Drawing in 3D with the mouse

In this recipe, we will draw with the mouse on a 3D space. We will draw lines when dragging the mouse or rotate the scene in 3D when dragging and pressing the Shift key simultaneously.

Getting ready

Include the necessary files to draw using OpenGL, as well as the files needed to use Cinder's perspective, Maya camera, and poly lines.

#include "cinder/gl/gl.h"
#include "cinder/Camera.h"
#include "cinder/MayaCamUI.h"
#include "cinder/PolyLine.h"

Also, add the following using statements:

using namespace ci;
using namespace ci::app;
using namespace std;

How to do it…

We will use the ci::CameraPersp and ci::Ray classes to convert the mouse coordinates to our rotated 3D scene.

1. Declare a ci::MayaCamUI object and a std::vector object of ci::PolyLine<ci::Vec3f> to store the drawn lines:

   MayaCamUI mCamera;
   vector<PolyLine<Vec3f> > mLines;

2. In the setup method, we will create ci::CameraPersp and set it up so that the point of interest is the center of the window....