Using C++ std::Vector in glVertexPointer OpenGL function - c++

Question

I have a vector of floats, this vector describes a set of triangles each triangle is described using 18 floats, first 3 are the first vertex, next 3 decribes the normal of the last vertex, and so on 3 times until describe each triangle.
i am using
std::vector< GLfloat >
to store all numbers, and this is my code to render the triangles
void Visualizer::draw3dModel()
{
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glNormalPointer(GL_FLOAT, 6 * sizeof(GLfloat), this->vertexes->data() + 3);
glVertexPointer(3, GL_FLOAT, 6 * sizeof(GLfloat), this->vertexes->data());
glPushMatrix();
glScalef(0.05f, 0.05f, 0.05f);
glColor3f(1,1,1);
glDrawArrays(GL_TRIANGLES, 0, this->vertexes->size());
glPopMatrix();
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
}
this code actually works, but in certain moments I recreate the vector of floats with new triangles, it can be more or less triangles
before creating new triangles I clear the vector of vertexes, using this functions
std::vector< GLfloat >* MarchingCubesThread::getTriangles(float minvalue_scale)
{
this->generateTriangles(minvalue_scale);
for(unsigned int i=0; i < this->num_triangles; i++)
{
for(int j=0; j < 3; j++)
{
this->vertexes.push_back(this->triangles[i].p[j].x);
this->vertexes.push_back(this->triangles[i].p[j].y);
this->vertexes.push_back(this->triangles[i].p[j].z);
this->vertexes.push_back(this->triangles[i].norm.x);
this->vertexes.push_back(this->triangles[i].norm.y);
this->vertexes.push_back(this->triangles[i].norm.z);
}
}
return &(this->vertexes);
}
void MarchingCubesThread::generateTriangles(float minvalue_scale)
{
this->vertexes.clear();
this->triangles.clear();
this->triangles = MarchingCubesDataset(this->dataset->getMaxVal() * minvalue_scale, *(this->dataset), LinearInterp, this->num_triangles);
}
After playing around creating a new set of new triangles, the OpenGL render updates the mesh well, but in certain moments, I get some garbage triangles, and/or triangles that are from last iteration, and they should be cleared by calling this:
this->vertexes.clear();
this->triangles.clear();
here some screenshots taken in consecutive times:
any clues about what is happening here?, thank you
PD: for a complete source code, this is the public git repository on github:
https://github.com/joecabezas/MemoriaJoeCabezasCode/tree/visualizer

Answer 1

glDrawArrays expects not count of floats in your buffer, but count of vertices.
So correct call should be:
glDrawArrays(GL_TRIANGLES, 0, this->vertexes->size() / 6);
By letting glDrawArrays to draw 6 times more vertices you were displaying garbage after end of valid vector data, and sometimes it was data from previous iteration.