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I am doing this lazyfoo SDL tutorial right now.
The render class they using has some image to texture function which is using SDL_Surface* and SDL_Texture.
At the end of the function they "free" the created surface by calling SDL_FreeSurface().
Now, I am wondering:
- Why exactly i have to free the Surface at all (variables are local?)?
- Why its ok to let the created Texture be without calling
SDL_DestroyTexture? - What exacty does it mean when i destroy a texture or free a surface?
bool Tile::loadTexture(const char* path)
SDL_Texture* newTexture = NULL;
SDL_Surface* loadedSurface = IMG_Load(path);
//...some code
Texture = newTexture;
SDL_FreeSurface(loadedSurface);
return Texture != NULL;
c++ sdl
edited Mar 24 at 22:17
Quentin
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
add a comment |
I am doing this lazyfoo SDL tutorial right now.
The render class they using has some image to texture function which is using SDL_Surface* and SDL_Texture.
At the end of the function they "free" the created surface by calling SDL_FreeSurface().
Now, I am wondering:
- Why exactly i have to free the Surface at all (variables are local?)?
- Why its ok to let the created Texture be without calling
SDL_DestroyTexture? - What exacty does it mean when i destroy a texture or free a surface?
bool Tile::loadTexture(const char* path)
SDL_Texture* newTexture = NULL;
SDL_Surface* loadedSurface = IMG_Load(path);
//...some code
Texture = newTexture;
SDL_FreeSurface(loadedSurface);
return Texture != NULL;
c++ sdl
edited Mar 24 at 22:17
Quentin
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
Are you familiar withfopen/fclose? The situation with those functions is similar.
– HolyBlackCat
Mar 24 at 21:21
add a comment |
I am doing this lazyfoo SDL tutorial right now.
The render class they using has some image to texture function which is using SDL_Surface* and SDL_Texture.
At the end of the function they "free" the created surface by calling SDL_FreeSurface().
Now, I am wondering:
- Why exactly i have to free the Surface at all (variables are local?)?
- Why its ok to let the created Texture be without calling
SDL_DestroyTexture? - What exacty does it mean when i destroy a texture or free a surface?
bool Tile::loadTexture(const char* path)
SDL_Texture* newTexture = NULL;
SDL_Surface* loadedSurface = IMG_Load(path);
//...some code
Texture = newTexture;
SDL_FreeSurface(loadedSurface);
return Texture != NULL;
c++ sdl
edited Mar 24 at 22:17
Quentin
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
I am doing this lazyfoo SDL tutorial right now.
The render class they using has some image to texture function which is using SDL_Surface* and SDL_Texture.
At the end of the function they "free" the created surface by calling SDL_FreeSurface().
Now, I am wondering:
- Why exactly i have to free the Surface at all (variables are local?)?
- Why its ok to let the created Texture be without calling
SDL_DestroyTexture? - What exacty does it mean when i destroy a texture or free a surface?
bool Tile::loadTexture(const char* path)
SDL_Texture* newTexture = NULL;
SDL_Surface* loadedSurface = IMG_Load(path);
//...some code
Texture = newTexture;
SDL_FreeSurface(loadedSurface);
return Texture != NULL;
c++ sdl
c++ sdl
edited Mar 24 at 22:17
Quentin
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
edited Mar 24 at 22:17
Quentin
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
edited Mar 24 at 22:17
Quentin
47.8k694152
edited Mar 24 at 22:17
Quentin
47.8k694152
edited Mar 24 at 22:17
Quentin
47.8k694152
47.8k694152
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
asked Mar 24 at 21:18
KingKoopaKingKoopa
42
42
Are you familiar withfopen/fclose? The situation with those functions is similar.
– HolyBlackCat
Mar 24 at 21:21
add a comment |
Are you familiar withfopen/fclose? The situation with those functions is similar.
– HolyBlackCat
Mar 24 at 21:21
Are you familiar with
fopen/fclose? The situation with those functions is similar.– HolyBlackCat
Mar 24 at 21:21
Are you familiar with
fopen/fclose? The situation with those functions is similar.– HolyBlackCat
Mar 24 at 21:21
add a comment |
1 Answer
1
active
oldest
votes
Why exactly i have to free the Surface at all (variables are local?)?
The pointer loadedSurface is local. The actual surface isn't: there is something similar to malloc inside of IMG_Load. The same way you use free on memory allocated with malloc, you use SDL_FreeSurface on surfaces allocated with IMG_Load (or SDL_CreateRGBSurface and so on).
Why its ok to let the created Texture be without calling SDL_DestroyTexture?
SDL_DestroyTexture is called, inside of LTexture::free, which is called by the destructor of LTexture. So SDL_DestroyTexture is pretty much guaranteed to be called at some point if loadFromFile was called.
What exacty does it mean when i destroy a texture or free a surface?
It means the same thing as using free on memory allocated with malloc, or using delete on memory allocated with new, or calling std::unique_ptr::reset (without argument), and so on. Each variant does something sligthly different. If you want to know what exactly differs between SDL_DestroyTexture, SDL_FreeSurface, free, etc, you can look at the source code: SDL is open source and there are quite a few open source implementations of free out there.
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction inloadFromFile,mTexture = newTexture;, makesmTexturehold the texture beforenewTexturegoes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly usingmTexture. It's functionally the same, but would be less confusing.
– Nelfeal
Mar 27 at 14:53
add a comment |
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Why exactly i have to free the Surface at all (variables are local?)?
The pointer loadedSurface is local. The actual surface isn't: there is something similar to malloc inside of IMG_Load. The same way you use free on memory allocated with malloc, you use SDL_FreeSurface on surfaces allocated with IMG_Load (or SDL_CreateRGBSurface and so on).
Why its ok to let the created Texture be without calling SDL_DestroyTexture?
SDL_DestroyTexture is called, inside of LTexture::free, which is called by the destructor of LTexture. So SDL_DestroyTexture is pretty much guaranteed to be called at some point if loadFromFile was called.
What exacty does it mean when i destroy a texture or free a surface?
It means the same thing as using free on memory allocated with malloc, or using delete on memory allocated with new, or calling std::unique_ptr::reset (without argument), and so on. Each variant does something sligthly different. If you want to know what exactly differs between SDL_DestroyTexture, SDL_FreeSurface, free, etc, you can look at the source code: SDL is open source and there are quite a few open source implementations of free out there.
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction inloadFromFile,mTexture = newTexture;, makesmTexturehold the texture beforenewTexturegoes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly usingmTexture. It's functionally the same, but would be less confusing.
– Nelfeal
Mar 27 at 14:53
add a comment |
Why exactly i have to free the Surface at all (variables are local?)?
The pointer loadedSurface is local. The actual surface isn't: there is something similar to malloc inside of IMG_Load. The same way you use free on memory allocated with malloc, you use SDL_FreeSurface on surfaces allocated with IMG_Load (or SDL_CreateRGBSurface and so on).
Why its ok to let the created Texture be without calling SDL_DestroyTexture?
SDL_DestroyTexture is called, inside of LTexture::free, which is called by the destructor of LTexture. So SDL_DestroyTexture is pretty much guaranteed to be called at some point if loadFromFile was called.
What exacty does it mean when i destroy a texture or free a surface?
It means the same thing as using free on memory allocated with malloc, or using delete on memory allocated with new, or calling std::unique_ptr::reset (without argument), and so on. Each variant does something sligthly different. If you want to know what exactly differs between SDL_DestroyTexture, SDL_FreeSurface, free, etc, you can look at the source code: SDL is open source and there are quite a few open source implementations of free out there.
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction inloadFromFile,mTexture = newTexture;, makesmTexturehold the texture beforenewTexturegoes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly usingmTexture. It's functionally the same, but would be less confusing.
– Nelfeal
Mar 27 at 14:53
add a comment |
Why exactly i have to free the Surface at all (variables are local?)?
The pointer loadedSurface is local. The actual surface isn't: there is something similar to malloc inside of IMG_Load. The same way you use free on memory allocated with malloc, you use SDL_FreeSurface on surfaces allocated with IMG_Load (or SDL_CreateRGBSurface and so on).
Why its ok to let the created Texture be without calling SDL_DestroyTexture?
SDL_DestroyTexture is called, inside of LTexture::free, which is called by the destructor of LTexture. So SDL_DestroyTexture is pretty much guaranteed to be called at some point if loadFromFile was called.
What exacty does it mean when i destroy a texture or free a surface?
It means the same thing as using free on memory allocated with malloc, or using delete on memory allocated with new, or calling std::unique_ptr::reset (without argument), and so on. Each variant does something sligthly different. If you want to know what exactly differs between SDL_DestroyTexture, SDL_FreeSurface, free, etc, you can look at the source code: SDL is open source and there are quite a few open source implementations of free out there.
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
Why exactly i have to free the Surface at all (variables are local?)?
The pointer loadedSurface is local. The actual surface isn't: there is something similar to malloc inside of IMG_Load. The same way you use free on memory allocated with malloc, you use SDL_FreeSurface on surfaces allocated with IMG_Load (or SDL_CreateRGBSurface and so on).
Why its ok to let the created Texture be without calling SDL_DestroyTexture?
SDL_DestroyTexture is called, inside of LTexture::free, which is called by the destructor of LTexture. So SDL_DestroyTexture is pretty much guaranteed to be called at some point if loadFromFile was called.
What exacty does it mean when i destroy a texture or free a surface?
It means the same thing as using free on memory allocated with malloc, or using delete on memory allocated with new, or calling std::unique_ptr::reset (without argument), and so on. Each variant does something sligthly different. If you want to know what exactly differs between SDL_DestroyTexture, SDL_FreeSurface, free, etc, you can look at the source code: SDL is open source and there are quite a few open source implementations of free out there.
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
answered Mar 26 at 17:41
NelfealNelfeal
5,2921826
5,2921826
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction inloadFromFile,mTexture = newTexture;, makesmTexturehold the texture beforenewTexturegoes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly usingmTexture. It's functionally the same, but would be less confusing.
– Nelfeal
Mar 27 at 14:53
add a comment |
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction inloadFromFile,mTexture = newTexture;, makesmTexturehold the texture beforenewTexturegoes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly usingmTexture. It's functionally the same, but would be less confusing.
– Nelfeal
Mar 27 at 14:53
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
the free funktion uses SDL_DestroyTexture for the one texture "mTexture" declared inside of the class but not for the texture declared inside of the loadFromFile function "newTexture". i will take a other look on the memory allocation stuff. thank yo so far
– KingKoopa
Mar 26 at 18:37
The second last instruction in
loadFromFile, mTexture = newTexture;, makes mTexture hold the texture before newTexture goes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly using mTexture. It's functionally the same, but would be less confusing.– Nelfeal
Mar 27 at 14:53
The second last instruction in
loadFromFile, mTexture = newTexture;, makes mTexture hold the texture before newTexture goes out of scope. It's still the same texture though, only its address is being copied. I actually don't know why the author uses a local variable here instead of directly using mTexture. It's functionally the same, but would be less confusing.– Nelfeal
Mar 27 at 14:53
add a comment |
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Are you familiar with
fopen/fclose? The situation with those functions is similar.– HolyBlackCat
Mar 24 at 21:21