Code Addendum 01 - gforth: OpenGL Graphics Lesson 01
Tim Trussell
\ gforth: OpenGL Graphics Lesson 01
\ ===================================================================
\ File: opengl-lesson01.fs
\ Author: Jeff Molofee
\ Linux Version: Ti Leggett
\ gForth Version: Timothy Trussell, 07/06/2010
\ Description: Setting up an OpenGL window
\ Forth System: gforth-0.7.0
\ Linux System: Ubuntu v10.04 LTS i386, kernel 2.6.31-23
\ C++ Compiler: gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5)
\ ===================================================================
\ NeHe Productions
\ http://nehe.gamedev.net/
\ ===================================================================
\ OpenGL Tutorial Lesson 01 BaseCode
\ ===================================================================
\ This code was created by Jeff Molofee '99
\ (ported to Linux/SDL by Ti Leggett '01)
\ Visit Jeff at http://nehe.gamedev.net/
\ ===================================================================
\ ---[ Marker ]------------------------------------------------------
\ Allows for easy removal of a previous loading of the program, for
\ re-compilation of changes.
\ If ---marker--- exists, execute it to restore the dictionary.
[IFDEF] ---marker---
---marker---
[ENDIF]
\ ---[ New Marker ]--------------------------------------------------
\ Set a marker point in the dictionary.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ If/when the program is re-loaded, everything in the dictionary
\ after this point will be unlinked (removed). Essentially 'forget'.
\ Does NOT affect linked libcc code, however.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ Some programmers prefer to exit/re-enter gforth to ensure that they
\ are starting with a clean slate each time. Your choice.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
marker ---marker---
\ ---[ Set Number Base ]---------------------------------------------
\ Set the numeric system to base 10
decimal
\ ---[ Prototype Listing ]-------------------------------------------
\ : zprint { *str -- }
\ : zstring ( *str len -- *str )
\ : SF, ( r -- )
\ : Initialize-SDL ( -- )
\ : Get-Video-Info ( -- )
\ : Compile-Video-Flags ( -- )
\ : Check-HW-Surfaces ( -- )
\ : Check-HW-Blits ( -- )
\ : Init-Double-Buffering ( -- )
\ : Init-Video ( -- )
\ : Init-Caption ( -- )
\ : ResizeWindow { _width _height -- boolean }
\ : Help-Msg ( -- )
\ : lesson01 ( -- )
\ ------------------------------------------------[End Prototypes]---
cr cr .( Loading Tutorial...) cr
\ ---[ opengl-exit-flag ]--------------------------------------------
\ Boolean flag set by HandleKeyPress if the ESC key is pressed.
\ Will be used in a begin..while..repeat loop in the main function.
FALSE value opengl-exit-flag
\ ---[ screen ]------------------------------------------------------
\ Pointer for working SDL surface
0 value screen
\ ---[ Screen Dimensions ]-------------------------------------------
\ These specify the size/depth of the SDL display surface
640 constant screen-width
480 constant screen-height
16 constant screen-bpp
\ ===[ Ancilliary Support Routines ]=================================
\ These are support routines that help with the normal programming.
\ ---[ zprint ]------------------------------------------------------
\ Displays a zero-terminated string
: zprint { *str -- }
begin
*str C@ 0<>
while
*str C@ emit
*str 1+ to *str
repeat
;
\ ---[ zstring ]-----------------------------------------------------
\ Most SDL and OpenGL functions that require string data also require
\ that those strings be in a zero-delimited format. The Forth method
\ of passing strings is to pass the address followed by the length of
\ the string to the stack.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ To convert a Forth string to a zero-delimited string requires that
\ we add a character to the Forth string (at the end) which is then
\ passed to the zstring function, which changes that character to a
\ NULL (0) value, and drops the length parameter from the stack.
\ I add the character "0" to the end, since it signifies visually the
\ additional character that is to be converted.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ Example:
\ s" data/my_funky_picture.bmp" Load-Picture
\ becomes
\ s" data/my_funky_picture.bmp0" zstring Load-Picture
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
: zstring ( *str len -- *str ) over + 1- 0 swap C! ;
\ ---[ SF, ]---------------------------------------------------------
\ Allocate and store a short float - 4 bytes - to the dictionary.
\ Suggested by Anton Ertl 06/03/2010 - Thanks Anton!
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ <here> returns the address of the next free dictionary byte
\ <1 sfloats> calculates the size of an sfloat variable - 4 bytes
\ <allot> allocates space at the next free dictionary address
\ <SF!> stores the floating point value at the address <here>,
\ which is already on the stack.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
: SF, ( r -- ) here 1 sfloats allot SF! ;
\ ===[ Load Graphics Framework ]=====================================
\ This loads the opengllib-1.xx.fs file, which contains all of the
\ OpenGL scene generation code functions.
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
\ -- Loads the OpenGL and SDL libcc interface dependancy files
\ -- Loads the high-level OpenGL code
\ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
require opengllib-1.01.fs
\ ===[ gforth BaseCode ]=============================================
\ The following functions are "common" to all of the tutorials, and
\ comprise the basic framework for all of the tutorials in the series
0 value videoflags \ pointer to video hardware info array
0 value isActive \ "focus" indicator for the mouse
0 value VideoInfo \ pointer to video mode data
\ Create an event structure for accessing the SDL Event subsystems
create event here sdl-event% nip dup allot 0 fill
\ Initialize the SDL Video subsystem
: Initialize-SDL ( -- )
SDL_INIT_EVERYTHING sdl-init 0< if
cr ." Video Initialization failed: "
sdl-geterror zprint cr
bye
then
;
\ Load information about the video hardware in the computer
: Get-Video-Info ( -- )
sdl-getvideoinfo dup to VideoInfo 0= if
cr ." Video query failed: " sdl-geterror zprint cr
bye
then
;
\ Build a flag variable specifying the video characteristics to set
: Compile-Video-Flags ( -- )
SDL_OPENGL \ enable OpenGL in SDL
SDL_GL_DOUBLEBUFFER OR \ Enable double buffering
SDL_HWPALETTE OR \ Store the palette in hardware
SDL_RESIZABLE OR \ Enable window resizing
to videoflags \ save the flags
;
\ Add flag for if hardware surfaces can be created
: Check-HW-Surfaces ( -- )
VideoInfo sdl-video-info-hw-available @ 0<> if
SDL_HWSURFACE
else
SDL_SWSURFACE
then
videoflags OR to videoflags
;
\ Add flag for if hardware-to-hardware blits are available
: Check-HW-Blits ( -- )
VideoInfo sdl-video-info-blit-hw @ 0<> if
videoflags SDL_HWACCEL OR to videoflags
then
;
\ Enable double buffering
: Init-Double-Buffering ( -- )
SDL_GL_DOUBLEBUFFER 1 sdl-gl-set-attribute
;
\ Create an SDL surface and open the display window
: Init-Video ( -- )
screen-width screen-height screen-bpp videoflags sdl-set-video-mode
dup 0= if \ verify a surface was created
drop \ window not created, error out
cr ." Video mode set failed: " sdl-geterror zprint cr
bye \ exit to terminal window
then
to screen \ save to surface pointer
;
\ Put a title onto the window caption bar
: Init-Caption ( -- )
s" gforth/OpenGL: NeHe Lesson 10" zstring NULL sdl-wm-set-caption
;
\ Reset our viewport after a window resize
: ResizeWindow { _width _height -- boolean }
_height 0= if \ protect from divide by zero
1 to _height
then
\ set up the viewport
0 0 _width _height gl-viewport
\ Change to the projection matrix and set our viewing volume
GL_PROJECTION gl-matrix-mode
\ Reset the matrix
gl-load-identity
\ Set our perspective - the F/ calcs the aspect ratio of w/h
45e _width S>F _height S>F F/ 0.1e 100e glu-perspective
\ Make sure we are changing the model view and not the projection
GL_MODELVIEW gl-matrix-mode
\ Reset the matrix
gl-load-identity
\ Return a good value
TRUE
;
\ Display keyboard/mouse help information
: Help-Msg ( -- )
page
0 \ init line count
." Keyboard Functions:" 1+
cr ." ESC - exits program" 1+
cr ." F1 - toggles fullscreen/windowed screen" 1+
cr 1+
cr ." Mouse Functions:" 1+
cr ." Move off window to pause demo" 1+
cr ." Move onto window to resume demo" 1+
cr ." Resize window by dragging frame" 1+
cr ." Minimize/Maximize/Exit with window buttons" 1+
cr 1+
to fps-line \ where to display the fps at
;
: lesson01 ( -- )
Initialize-SDL \ Init the SDL subsystem
Get-Video-Info \ Get the video info from SDL
Compile-Video-Flags \ Compile the flags to pass to
SDL_SetVideoMode
Check-HW-Surfaces \ Check if surfaces can be stored in memory
Check-HW-Blits \ Check if hardware blits can be done
Init-Double-Buffering \ Set up OpenGL double buffering
Init-Video \ create SDL surface; open window
Init-Caption \ set the window title
caption
InitGL FALSE = if \ initialize OpenGL
sdl-quit \ on error, close down and exit
cr ." Could not initialize OpenGL." cr
bye
then
screen-width screen-height ResizeWindow drop \ resize the window
Reset-FPS-Counter \ initialize the counter with sdl-get-ticks
Help-Msg \ display the keyboard function info
begin \ wait for events
opengl-exit-flag 0= \ repeat until this flag set TRUE
while
begin
event sdl-pollevent \ are there any pending events?
while
event sdl-event-type c@ \ yes, process the events
case
SDL_ACTIVEEVENT of \ application visibility event occurred
event sdl-active-event-gain C@ if
TRUE \ gained focus - draw in window again
else
FALSE \ lost focus - stop drawing in window
then
to isActive
endof
SDL_VIDEORESIZE of \ window resize event occurred
event sdl-resize-event-width @ \ get new width
event sdl-resize-event-height @ \ get new height
screen-bpp \ use current bpp
videoflags \ get flags
sdl-set-video-mode \ attempt to create a new window
dup 0= if \ error out if not successful
drop
sdl-quit
cr ." Could not get a surface after resize: "
sdl-geterror zprint cr
bye
then
to screen \ success! save new pointer
event sdl-resize-event-width @
event sdl-resize-event-height @
ResizeWindow drop \ calculate new perspective
endof
SDL_KEYDOWN of \ key press event occurred
event HandleKeyPress
endof
SDL_QUIT of \ window close box clicked, or ALT-F4 pressed
TRUE to opengl-exit-flag
endof
endcase
repeat \ until no more events are in the queue
isActive if \ if we have mouse focus, draw the scene
DrawGLScene drop
then
repeat \ until opengl-exit-flag is set to TRUE
Shutdown \ close down the SDL systems gracefully
TRUE to isActive \ reset for next program run
;
cr .( gforth/OpenGL: NeHe Lesson 1)
cr .( type "lesson01" to execute) cr
rickman
> \ ===[ Code Addendum 01
Did you really need to make 13 posts? Couldn't you put the code on a
web site and let people download it?
Rick
Timothy Trussell
Perhaps you did not read the first post of this Lesson, where I put in
the beginning of the text the following statement:
---[ Information ]---------------------------------------------------
This column will be posted to the Taygeta Forth Achive site:
ftp://ftp.taygeta.com/pub/Forth/Archive/tutorials/gforth-sdl-opengl/
in the file:
opengl-lesson01.zip
along with all required source files.
It may take a little time for the files to be moved to the above
directory, so keep checking until they have been placed there.
--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
The archive of this posting will become available, when it has been
transferred to the above directory from their incoming section.
I do not have a web site of my own, on which to post these.
I am also in process of trying to get the archives posted to the
original NeHe Tutorial page, where the other conversions of the Lesson
Tutorial code has been placed.
Tim-
--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---
rickman
post the link where they could be found on the web and leave it at
that...
Rick
> --- news://freenews.netfront.net/ - complaints: n...@netfront.net ---
limdi...@gmail.com
jo...@planet.nl
Thanks to his multiple posts I could find his sources and port them to
Win32Forth. (24x by now in one big program.)
Thank you Timothy !
Jos
Steve
j...@planet.nl wrote:
> I am glad he did.
> Thanks to his multiple posts I could find his sources and port them to
> Win32Forth. (24x by now in one big program.)
> Thank you Timothy !
> Jos
>