I've written a model loader in C++ an OpenGL. I've used std::vector
s to store my vertex data, but now I want to pass it to glBufferData()
, however the data types are wildly different. I want to know if there's a way to convert between std::vector
to the documented const GLvoid *
for glBufferData()
.
typedef struct
{
float x, y, z;
float nx, ny, nz;
float u, v;
}
Vertex;
vector<Vertex> vertices;
glBufferData(GL_ARRAY_BUFFER, vertices.size() * 3 * sizeof(float), vertices, GL_STATIC_DRAW);
I get the following (expected) error:
error: cannot convert ‘std::vector<Vertex>’ to ‘const GLvoid*’ in argument passing
How can I convert the vector to a type compatible with glBufferData()
?
NB. I don't care about correct memory allocation at the moment; vertices.size() * 3 * sizeof(float)
will most likely segfault, but I want to solve the type error first.
If you have a std::vector<T> v
, you may obtain a T*
pointing to the start of the contiguous data (which is what OpenGL is after) with the expression &v[0]
.
In your case, this means passing a Vertex*
to glBufferData
:
glBufferData(
GL_ARRAY_BUFFER,
vertices.size() * sizeof(Vertex),
&vertices[0],
GL_STATIC_DRAW
);
Or like this, which is the same:
glBufferData(
GL_ARRAY_BUFFER,
vertices.size() * sizeof(Vertex),
&vertices.front(),
GL_STATIC_DRAW
);
You can rely on implicit conversion from Vertex*
to void const*
here; that should not pose a problem.