Code Addendum 01 - gforth/SDL 16-bpp Pixel Demo
Tim Trussell
\ gforth/SDL 16-bpp Pixel Demo
\ ===================================================================
\ File Name: sdl-16bpp.fs
\ Author: Timothy Trussell
\ Date: 04/05/2010
\ Description: SDL 16-bpp demo
\ Forth System: gforth-0.7.0
\ Linux System: Ubuntu v9.10 i386, kernel 2.6.31-20
\ C++ Compiler: gcc (Ubuntu 4.4.1-4ubuntu9) 4.4.1
\ ===================================================================
\ From the Linux Journal 4401.tgz
\ ===================================================================
page .( ---[ Loading SDL 16-bpp Demo ]---) cr
[IFDEF] ---marker---
---marker---
[ENDIF]
marker ---marker---
decimal
require sdllib.fs
0 value demo-raw-pixels
0 value demo-pixel-color
0 value demo-offset
\ ---[ Create-16bpp-Pixel ]------------------------------------------
\ Maps the passed r/g/b components to the desired 16-bpp value
: Map-Pixel { *dst _r _g _b -- n }
*dst sdl-surface-format @ _r _g _b sdl-map-rgb
;
: demo16 ( -- )
1024x768x16 s" SDL 16-bpp Demo0" InitGraph \ init display
screen-surface sdl-mustlock if \ Lock the surface if required
screen-surface sdl-locksurface drop
then
screen-surface sdl-surface-pixels @ to demo-raw-pixels \ save ptr
\ We can now safely write to the video surface. We'll draw a nice
\ gradient pattern by varying our red and blue components along
\ the X and Y axes.
window-screenh 0 do
window-screenw 0 do
screen-surface j 0 i Map-Pixel to demo-pixel-color
\ Calculate the memory offset of the pixel we wish to change
screen-surface sdl-surface-pitch sw@ j * i 2 * + to demo-offset
demo-pixel-color demo-raw-pixels demo-offset + w!
loop
loop
\ Now unlock the surface if required
screen-surface sdl-mustlock if
screen-surface sdl-unlocksurface
then
\ copy the buffer to the visible screen surface
screen-surface sdl-flip drop
\ ooohs and aaahs time...
10 to demo-offset \ set to whatever delay you want
cr ." Timer delay: "
demo-offset 0 do
demo-offset i - .
1000 sdl-delay
loop
0 .
CloseGraph
;
cr .( SDL-16bpp: demo16 ) cr