Lock a portion of the texture for write-only pixel access.
int SDL_LockTexture(SDL_Texture * texture,
const SDL_Rect * rect,
void **pixels, int *pitch);
|the texture to lock for access, which was created with
|an SDL_Rect structure representing the area to lock for access; NULL to lock the entire texture
|this is filled in with a pointer to the locked pixels, appropriately offset by the locked area
|this is filled in with the pitch of the locked pixels; the pitch is the length of one row in bytes
Returns 0 on success or a negative error code if the texture is not valid or was not created with
SDL_TEXTUREACCESS_STREAMING; call SDL_GetError() for more information.
As an optimization, the pixels made available for editing don't necessarily contain the old texture data. This is a write-only operation, and if you need to keep a copy of the texture data you should do that at the application level.
You must use SDL_UnlockTexture() to unlock the pixels and apply any changes.
This function is available since SDL 2.0.0.