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Re: CGA Graphics library

in Milliways
And I don't see how one can move down a column instead of across a row without incurring additional costs due to the odd/even layout of screen lines in CGA memory. At least for this problem, we have a solution. This can be done as in my code above. Calculate whether the first line of the sprite is …

Re: CGA Graphics library

in Milliways
So, this algorithm is a good starting point. Although it can be slightly improved, since we have one free register. But it has some drawback. It outputs a sprite that is a multiple of a byte, not a pixel. I don't think we should convert bytes representation to pixels, but we should add another …

Re: CGA Graphics library

in Milliways
Dear wbhart ! Thanks for your reply. We can't do without a shift anyway, since we want to output positions that are not multiples of four. I developed the subroutine that I roughly wanted. And it can be a starting point for learning. Also I will certainly be very happy with your additions and …

Re: CGA Graphics library

in Milliways
We can make it even easier: If the first line is odd, GOTO 1$ 0$: Draw an even line If there are no more lines, exit Switch to the next odd line 1$: Draw an odd line If there are no more lines, exit Switch to the next even line GOTO 0$ This is a fast and good algorithm. This way, there is really no …

Re: CGA Graphics library

in Milliways
I came up with two tricks for the analog of "putimage" subroutine: 1. In the game Battle City for CGA, I saw a subroutine that is approximately similar to what I need. But that subroutine uses an internal buffer for bit-shifting the line. http://www.balagurov.com/software/tank How to do without a …

Re: CGA Graphics library

in Milliways
Dear wbhart, I'm very impressed with your achievements at the quick drawing of pixel graphic and sprites, especially clipping off the outside of the screen! Especially on such a slow machine. And I thought: wbhart is the person who can only help me. I want to port the game from ZX Spectrum to DOS/ …

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