C++ - Heap Corruption on UInt32*

Question

I am currently programming a game on C++ and am working with the SDL 2.0 library.

I am attempting to disect a 32x32 image from a texture to store as a tile and am attempting to recreate it from the pixels of a texture. When I run this code and attempt to edit the Uint32* by a for loop, I can edit it but once I try to creat the image, I get a heap corruption.

I currently have this code running:

Uint32* pixels = (Uint32*)m_pSprite->GetPixels();
int pixelCount = (m_pSprite->GetPitch() / 4) * m_pSprite->GetHeight();

int tileOffset = 0;
int spriteSheetOffset = 0;
int widthOffset = m_pSprite->GetWidth();

Uint32* tilePixels = new Uint32(32);
for (int y = 0; y < 32; y++)
{
    tileOffset = (y * 32);
    spriteSheetOffset = (y * widthOffset);
    for (int x = 0; x < 32; x++)
    {   
        tilePixels[tileOffset + x] = pixels[spriteSheetOffset + x];
    }
}

int tilePitch = 32*4;
SDL_Texture* texture = SDL_CreateTexture(backBuffer.GetRenderer(), SDL_PIXELFORMAT_RGB888, SDL_TEXTUREACCESS_TARGET, TILE_WIDTH, TILE_HEIGHT);

I can see that there is something wrong with the Uint32* variable and that this is obviously not a best practice but I am still wrapping my head around what can and cannot be done, and what is the best way etc.

Does anyone have an explanation of what could be happening?

Answer 1

Uint32* tilePixels = new Uint32(32);

This is dynamically allocating a single Uint32, and initializing/constructing it to the value 32. It seems you want a 32*32 array of those. Try this:

Uint32* tilePixels = new Uint32[32*32]; // brackets allocate an array

Although, since the size of your array is static (known at compile-time), it would be best to just use a stack-allocated array instead of a dynamic one:

Uint32 tilePixels[32*32];

See if that fixes it.