OpenGL Core profile - Array of arrays in glBufferData for VBOs

Question

I want to send each face as VBO, and I structured the data as this

facevbo[0] =  x x x x x x   //x,y,z,r,g,b,s,t
facevbo[1] =  x x x x x
facevbo[2] =  x x x x x x x 
facevbo[3] =  x x x x
.
.
.
facevbo[numfaces] = x x x x 

Basicly I have dynamic 2d array with different column size:

GLfloat** faceVBO = new GLfloat*[m_numOfFaces];
faceVBO[dfaceIndex] = new GLfloat[pFace->numOfVerts*8];

When I print all the faces, everything is fine, but when im trying to put them to use, i have problem at this line: (ideally I would iterate trough all the faces to bind each face, but lets take the first column)

glBufferData(GL_ARRAY_BUFFER, 4*oindices, faceVBO[0], GL_STATIC_DRAW);

the third parameter (faceVBO[0]) "argument of type GLfloat is incompatible with param. of type const void*"

but if i tead from array, like

GLfloat facevbo[] = {x,x,x,x...}

and

 glBufferData(GL_ARRAY_BUFFER, 4*oindices, faceVBO, GL_STATIC_DRAW);

it works OK. How should i send the data in this case?

Thanks

Answer 1

The problem is you are passing an address value to data rather than the data itself. A naive solution is to change:

glBufferData(GL_ARRAY_BUFFER, 4*oindices, faceVBO[0], GL_STATIC_DRAW);

to:

glBufferData(GL_ARRAY_BUFFER, 4*oindices, *faceVBO[0], GL_STATIC_DRAW);

To clarify: in your implementation, 'faceVBO' is a pointer to a set of pointers, and glBufferData() requires a pointer to the data, so sending it 'faceVBO[0]' directly is an attempt to send the pointer to the data as the data itself, which is incorrect.