djh@neuromancer.metaphor.com (Dallas J. Hodgson) (02/12/91)
Well, I've been working on a project that uses a custom Copper display to display two viewports the hard way. The top screen is some 184 lines high the bottom about 15 lines. Here's the question: I can clip any sprites in the top screen to its boundaries by adjusting the VSTOP position of its sprites appropriately. The tough question is, How can I scroll a sprite up and off the TOP part of the screen so it will gradually disappear? Adjusting VSTART of the sprite will allow it to scroll off 20 pixels or so, then it disappears completely. I could adjust the sprxpth ptrs to somewhere in the middle of the sprite, (effectively truncating its top part accordingly) but I'd have to counter the effect of the bogus posctl data that would get read in. I've got some tricky ideas on this, but I'd rather know how it's REALLY done! P.S. VSprites used accomplish this trick just fine, but I'm not using 'em anymore. -- +----------------------------------------------------------------------------+ | Dallas J. Hodgson | "This here's the wattle, | | Metaphor Computer Systems | It's the emblem of our land. | | Mountain View, Ca. | You can put it in a bottle, | | USENET : djh@metaphor.com | You can hold it in your hand." | +============================================================================+ | "The views I express are my own, and not necessarily those of my employer" | +----------------------------------------------------------------------------+