# Controlling the Camera¶

## Default Camera Control System¶

By default, Panda3D runs a task that allows you to move the camera using the mouse.

The keys to navigate are:

Mouse Button

Action

Left Button

Pan left and right.

Right Button

Move forwards and backwards.

Middle Button

Rotate around the origin of the application.

Right and Middle Buttons

Roll the point of view around the view axis.

Go ahead and try this camera control system. The problem with it is that it is sometimes awkward. It is not always easy to get the camera pointed in the direction we want.

### Update the Code¶

Instead, we are going to write a task that controls the camera’s position explicitly. A task is nothing but a procedure that gets called every frame. Update your code as follows:

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 from math import pi, sin, cos from direct.showbase.ShowBase import ShowBase from direct.task import Task class MyApp(ShowBase): def __init__(self): ShowBase.__init__(self) # Load the environment model. self.scene = self.loader.loadModel("models/environment") # Reparent the model to render. self.scene.reparentTo(self.render) # Apply scale and position transforms on the model. self.scene.setScale(0.25, 0.25, 0.25) self.scene.setPos(-8, 42, 0) # Add the spinCameraTask procedure to the task manager. self.taskMgr.add(self.spinCameraTask, "SpinCameraTask") # Define a procedure to move the camera. def spinCameraTask(self, task): angleDegrees = task.time * 6.0 angleRadians = angleDegrees * (pi / 180.0) self.camera.setPos(20 * sin(angleRadians), -20 * cos(angleRadians), 3) self.camera.setHpr(angleDegrees, 0, 0) return Task.cont app = MyApp() app.run() 

The procedure taskMgr.add() tells Panda3D’s task manager to call the procedure spinCameraTask() every frame. This is a procedure that we have written to control the camera. As long as the procedure spinCameraTask() returns the constant AsyncTask.DS_cont, the task manager will continue to call it every frame.

In our code, the procedure spinCameraTask() calculates the desired position of the camera based on how much time has elapsed. The camera rotates 6 degrees every second. The first two lines compute the desired orientation of the camera; first in degrees, and then in radians. The setPos() call actually sets the position of the camera. (Remember that Y is horizontal and Z is vertical, so the position is changed by animating X and Y while Z is left fixed at 3 units above ground level.) The setHpr() call actually sets the orientation.

### Run the Program¶

The camera should no longer be underground; and furthermore, it should now be rotating about the clearing: