Camera angles

1. Camera angles • By Chris Hinkey (cmh209) • Standard game camera angle techniques • Camera controllers • Replay camera angles

2. Don’t need to do much if the game is in 2D • When your game is 3D and dynamic is when some problems come in

3. Why we need a good camera system • If done right cameras will not be noticed • If done wrong everyone will notice the slightest flaw • Jittery cameras are not good for fun game play • If you can not see the hero well it is hard to react successfully • Having to fix the camera manually as a user is annoying

4. Requirements of a good camera system • Able to change from user input • Continuously see a clear view of the desired character. • Give special attention to important events • Anticipate characters movements as well as possible • Have a clear view of the path of the character

5. Problems with doing this • Not able to pre-process the environment • Not able to hard code where the camera needs to go • Avoid obstacles from being in between the camera and the character

6. Avoiding obstructed view • How to do this, pros and cons • Raycast collisions • Multi-raycast

7. Attraction points • The camera moves to different pre defined points depending on where the character is located • Works well for small maps • Could possibly cause a jittery camera • Doesn't work as well with a dynamic environment

8. Raycast collisions • Cast out one ray from the character to the camera • Set the camera from any clear path in between the camera and the character • This causes sudden camera movements • Some ways around this?

9. Multi-raycast • Send out four rays from the character around where the camera should go • Should the camera move away from object? • If any of the four rays is hit by an object move away from that object • Should the distance be shortened? • If a clear path can be obtained zoom in

10. More on Multi-raycasts • Smoothing • Used to deal with tunnel situations • Use more zooming in to get around obstacles • Camera transitions (switching characters) • a function occurs to calculate the new camera position for the new character.

11. Intelligent Camera Control • Typical architectures and the problems • A better way to build a camera control system

12. Typical camera architectures • Starts with a few monolithic behaviors that only work well for predictable behaviors • Then fixes are added for certain cases where the camera is broken • This causes a very fragile camera system to code • Trade off between fixing a problem and possibly breaking something else • This focuses more on the subject not the camera

13. A better way to do things • The camera should be thought of as a primary character • Should be based on lightweight behaviors to allow easy design process • Easy addition of new behaviors • Easy way to switch between these behaviors • How do we do all this

14. Implementation • Camera fragment class • Simple math processor • Camera behavior • Updates camera every frame • Receives camera location matrix and generates the new camera position • Generalized code that can be reused in many projects

15. Camera Fragment class • Three update components • position • Height with respect to terrain • Look at and field view (make sure object is in view) • These are to be preformed in order

16. Implementation continued • Camera Controller class • An interface between the game and the Camera Fragment class • In charge of creation/destroying, ordering, activation and updates to different fragments • Will create fragments and put them in a specified order • During each update the controller will cascade through the fragments and generate a new location • No way to turn fragments on and off

17. Adding some AI • There is some lack of flexibility, lets fix that • Rules • Add rules that turn fragments on and off • Used within both controller and fragment classes • Fuzzy rules would add a level of flexibility (too close, not too far) • Works better for systems with fewer fragments • Hard to reorder fragments using this technique

18. State Machines Controller class can have a simple Machine having a rule set to traverse through the states • Each state can be a set of fragments that are active • Allows easy reordering of fragments

19. Other AI • Messaging • This is a good way to keep track of game data in the controller class without using a lot of processing time • Used to trigger rule system • Scripting • Can abstract out code for messaging, switching and ordering • Helpful for doing replays

20. Camera angles in replays • Important for sports games • Give the player the ability to see some of the minor details of the game • Common problems • Different styles

21. Problems • Player must be entertained continuously • Frustration • Accuracy (use better recording schemes ) • Poor performance • Player must feel in control of the replay • Restart, pause, speed control, jump forward and back, and change camera

22. More problems • Boredom • Have a fast paced interesting replay • This is hard to do because you need to create the replay on the fly • A rule based AI system can help in this • These rules can be based on film making camera work

23. Different styles • Intro Camera • Introduces you to the stage and actors • Starts at a distance and then moves toward the subject • When it get to the subject circle around the subject • Only used at the beginning when everything is stationary

24. First person camera • Presents the stage from the subject’s point of view • Useful in racing games • Important to have a frame of reference on the subject • Can be used often but for only short periods of time

25. Follow or Third-person camera • Shows part of the scene and the subject from behind • Many variations of this camera from different heights and distances • Used as a calming section after an action sequence • This camera can be used for up to 50% of the replay

26. Matrix camera • Pauses some or all the action and then circles around the subject • This gives a very dramatic effect • Should be used when something spectacular is happening • Use this camera very sparingly

27. Circle camera • Slowly circles the subject while looking at them • Good for a slow portion of the replay • Can be used as a transition from side to side of the player

28. Still frame camera • As the subject passes, the action is paused at regular intervals simulating photographs • Used in conjunction with photographers on the sidelines

29. Camera switching rules • Don’t cut to the opposite side of a player it is disorienting • Subject should always be in sight • Transitions from camera to camera should be fluid • Special cameras (matrix) should be used sparingly

30. Camera Switching rules cont… • Use follow cameras a lot to serve as breathers between other cameras • All cameras should know where to switch to in case they lose sight of the subject • Make sure the camera types used are appropriate for the game type

31. Some good tools • Switching the subject of each camera • Taking screen shots • Stop subject while the rest of the scene continues • See and change what camera the current camera is going to switch to • Tools to allow an artist or designer to fine tune the replays

32. Freak Out - Extreme Freeride • Snow boarding sports replay • Shows examples of the different kinds of cameras • http://www.youtube.com/watch?v=Axwy2j2E84M

33. Super Mario Galaxy • Good camera implementation • A lot of open field areas without many obstacles • www.youtube.com/watch?v=v7bN-YhEEtI

34. Legend of Zelda: ocarina of time • Boss battle with terrible camera implementation • http://www.youtube.com/watch?v=ef4z7SQi5Oc