Sprite Expansion Library 2.0 (LowRes NX)

nathanielbabiak 2021-01-06 04:49 (Edited)

Sprite Expansion Library

This library will display filled polygons much faster than my other three full-screen display systems. It's blazing fast compared to the Pxl Library! And, if your game doesn't ultimately use all eleven of the allocated sprites, the raster interrupt subprogram can be trimmed down to gain even more speed!

The technique works per row (raster scanline). It uses sprites N=0 to N=10 to display horizontal lines on the screen. (You can adjust the LowRes NX sprite numbers in SUB S_RASTER.) Each sprite can be from 1 to 32 pixels wide, so to cover a whole row (of 160 pixels) it would use five sprites (5*32=160). A single scanline can be modified individually (it doesn't need to modify the surrounding rows above and below).

S_CLS clears the whole screen of all lines, and S_PXL draws a single pixel of a specific palette and color.

S_HORZ draws a single horizontal line. It uses 1 to 5 sprites starting with sprite N. It uses as many sprites as required to draw the whole line. The other drawing commands call S_HORZ.

A few notes:

Because of the nature of the technique, pixel-perfect collision testing with HIT or other methods is not possible without also being extremely slow.
This update automatically tracks the sprite numbers used. If you want your game to track the sprite numbers used instead, see the comments in S_INIT and S_NEXT.
This update uses direct-draw. If you want to use a double-buffer page-flip instead, see the comments in S_INIT.

Release

Sprite Expansion Library 2.0