Hi!

Quick question: how DrawNode::drawDot is able to draw a perfect circle if only two triangles are employed to draw the dot?

Thanks!

```
void DrawNode::drawDot(const Point &pos, float radius, const Color4F &color)
{
unsigned int vertex_count = 2*3;
ensureCapacity(vertex_count);
V2F_C4B_T2F a = {Vertex2F(pos.x - radius, pos.y - radius), Color4B(color), Tex2F(-1.0, -1.0) };
V2F_C4B_T2F b = {Vertex2F(pos.x - radius, pos.y + radius), Color4B(color), Tex2F(-1.0, 1.0) };
V2F_C4B_T2F c = {Vertex2F(pos.x + radius, pos.y + radius), Color4B(color), Tex2F( 1.0, 1.0) };
V2F_C4B_T2F d = {Vertex2F(pos.x + radius, pos.y - radius), Color4B(color), Tex2F( 1.0, -1.0) };
V2F_C4B_T2F_Triangle *triangles = (V2F_C4B_T2F_Triangle *)(_buffer + _bufferCount);
V2F_C4B_T2F_Triangle triangle0 = {a, b, c};
V2F_C4B_T2F_Triangle triangle1 = {a, c, d};
triangles[0] = triangle0;
triangles[1] = triangle1;
_bufferCount += vertex_count;
_dirty = true;
}
```