's much more common to see the "wide pixels" like for the Running Man. A single 8x16 MOB horizontally stretched. This is a 16x16 MOB vertically stretched. It seems to be used a lot less often - but an impressive sprite size for the era.

 

 

I know the feeling. I'm usually better about counting pixels. The tall, skinny pixels threw me off, most likely. That, and I really truly only focused on the height and not the width.

 

I get that "in the Matrix" feeling myself. With LTO Flash! I've found myself reading transaction logs directly in hex almost more easily than English. That seems to have temporarily displaced my pixel-counter.