Tiny Core Linux
General TC => General TC Talk => Topic started by: jackarius86 on May 18, 2013, 03:20:39 AM
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Have been getting back into some opengl programming lately and first went down the route of setting up with glut and had no problems what so ever.
Ideally I would like to work with SDL but am having problems whenevr i call SDL_SetVideoMode() as it makes the entire screen go dim for some reason, i have to then exit to prompt and startx.
I have trawled the internet for this problem, have TRIED to ask in the SDL forum but I dont think i have permission to post there or something like that..
Can anyone please help me?
Thanks.
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Hi jackarius86
What values are you passing to SDL_SetVideoMode()? Are using 0 for bpp or trying to force it to some other value?
Is it returning a valid value or NULL? Did you try single stepping with gdb to make sure the SDL_SetVideoMode()
instruction is causing it and not some later instruction?
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Hi rich,
Im not at the computer now but off the top of my head
SDL_SetVideoMode(400, 400, 0 | SDL_Opengl)
other values such as 8, 24, 32 have been tried to the same effect.
i didnt use gdb i used getchar() between function calls so i could tell it was this particular call.
The program compiles and runs as expected with the added side effect of a dim screen on all workspaces which wont go away not even when i end the program.
to get the screen back to full brightness i have to exit to prompt and then startx which is not ideal.
It also maybe worth me mentioning that this work is being done on a laptop.
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Hi jackarius86
Im not at the computer now but off the top of my head
SDL_SetVideoMode(400, 400, 0 | SDL_Opengl)
Well that's obviously not right, SDL_SetVideoMode takes four parameters. Maybe you meant:
SDL_SetVideoMode(400, 400, 0, SDL_Opengl)You might want to take a closer look at the events leading up to that instruction. This page:
http://www.libsdl.org/docs/html/sdlsetvideomode.html
states:
SDL_OPENGL Create an OpenGL rendering context. You should have previously set OpenGL video attributes with SDL_GL_SetAttribute.
If you haven't already read it, this might be worth taking a look at:
http://www.libsdl.org/docs/html/guidevideoopengl.html
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this is the code i am using, mostly cut from an example:
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
#include <iostream>
using namespace std;
//Screen attributes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 0;
//The frame rate
const int FRAMES_PER_SECOND = 1;
//Event handler
SDL_Event event;
//Rendering flag
bool renderQuad = true;
//The timer
class Timer
{
private:
//The clock time when the timer started
int startTicks;
//The ticks stored when the timer was paused
int pausedTicks;
//The timer status
bool paused;
bool started;
public:
//Initializes variables
Timer();
//The various clock actions
void start();
void stop();
void pause();
void unpause();
//Gets the timer's time
int get_ticks();
//Checks the status of the timer
bool is_started();
bool is_paused();
};
bool initGL()
{
//Initialize Projection Matrix
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
//Initialize Modelview Matrix
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
//Initialize clear color
glClearColor( 0.f, 0.f, 0.f, 1.f );
//Check for error
GLenum error = glGetError();
if( error != GL_NO_ERROR )
{
printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) );
return false;
}
return true;
}
bool init()
{
//Initialize SDL
if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
{
return false;
}
//Fault finding
cout<<"1";
getchar();
cout<<"\n";
SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
//Fault finding
cout<<"2";
getchar();
cout<<"\n";
//Create Window
if( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL ) == NULL )
{
return false;
}
//Fault finding
cout<<"3";
getchar();
cout<<"\n";
//Enable unicode
SDL_EnableUNICODE( SDL_TRUE );
//Fault finding
cout<<"4";
getchar();
cout<<"\n";
//Initialize OpenGL
if( initGL() == false )
{
return false;
}
//Fault finding
cout<<"5";
getchar();
cout<<"\n";
//Set caption
SDL_WM_SetCaption( "OpenGL Test", NULL );
return true;
}
void handleKeys( unsigned char key, int x, int y )
{
//Toggle quad
if( key == 'q' )
{
renderQuad = !renderQuad;
}
}
void update()
{
}
void render()
{
//Clear color buffer
glClear( GL_COLOR_BUFFER_BIT );
//Render quad
if( renderQuad == true )
{
glBegin( GL_QUADS );
glVertex2f( -0.5f, -0.5f );
glVertex2f( 0.5f, -0.5f );
glVertex2f( 0.5f, 0.5f );
glVertex2f( -0.5f, 0.5f );
glEnd();
}
//Update screen
SDL_GL_SwapBuffers();
}
void clean_up()
{
//Quit SDL
SDL_Quit();
}
Timer::Timer()
{
//Initialize the variables
startTicks = 0;
pausedTicks = 0;
paused = false;
started = false;
}
void Timer::start()
{
//Start the timer
started = true;
//Unpause the timer
paused = false;
//Get the current clock time
startTicks = SDL_GetTicks();
}
void Timer::stop()
{
//Stop the timer
started = false;
//Unpause the timer
paused = false;
}
void Timer::pause()
{
//If the timer is running and isn't already paused
if( ( started == true ) && ( paused == false ) )
{
//Pause the timer
paused = true;
//Calculate the paused ticks
pausedTicks = SDL_GetTicks() - startTicks;
}
}
void Timer::unpause()
{
//If the timer is paused
if( paused == true )
{
//Unpause the timer
paused = false;
//Reset the starting ticks
startTicks = SDL_GetTicks() - pausedTicks;
//Reset the paused ticks
pausedTicks = 0;
}
}
int Timer::get_ticks()
{
//If the timer is running
if( started == true )
{
//If the timer is paused
if( paused == true )
{
//Return the number of ticks when the timer was paused
return pausedTicks;
}
else
{
//Return the current time minus the start time
return SDL_GetTicks() - startTicks;
}
}
//If the timer isn't running
return 0;
}
bool Timer::is_started()
{
return started;
}
bool Timer::is_paused()
{
return paused;
}
int main( int argc, char *argv[] )
{
//Quit flag
bool quit = false;
//Initialize
if( init() == false )
{
return 1;
}
//The frame rate regulator
Timer fps;
//Wait for user exit
while( quit == false )
{
//Start the frame timer
fps.start();
//While there are events to handle
while( SDL_PollEvent( &event ) )
{
if( event.type == SDL_QUIT )
{
quit = true;
}
else if( event.type == SDL_KEYDOWN )
{
//Handle keypress with current mouse position
int x = 0, y = 0;
SDL_GetMouseState( &x, &y );
handleKeys( event.key.keysym.unicode, x, y );
}
}
//Run frame update
update();
//Render frame
render();
//Cap the frame rate
if( fps.get_ticks() < 1000 / FRAMES_PER_SECOND )
{
SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps.get_ticks() );
}
}
//Clean up
clean_up();
return 0;
}
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Hi jackarius86
Does it work any better using:
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32);
SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 8);
if((Surf_Display = SDL_SetVideoMode(640, 480, 32, SDL_OPENGL)) == NULL)
return false;
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Hi Rich,
I tried that but got the same results :(
I also posted in libsdl.org about this problem but still havent had any replies :( - http://forums.libsdl.org/viewtopic.php?t=9085
Looks like i will have to stick to glut for the meantime :(
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Hi jackarius86
Some laptops dim the screen when they think they are running off of the batteries. If you disconnect and reconnect
the supply, is the brightness restored?
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Hi rich i have heard similar theories to explain this behaviour.. unfortunately i havent got a battery for my laptop so i couldnt possibly test it!
I think im at a dead end with it and will use sfml instead as it seems to work fine!
thanks for your input though :-)
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Just for reference:
I have just discovered that after using the Ctrl-Alt F1 shortcut which takes you back to the original prompt (or alternatively Ctrl-Alt F3) ; and then returning back to the window manager screen, the screen turns dim and seems to be identical to the earlier reported fault.
Does anyone have a good idea about what might be causing this? Thankyou :)
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Buggy video driver then. What X server are you using?
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I'm using Xorg-7.6