I'm learning C++ and graphics programming, and following a tutorial, but I can't seem to be able to find any solutions to this problem.
This is the code:
struct CUSTOMVERTEX { FLOAT X, Y, Z; DWORD COLOR; };
void writetovram(struct CUSTOMVERTEX *verticies)
{
...
memcpy(pVoid, verticies, sizeof(verticies));
...
return;
}
void createshapes()
{
//simple square
CUSTOMVERTEX verticies[] =
{
{ -3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ 3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ 3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
};
writetovram(&verticies);
}
I need to be able to pass this struct array in its entirety as a pointer to the function. I've found that if I havn't used pointers then the data doesn't get transferred properly.
I've tried:
void writetovram(struct CUSTOMVERTEX *verticies)
void writetovram(struct CUSTOMVERTEX verticies)
void writetovram(struct CUSTOMVERTEX &verticies)
void writetovram(struct CUSTOMVERTEX *verticies[])
void writetovram(struct CUSTOMVERTEX verticies[])
and
writetovram(&verticies);
writetovram(*verticies);
writetovram(verticies);
Edit: When I put the code like this, it works:
void writetovram()
{
CUSTOMVERTEX verticies[] =
{
{ -3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ 3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ 3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
};
...
memcpy(pVoid, verticies, sizeof(verticies));
...
return;
}
Basically, all the combinations of pointers and syntax I could think of. But none have worked.
Can anyone help?
I've also searched online and found none having this problem.
Inside of writetovram(), sizeof(verticies) doesn't return what you think it does. You can't get the size of an array from just a pointer. There are TONS of questions on StackOverflow on this issue.
Your simplest option is to just pass the array size as another parameter, eg:
struct CUSTOMVERTEX { FLOAT X, Y, Z; DWORD COLOR; };
void writetovram(CUSTOMVERTEX *verticies, int num_verticies)
{
...
memcpy(pVoid, verticies, sizeof(*verticies) * num_verticies);
...
}
void createshapes()
{
//simple square
CUSTOMVERTEX verticies[] =
{
{ -3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ 3.0f, 3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ 3.0f, -3.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 255), },
};
writetovram(verticies, 4);
// or:
// writetovram(verticies, sizeof(verticies)/sizeof(verticies[0]));
// or:
// writetovram(verticies, std::size(verticies));
}
Other options include:
pass the array by reference, but only if the size is known at compile-time. But if multiple different-sized arrays need to be used, then writetovram() would have to be made into a template function so the array size can be deduced at compile-time for each call site.
changing the array to use std::array or std:vector instead, passed to the function by reference, and then it can use their size() methods.
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments