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vgi_fast | ||
vgi_original | ||
vgi_slow | ||
benchmark_fast.s | ||
benchmark_original.s | ||
benchmark_slow.s | ||
clock.vgi | ||
color_test.s | ||
fireplace.vgi | ||
hardware.inc | ||
hello.bas | ||
make_color_test.c | ||
make_vgi_asm.c | ||
Makefile | ||
myst_book.vgi | ||
new.vgi | ||
path.vgi | ||
README.VGI | ||
red_book.vgi | ||
rocket_door.vgi | ||
rocket.vgi | ||
test_vgi.s | ||
zp.inc |
VGI -- VMW Retro Vector Graphics Interface This was designed mostly as a proof-of-concept to drawing some Myst scenes. Might not work well for general graphics. The Apple II Hi-res screen is 280x192 and 6 colors with lots of limitations that are a bit complex to get into here. Some of the limitations in the interface here are working around Apple II issues. Apple II Hi-res Colors: ~~~~~~~~~~~~~~~~~~~~~~~ 0 = black (for purple/green) 1 = green 2 = purple 3 = white (for purple/green) 4 = black (for blue/orange) 5 = orange 6 = blue 7 = white (for blue/orange) Note Apple II uses NTSC artifact colors, so weird things happens when you try to put colors next to each other: + Colors need to be two pixels wide, if you draw single width they may not appear depending on even/odd column + White lines drawn single width will be colored instead + Two colors of same group next to each other will have white or black border between + Two colors of different group next to each other will have odd effects as can only change group every 3.5 pixels. The VGI Commands ~~~~~~~~~~~~~~~~ =================== VGI Clearscreen (0) CLS color clears screen using ROM routine using color ================= VGI Rectangle (1) RECT color1 color2 x1 y1 x2 y2 draw filled rectangle from (x1,y1) to (x2,y2) color1 and color2 are drawn as alternating colors (horizontal stripes) x1 must be < 255. relative drawing is used so x2 can go to the edge of the screen (279) Unlike the other routines, this one uses custon horizontal-line routines for speed so much faster than the ROM line routine ============== VGI Circle (2) CIRC color cx cy r Draw a circle of color with center (cx,cy) and radius r Circles with radius 0 will give an interesting non-circle effect. Bresenham circles are drawn and so certain sizes don't look the best. Also if the radius is too big things might break as the 8-bit unsigned int oveflows ===================== VGI Filled Circle (3) FCIRC color cx cy r Draw a filled circle of color at location (cx,cy) with radius r ============= VGI Point (4) POINT color x y Draws a point of color at (x,y) Note, X can be up to 279 here (the color is overloaded behind the scenes to support this) The last point you draw is the starting point for LINETO ============== VGI Lineto (5) LINETO x y Draws a line to (x,y). The starting point and color come from the last POINT command. Note X cannot be > 255 so it can be trouble drawing at the right edge of the screen. POINT can go up to 279, so you might be able to get what you want by drawing from right to left ========================== VGI Dithered Rectangle (6) DRECT c1 c2 x1 y1 x2 y2 Draws a rectangle, but this time the two colors are raw bitmaps for the output colors, not one of the Apple II colors. This lets you do fancier dithered color patterns, but it's really hard getting dither patterns that look nice. ========================= VGI Vertical Triangle (7) VTRI color vx vy xl xr yb VTRISK color vx vy xl xr yb skip Draw a flat bottom filled triangle of color. The top vertex is at (vx,vy) The bottom goes from (xl,yb) to (xr,yb) If your triangle is too tall you might get moire effects. This was much simpler than a proper filled triangle routine. The skip variant adds SKIP as an X increment instead of 1 In memoy the skip is encoded in the high nibble of color =========================== VGI Horizontal Triangle (8) HTRI color vx vy yt yb xr Draw a flat-sided filled triangle of color. The side vertex is at (vx,vy) The opposite side goes from (xr,yt) to (xr,yb) ================================== VGI Vertical Striped Rectangle (9) VSTRP c1 c2 x1 y1 x2 y2 Draws a rectangle, but this time the two colors are raw bitmaps for the output colors, but to use even/odd columns. On apple II this allows repeating pattern, but since it's a multiple of 7 you can't get true stripes (for that we'd need a 4-byte repeating pattern) ============= VGI Line (10) LINE color x1 y1 x2 y2 Draws a line from (x1,y1) Note, X1 can be up to 279 here (the color is overloaded behind the scenes to support this) The last point you draw is the starting point for LINETO ============= VGI Line Far (11) LINE color x1 y1 x2 y2 Draws a line from (x1,y1) In this one X2 must be > 255 ============ VGI End (15) END this tells the drawing routine that we are done ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Size comparison: VGI data Captured+Compressed compressed autoconvert ======== =================== ====================== clock 385B 1228B rocket 623B door 189B book 212B firep 486B