Quad

void Quad::init()
{
glm::vec3 left = glm::cross(n, u);
glm::vec3 uppercenter = (u * height/2.0f) + p;
glm::vec3 tl = uppercenter + (left * width/2.0f);
glm::vec3 tr = uppercenter – (left * width/2.0f);
glm::vec3 bl = tl – (u * height);
glm::vec3 br = tr – (u * height);

// face 1
vbo.addData(&bl[0], sizeof(glm::vec3)); // vertex position
vbo.addData(&color[0], sizeof(glm::vec3)); // vertex color
vbo.addData(&br[0], sizeof(glm::vec3));
vbo.addData(&color[0], sizeof(glm::vec3));
vbo.addData(&tr[0], sizeof(glm::vec3));
vbo.addData(&color[0], sizeof(glm::vec3));

// face 2
vbo.addData(&bl[0], sizeof(glm::vec3));
vbo.addData(&color[0], sizeof(glm::vec3));
vbo.addData(&tr[0], sizeof(glm::vec3));
vbo.addData(&color[0], sizeof(glm::vec3));
vbo.addData(&tl[0], sizeof(glm::vec3));
vbo.addData(&color[0], sizeof(glm::vec3));

numVertices = 6;

// VAO & VBOs
vbo.createVBO();
vbo.bindVBO();
vbo.uploadDataToGPU(GL_STATIC_DRAW);

glGenVertexArrays(1, &vao);
glBindVertexArray(vao);

int iDataStride = 2 * sizeof(glm::vec3); // vertex & color only
int iDataOffset = 0;
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, iDataStride, (void*)iDataOffset);
iDataOffset += sizeof(glm::vec3);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, iDataStride, (void*)iDataOffset);

isLoaded = true;
}