Polling Events in SDL
Post: #1
Hi,
I have been learning SDL and am now trying implement it by making a pong clone. I have drawn the two players and the ball and am now trying to use input to make the players move.
This is what my main loop looks like
The playerAInput function lools like this
and my updateScreen
When I run my code it seems to get stuck and can't close normal or update the screen. I think it is the way that I am using the polling event. What am I doing wrong?
I have been learning SDL and am now trying implement it by making a pong clone. I have drawn the two players and the ball and am now trying to use input to make the players move.
This is what my main loop looks like
Code:
// Main Loop
for(;;)
{
playerAInput();
updateScreen();
}The playerAInput function lools like this
Code:
SDL_Event inputEvent;
void playerAInput()
{
while (SDL_PollEvent(&inputEvent))
{
switch (inputEvent.type)
{
case SDL_KEYDOWN:
switch(inputEvent.key.keysym.sym)
{
case SDLK_UP:
playerAY -= 5;
break;
case SDLK_DOWN:
playerAY += 5;
break;
case SDLK_q:
SDL_QUIT;
break;
default:
break;
}
}
}
}and my updateScreen
Code:
void updateScreen()
{
SDL_UpdateRect(displaySurface,0,0,0,0);
}When I run my code it seems to get stuck and can't close normal or update the screen. I think it is the way that I am using the polling event. What am I doing wrong?
Post: #2
The reason you can't close the screen normally is because you didn't handle SDL_QUIT properly. SDL_QUIT is a type of event you get from SDL_PollEvent(), not a macro or anything. In your key handler, instead of using "SDL_QUIT;" you'd call SDL_Quit() along with an exit(0), because SQL_Quit() doesn't actually quit your app (it just shuts down SDL's subsystems). Just do the same thing in your SDL_QUIT handler.
I don't know why your SDL_UpdateRect() call isn't working. Try passing in SDL_GetVideoSurface() instead of your displaySurface variable and see if that works.
I don't know why your SDL_UpdateRect() call isn't working. Try passing in SDL_GetVideoSurface() instead of your displaySurface variable and see if that works.
Since when was "Fred" a placeholder variable?
Post: #3
I suggest you start from a tutorial/working code, getting something working from the documentation alone is often close to impossible.
©h€ck øut µy stuƒƒ åt ragdollsoft.com
New game in development Rubber Ninjas - Mac Games Downloads
Post: #4
OK so I got the input funtion to work correct, but am still having problems with getting the screen to update. I found a tutorial and coppied it right out of the article and pasted it into xcode.
I even got the same image they were using. When i build and go I get the error that it can't load the BMP file and app closes. I have the BMP file in my resources folder now but tried it everywhere i can imagine it being in the project. Do i have to put it somewhere special for SDL to pick it up?
Code:
SDL_Surface *image;
SDL_Surface *temp;
temp = SDL_LoadBMP("image.bmp");
if (temp == NULL)
{
printf("Unable to load bitmap: %s\n", SDL_GetError());
exit(0);
}
image = SDL_DisplayFormat(temp);
SDL_FreeSurface(temp);
SDL_Rect src, dest;
src.x = 0;
src.y = 0;
src.w = image->w;
src.h = image->h;
dest.x = 100;
dest.y = 100;
dest.w = image->w;
dest.h = image->h;
SDL_BlitSurface(image, &src, displaySurface, &dest);
SDL_Flip(displaySurface);I even got the same image they were using. When i build and go I get the error that it can't load the BMP file and app closes. I have the BMP file in my resources folder now but tried it everywhere i can imagine it being in the project. Do i have to put it somewhere special for SDL to pick it up?
Post: #6
Awsome! I added the files in where the app is located in the debug folder. Is there a way that I can have it pick up the resources that are inside the app? When I "Show Package Contents" and open the resources i see all my resources that are in xcode.
Post: #7
try replacing the function "setupWorkingDirectory" in SDLMain.m with OSC's CF code i.e.
Code:
CFBundleRef mainBundle = CFBundleGetMainBundle();
CFURLRef resourcesURL = CFBundleCopyResourcesDirectoryURL(mainBundle);
char path[PATH_MAX];
if (!CFURLGetFileSystemRepresentation(resourcesURL, TRUE, (UInt8 *)path, PATH_MAX))
{
// error!
}
CFRelease(resourcesURL);
chdir(path);©h€ck øut µy stuƒƒ åt ragdollsoft.com
New game in development Rubber Ninjas - Mac Games Downloads
Post: #9
So that your code is 7 lines longer when bragging about your project's size, obviously 
©h€ck øut µy stuƒƒ åt ragdollsoft.com
New game in development Rubber Ninjas - Mac Games Downloads
