I'm trying to develop some OpenGL programs that are cross platform friendly. Since they would need to run under both Linux and Windows (or whatever) using SDL seems to be the obvious choice.
I downloaded Lesson 17 (Linux/SDL code) from NeHe, and modified the headers slightly to accept a Win32 or Linux client. Here is the entire source code, the only changes having been made to the headers:
/* -- Include the precompiled libraries -- */
#ifdef WIN32
#pragma comment(lib, "SDL.lib")
#pragma comment(lib, "SDLmain.lib")
#pragma comment(lib, "SDL_image.lib")
#include <windows.h> // Header File For Windows
#include <stdio.h> // Header File For Standard Input/Output
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
#include <gl\glaux.h> // Header File For The Glaux Library
#else
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "SDL.h"
/* screen width, height, and bit depth */
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define SCREEN_BPP 16
/* Setup our booleans */
#define TRUE 1
#define FALSE 0
/* Number of textures to load */
#define NUM_TEXTURES 2
/* This is our SDL surface */
SDL_Surface *surface;
GLuint base; /* Base Display List For The Font */
GLuint texture[NUM_TEXTURES]; /* Storage For Our Font Texture */
GLuint loop; /* Generic Loop Variable */
GLfloat cnt1; /* Counter Used To Move Text & For Coloring */
GLfloat cnt2; /* Counter Used To Move Text & For Coloring */
/* function to recover memory form our list of characters */
GLvoid KillFont( GLvoid )
{
glDeleteLists( base, 256 ); /* Delete All 256 Display Lists */
return;
}
/* function to release/destroy our resources and restoring the old desktop */
void Quit( int returnCode )
{
/* Clean up our font list */
KillFont( );
/* Clean up our textures */
glDeleteTextures( NUM_TEXTURES, &texture[0] );
/* clean up the window */
SDL_Quit( );
/* and exit appropriately */
exit( returnCode );
}
/* function to load in bitmap as a GL texture */
int LoadGLTextures( )
{
/* Status indicator */
int Status = FALSE;
/* Create storage space for the texture */
SDL_Surface *TextureImage[2];
/* Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit */
if ( ( TextureImage[0] = SDL_LoadBMP( "data/font.bmp" ) ) &&
( TextureImage[1] = SDL_LoadBMP( "data/bumps.bmp" ) ) )
{
/* Set the status to true */
Status = TRUE;
/* Create The Texture */
glGenTextures( NUM_TEXTURES, &texture[0] );
/* Load in texture 1 */
/* Typical Texture Generation Using Data From The Bitmap */
glBindTexture( GL_TEXTURE_2D, texture[0] );
/* Generate The Texture */
glTexImage2D( GL_TEXTURE_2D, 0, 3, TextureImage[0]->w,
TextureImage[0]->h, 0, GL_BGRA_EXT,
GL_UNSIGNED_BYTE, TextureImage[0]->pixels );
/* Nearest Filtering */
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
/* Load in texture 2 */
/* Typical Texture Generation Using Data From The Bitmap */
glBindTexture( GL_TEXTURE_2D, texture[1] );
/* Linear Filtering */
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
/* Generate The Texture */
glTexImage2D( GL_TEXTURE_2D, 0, 3, TextureImage[1]->w,
TextureImage[1]->h, 0, GL_BGRA_EXT,
GL_UNSIGNED_BYTE, TextureImage[1]->pixels );
}
/* Free up any memory we may have used */
if ( TextureImage[0] )
SDL_FreeSurface( TextureImage[0] );
if ( TextureImage[1] )
SDL_FreeSurface( TextureImage[1] );
return Status;
}
/* function to build our font list */
GLvoid BuildFont( GLvoid )
{
GLuint loop; /* Loop variable */
float cx; /* Holds Our X Character Coord */
float cy; /* Holds Our Y Character Coord */
/* Creating 256 Display List */
base = glGenLists( 256 );
/* Select Our Font Texture */
glBindTexture( GL_TEXTURE_2D, texture[0] );
/* Loop Through All 256 Lists */
for ( loop = 0; loop < 256; loop++ )
{
/* NOTE:
* BMPs are stored with the top-leftmost pixel being the
* last byte and the bottom-rightmost pixel being the first
* byte. So an image that is displayed as
* 1 0
* 0 0
* is represented data-wise like
* 0 0
* 0 1
* And because SDL_LoadBMP loads the raw data without
* translating to how it is thought of when viewed we need
* to start at the bottom-right corner of the data and work
* backwards to get everything properly. So the below code has
* been modified to reflect this. Examine how this is done and
* how the original tutorial is done to grasp the differences.
*
* As a side note BMPs are also stored as BGR instead of RGB
* and that is why we load the texture using GL_BGR. It's
* bass-ackwards I know but whattaya gonna do?
*/
/* X Position Of Current Character */
cx = 1 - ( float )( loop % 16 ) / 16.0f;
/* Y Position Of Current Character */
cy = 1 - ( float )( loop / 16 ) / 16.0f;
/* Start Building A List */
glNewList( base + ( 255 - loop ), GL_COMPILE );
/* Use A Quad For Each Character */
glBegin( GL_QUADS );
/* Texture Coord (Bottom Left) */
glTexCoord2f( cx - 0.0625, cy );
/* Vertex Coord (Bottom Left) */
glVertex2i( 0, 0 );
/* Texture Coord (Bottom Right) */
glTexCoord2f( cx, cy );
/* Vertex Coord (Bottom Right) */
glVertex2i( 16, 0 );
/* Texture Coord (Top Right) */
glTexCoord2f( cx, cy - 0.0625f );
/* Vertex Coord (Top Right) */
glVertex2i( 16, 16 );
/* Texture Coord (Top Left) */
glTexCoord2f( cx - 0.0625f, cy - 0.0625f);
/* Vertex Coord (Top Left) */
glVertex2i( 0, 16 );
glEnd( );
/* Move To The Left Of The Character */
glTranslated( 10, 0, 0 );
glEndList( );
}
}
/* function to reset our viewport after a window resize */
int resizeWindow( int width, int height )
{
/* Height / width ration */
GLfloat ratio;
/* Protect against a divide by zero */
if ( height == 0 )
height = 1;
ratio = ( GLfloat )width / ( GLfloat )height;
/* Setup our viewport. */
glViewport( 0, 0, ( GLint )width, ( GLint )height );
/* change to the projection matrix and set our viewing volume. */
glMatrixMode( GL_PROJECTION );
glLoadIdentity( );
/* Set our perspective */
gluPerspective( 45.0f, ratio, 0.1f, 100.0f );
/* Make sure we're chaning the model view and not the projection */
glMatrixMode( GL_MODELVIEW );
/* Reset The View */
glLoadIdentity( );
return( TRUE );
}
/* function to handle key press events */
void handleKeyPress( SDL_keysym *keysym )
{
switch ( keysym->sym )
{
case SDLK_ESCAPE:
/* ESC key was pressed */
Quit( 0 );
break;
case SDLK_F1:
/* F1 key was pressed
* this toggles fullscreen mode
*/
SDL_WM_ToggleFullScreen( surface );
break;
default:
break;
}
return;
}
/* general OpenGL initialization function */
int initGL( GLvoid )
{
/* Load in the textures */
if ( !LoadGLTextures( ) )
return FALSE;
/* Build our font list */
BuildFont( );
/* Enable smooth shading */
glShadeModel( GL_SMOOTH );
/* Set the background black */
glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
/* Depth buffer setup */
glClearDepth( 1.0f );
/* The Type Of Depth Test To Do */
glDepthFunc( GL_LEQUAL );
/* Select The Type Of Blending */
glBlendFunc( GL_SRC_ALPHA, GL_ONE );
/* Enable 2D Texture Mapping */
glEnable( GL_TEXTURE_2D );
return( TRUE );
}
/* Function to print the string */
GLvoid glPrint( GLint x, GLint y, char *string, int set )
{
if ( set > 1 )
set = 1;
/* Select our texture */
glBindTexture( GL_TEXTURE_2D, texture[0] );
/* Disable depth testing */
glDisable( GL_DEPTH_TEST );
/* Select The Projection Matrix */
glMatrixMode( GL_PROJECTION );
/* Store The Projection Matrix */
glPushMatrix( );
/* Reset The Projection Matrix */
glLoadIdentity( );
/* Set Up An Ortho Screen */
glOrtho( 0, 640, 0, 480, -1, 1 );
/* Select The Modelview Matrix */
glMatrixMode( GL_MODELVIEW );
/* Stor the Modelview Matrix */
glPushMatrix( );
/* Reset The Modelview Matrix */
glLoadIdentity( );
/* Position The Text (0,0 - Bottom Left) */
glTranslated( x, y, 0 );
/* Choose The Font Set (0 or 1) */
glListBase( base - 32 + ( 128 * set ) );
/* Write The Text To The Screen */
glCallLists( strlen( string ), GL_BYTE, string );
/* Select The Projection Matrix */
glMatrixMode( GL_PROJECTION );
/* Restore The Old Projection Matrix */
glPopMatrix( );
/* Select the Modelview Matrix */
glMatrixMode( GL_MODELVIEW );
/* Restore the Old Projection Matrix */
glPopMatrix( );
/* Re-enable Depth Testing */
glEnable( GL_DEPTH_TEST );
}
/* Here goes our drawing code */
int drawGLScene( GLvoid )
{
/* These are to calculate our fps */
static GLint T0 = 0;
static GLint Frames = 0;
/* Clear The Screen And The Depth Buffer */
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glLoadIdentity( );
/* Select Our Second Texture */
glBindTexture( GL_TEXTURE_2D, texture[1] );
/* Move Into The Screen 5 Units */
glTranslatef( 0.0f, 0.0f, -5.0f );
/* Rotate On The Z Axis 45 Degrees (Clockwise) */
glRotatef( 45.0f, 0.0f, 0.0f, 1.0f );
/* Rotate On The X & Y Axis By cnt1 (Left To Right) */
glRotatef( cnt1 * 30.0f, 1.0f, 1.0f, 0.0f );
/* Disable Blending Before We Draw In 3D */
glDisable( GL_BLEND );
glColor3f( 1.0f, 1.0f, 1.0f ); /* Bright White */
glBegin( GL_QUADS ); /* Draw Our First Texture Mapped Quad */
glTexCoord2d( 0.0f, 0.0f ); /* First Texture Coord */
glVertex2f( -1.0f, 1.0f ); /* First Vertex */
glTexCoord2d( 1.0f, 0.0f ); /* Second Texture Coord */
glVertex2f( 1.0f, 1.0f ); /* Second Vertex */
glTexCoord2d( 1.0f, 1.0f ); /* Third Texture Coord */
glVertex2f( 1.0f, -1.0f ); /* Third Vertex */
glTexCoord2d( 0.0f, 1.0f ); /* Fourth Texture Coord */
glVertex2f( -1.0f, -1.0f ); /* Fourth Vertex */
glEnd( );
/* Rotate On The X & Y Axis By 90 Degrees (Left To Right) */
glRotatef( 90.0f, 1.0f, 1.0f, 0.0f );
glBegin( GL_QUADS ); /* Draw Our Second Texture Mapped Quad */
glTexCoord2d( 0.0f, 0.0f ); /* First Texture Coord */
glVertex2f( -1.0f, 1.0f ); /* First Vertex */
glTexCoord2d( 1.0f, 0.0f ); /* Second Texture Coord */
glVertex2f( 1.0f, 1.0f ); /* Second Vertex */
glTexCoord2d( 1.0f, 1.0f ); /* Third Texture Coord */
glVertex2f( 1.0f, -1.0f ); /* Third Vertex */
glTexCoord2d( 0.0f, 1.0f ); /* Fourth Texture Coord */
glVertex2f( -1.0f, -1.0f ); /* Fourth Vertex */
glEnd( );
/* Re-enable Blending */
glEnable( GL_BLEND );
/* Reset the view */
glLoadIdentity( );
/* Pulsing Colors Based On Text Position */
/* Print GL Text To The Screen */
glColor3f( 1.0f * ( float )cos( cnt1 ),
1.0f * ( float )sin( cnt2 ),
1.0f - 0.5f * ( float )cos( cnt1 + cnt2 ) );
glPrint( ( int )( 280 + 250 * cos( cnt1 ) ),
( int )( 235 + 200 * sin( cnt2 ) ),
"NeHe", 0 );
glColor3f( 1.0f * ( float )sin( cnt2 ),
1.0f - 0.5f * ( float )cos( cnt1 + cnt2 ),
1.0f * ( float )cos( cnt1 ) );
glPrint( ( int )( 280 + 230 * cos( cnt2 ) ),
( int )( 235 + 200 * sin( cnt1 ) ),
"OpenGL", 1 );
/* Set Color to Red */
glColor3f( 0.0f, 0.0f, 1.0f );
/* Draw Text To The Screen */
glPrint( ( int )( 240 + 200 * cos( ( cnt2 + cnt1 ) / 5 ) ), 2,
"Giuseppe D'Agata", 0 );
/* Set Color To White */
glColor3f( 1.0f, 1.0f, 1.0f );
/* Draw Offset Text To The Screen */
glPrint( ( int )( 242 + 200 * cos( ( cnt2 + cnt1 ) / 5 ) ), 2,
"Giuseppe D'Agata", 0 );
cnt1 += 0.01f; /* Increase The First Counter */
cnt2 += 0.0081f; /* Increase The Second Counter */
/* Draw it to the screen */
SDL_GL_SwapBuffers( );
/* Gather our frames per second */
Frames++;
{
GLint t = SDL_GetTicks();
if (t - T0 >= 5000) {
GLfloat seconds = (t - T0) / 1000.0;
GLfloat fps = Frames / seconds;
printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
T0 = t;
Frames = 0;
}
}
return( TRUE );
}
int main( int argc, char **argv )
{
/* Flags to pass to SDL_SetVideoMode */
int videoFlags;
/* main loop variable */
int done = FALSE;
/* used to collect events */
SDL_Event event;
/* this holds some info about our display */
const SDL_VideoInfo *videoInfo;
/* whether or not the window is active */
int isActive = TRUE;
/* initialize SDL */
if ( SDL_Init( SDL_INIT_VIDEO ) < 0 )
{
fprintf( stderr, "Video initialization failed: %s\n",
SDL_GetError( ) );
Quit( 1 );
}
/* Fetch the video info */
videoInfo = SDL_GetVideoInfo( );
if ( !videoInfo )
{
fprintf( stderr, "Video query failed: %s\n",
SDL_GetError( ) );
Quit( 1 );
}
/* the flags to pass to SDL_SetVideoMode */
videoFlags = SDL_OPENGL; /* Enable OpenGL in SDL */
videoFlags |= SDL_GL_DOUBLEBUFFER; /* Enable double buffering */
videoFlags |= SDL_HWPALETTE; /* Store the palette in hardware */
videoFlags |= SDL_RESIZABLE; /* Enable window resizing */
/* This checks to see if surfaces can be stored in memory */
if ( videoInfo->hw_available )
videoFlags |= SDL_HWSURFACE;
else
videoFlags |= SDL_SWSURFACE;
/* This checks if hardware blits can be done */
if ( videoInfo->blit_hw )
videoFlags |= SDL_HWACCEL;
/* Sets up OpenGL double buffering */
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
/* get a SDL surface */
surface = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,
videoFlags );
/* Verify there is a surface */
if ( !surface )
{
fprintf( stderr, "Video mode set failed: %s\n", SDL_GetError( ) );
Quit( 1 );
}
/* Enable key repeat */
if ( ( SDL_EnableKeyRepeat( 100, SDL_DEFAULT_REPEAT_INTERVAL ) ) )
{
fprintf( stderr, "Setting keyboard repeat failed: %s\n",
SDL_GetError( ) );
Quit( 1 );
}
/* initialize OpenGL */
if ( initGL( ) == FALSE )
{
fprintf( stderr, "Could not initialize OpenGL.\n" );
Quit( 1 );
}
/* Resize the initial window */
resizeWindow( SCREEN_WIDTH, SCREEN_HEIGHT );
/* wait for events */
while ( !done )
{
/* handle the events in the queue */
while ( SDL_PollEvent( &event ) )
{
switch( event.type )
{
case SDL_ACTIVEEVENT:
/* Something's happend with our focus
* If we lost focus or we are iconified, we
* shouldn't draw the screen
*/
if ( event.active.gain == 0 )
isActive = FALSE;
else
isActive = TRUE;
break;
case SDL_VIDEORESIZE:
/* handle resize event */
surface = SDL_SetVideoMode( event.resize.w,
event.resize.h,
16, videoFlags );
if ( !surface )
{
fprintf( stderr, "Could not get a surface after resize: %s\n", SDL_GetError( ) );
Quit( 1 );
}
resizeWindow( event.resize.w, event.resize.h );
break;
case SDL_KEYDOWN:
/* handle key presses */
handleKeyPress( &event.key.keysym );
break;
case SDL_QUIT:
/* handle quit requests */
done = TRUE;
break;
default:
break;
}
}
/* draw the scene */
if ( isActive )
drawGLScene( );
}
/* clean ourselves up and exit */
Quit( 0 );
/* Should never get here */
return( 0 );
}
(I also changed GL_BGR to GL_BGRA_EXT in LoadGLTextures() )
When I attempt to compile this however, I get a bunch of linker errors that seem to be related to OpenGL. Here they are:
Maze error LNK2019: unresolved external symbol __imp__glDeleteLists@8 referenced in function _KillFont
Maze error LNK2019: unresolved external symbol __imp__glDeleteTextures@8 referenced in function _Quit
Maze error LNK2019: unresolved external symbol __imp__glTexParameteri@12 referenced in function _LoadGLTextures
Maze error LNK2019: unresolved external symbol __imp__glTexImage2D@36 referenced in function _LoadGLTextures
Maze error LNK2019: unresolved external symbol __imp__glBindTexture@8 referenced in function _LoadGLTextures
Maze error LNK2019: unresolved external symbol __imp__glGenTextures@8 referenced in function _LoadGLTextures
Maze error LNK2019: unresolved external symbol __imp__glEndList@0 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glTranslated@24 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glEnd@0 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glVertex2i@8 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glTexCoord2f@8 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glBegin@4 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glNewList@8 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol __imp__glGenLists@4 referenced in function _BuildFont
Maze error LNK2019: unresolved external symbol _gluPerspective@32 referenced in function _resizeWindow
Maze error LNK2019: unresolved external symbol __imp__glLoadIdentity@0 referenced in function _resizeWindow
Maze error LNK2019: unresolved external symbol __imp__glMatrixMode@4 referenced in function _resizeWindow
Maze error LNK2019: unresolved external symbol __imp__glViewport@16 referenced in function _resizeWindow
Maze error LNK2019: unresolved external symbol __imp__glEnable@4 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glBlendFunc@8 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glDepthFunc@4 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glClearDepth@8 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glClearColor@16 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glShadeModel@4 referenced in function _initGL
Maze error LNK2019: unresolved external symbol __imp__glPopMatrix@0 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glCallLists@12 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glListBase@4 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glOrtho@48 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glPushMatrix@0 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glDisable@4 referenced in function _glPrint
Maze error LNK2019: unresolved external symbol __imp__glVertex2f@8 referenced in function _drawGLScene
Maze error LNK2019: unresolved external symbol __imp__glTexCoord2d@16 referenced in function _drawGLScene
Maze error LNK2019: unresolved external symbol __imp__glColor3f@12 referenced in function _drawGLScene
Maze error LNK2019: unresolved external symbol __imp__glRotatef@16 referenced in function _drawGLScene
Maze error LNK2019: unresolved external symbol __imp__glTranslatef@12 referenced in function _drawGLScene
Maze error LNK2019: unresolved external symbol __imp__glClear@4 referenced in function _drawGLScene
Maze fatal error LNK1120: 36 unresolved externals
Can anyone tell me what I'm doing wrong here? I can compile OpenGL programs just fine, and SDL programs just fine, but when I mix the two, it blows up with linker errors. I am compiling this using VS.NET 2003 C++
[edited by - toddhd on June 7, 2004 3:44:10 PM]
[edited by - toddhd on June 7, 2004 3:45:38 PM]
-Todd"Windows dectected that your mouse has moved. Please reboot for the changes to take effect"
