VertexArray append creating extra vertices

[NGM88]

I ran into something weird while merging 2 vertex arrays:

I have an empty vertex array called "vaInterface", and a vertexarray called just "va" in a class called "PanelBottom" with a size of 4. Both are quads. I append "va" and the size of "vaInterface" becomes 8! code:

std::cout << vaInterface.getVertexCount() << std::endl; // PRINTS 0
std::cout << objPanelBottom.va.getVertexCount() << std::endl; // PRINTS 4
std::cout << vaInterface.getVertexCount() + objPanelBottom.va.getVertexCount() << std::endl; // PRINTS 4

vaInterface.resize(vaInterface.getVertexCount() + objPanelBottom.va.getVertexCount());
for (unsigned int i = 0; i < objPanelBottom.va.getVertexCount(); i++)
{
    vaInterface.append(objPanelBottom.va[i]);
}

std::cout << vaInterface.getVertexCount() << std::endl; // PRINTS 8
 

If I then print the positions of each vertex, the first 4 are all 0s. 5 through 8 are positioned correctly.

Anyone know why this is?

edit: VertexCount keeps doubling when I append other vertexarrays to vaInterface. I added another vertexarray with size 4 and now the total size is 16 when it should be 8.

[achpile]

i guess append resizes your vaInterface. so you have 8 = resize(4) + 4 * append(1).

[NGM88]

i guess append resizes your vaInterface. so you have 8 = resize(4) + 4 * append(1).

Thanks, that makes sense. Definitely doesn't say that in the documentation though.

[eXpl0it3r]

Neither does it say you need to resize your vertex array first before inserting.

Append is a very common function name and that it automatically adjusts the target container is an assumption you'll find for pretty much any container that implements an append function in pretty much any programming language.