The Sprite Stuff (using sprites on ColecoVision)

[Jess Ragan]

I've finally advanced to sprites on the ColecoVision, and noticed something peculiar. If you stack one sprite on top of another to add color and detail to it, it will flicker ever so slightly as the two sprites struggle for dominance. I thought it was because I was putting the sprite drawing commands inside an infinite loop, but no, even using the command once still resulted in flicker.

 

Evidently, you can't overlay sprites without the two of them fighting over which one displays, even if you're just using two sprites. It explains why when they drew Mario on Donkey Kong, they only had ALL red pixels, ALL blue pixels, and ALL white pixels in each of his three sprites, with none of the pixels from different colors touching.

[+nanochess]

Technically the TMS9928 Video Processor has sprites with different priority. However, this isn't very useful in games with many sprites at the same time.

 

In the most recent CVBasic compiler, the sprite routine does flickering so all sprites are visible (although alternating video frames). This means that you cannot depend on a sprite covering another, so for multicolor sprites you need to separate the pixels with different colors so no pixel overlays another.

 

A trick I used in Zombie Near where the player has a suit color and a face color, is having the face sprite with the face defined in the bottom part of the sprite, this way the face doesn't overlay the body, and doesn't count against the limit of 4 sprites in the same line.

[AnalogKid]

On 4/13/2024 at 10:29 PM, Jess Ragan said:

I've finally advanced to sprites on the ColecoVision, and noticed something peculiar. If you stack one sprite on top of another to add color and detail to it, it will flicker ever so slightly as the two sprites struggle for dominance. I thought it was because I was putting the sprite drawing commands inside an infinite loop, but no, even using the command once still resulted in flicker.

 

Evidently, you can't overlay sprites without the two of them fighting over which one displays, even if you're just using two sprites. It explains why when they drew Mario on Donkey Kong, they only had ALL red pixels, ALL blue pixels, and ALL white pixels in each of his three sprites, with none of the pixels from different colors touching.

Also if you design multi-color sprites such that the pixels collide then you're going to be always triggering the collision detection VDP register effectively rendering it useless.

[Kiwi]

There's 4 sprites on a line limitation.  Reordering the sprites in the sprite attribute is a good option instead having the 5th sprite dropping out completely.