TheGameCreators - CodeBase - Mouse Controlled Camera Rotation

Category: Camera

Version: 1.0

Information

Uploaded: 4th May 2009 18:02

Modified: 1st Jan 1970 01:00

Author: 300happy

Summary

Allows positioning the camera around a 3d point, using mouseXYZ to control rotation, angle, and zoom. Limits Y rotation to prevent going over 90 degrees. Z is also limited to zooming between min and max values. If you've ever played games like Prince of Persia or Assassin's Creed, this will feel very familar to you.

Full Description

This is some pretty simple code, but I spent the afternoon making it as I'm learning DBPro, and thought I would share it since I couldn't find a plain, simple example of doing this. What this code does: Allows positioning the camera around a 3d point, using mouseXYZ to control rotation, angle, and zoom. Limits Y rotation to prevent going over 90 degrees. Z is also limited to zooming between min and max values. If you've ever played games like Prince of Persia or Assassin's Creed, this will feel very familar to you. Should be easy enough to add to your own project, and is as well commented as I could come up with.

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

rem camera rotates around a point

rem Camera Code by Gawain Doell, also known as 300happy on the Game Creator Forums

rem If you use this code, please give credit.  If you find this useful, I'd love to hear

rem	from you.  My email is: smileygames@prodigy.net

remstart

the camera is positioned along a 2d vector of Distance*Height.  This 2d vector is rotated by

the x angle rotation value to allow the camera to swing around the player.

In short, think of it as the camera is mounted to a giant sphere around the player, and can

move along the sphere using it's X rotation and Y position.

Values needed:

camXangle - the x angle rotation of camera around the player

camHeight - the height of the camera

camDist - the distance to place the camera away from the player object

camCDist - the recalculated distance, based on camDist - the absolute value of camHeight.

This formula means that the further away from 0 camHeight is, the closer the camera will

be moved to the object.  This keeps the camera on a sphere around the object.  Without

this calculation, the camera would always be the same distance on the xyz grid, which

isn't what we need because that would allow the player to "zoom out" when the camera

was really high angled or low angled.

camMaxDist - the maximum distance the player can zoom out

camMinDist - the minimum distance the player can zoom in

px, py, and pz are simply the x, y, and z position of the object you wish to follow.

remend

camXangle = 0

camHeight = 0

camDist = 300

camCDist = 0

camMaxDist = 500

camMinDist = 50

rem main loop

rem control camera through mouse position

camXangle = camXangle + ( mousemovex()) rem Add the amount the mouse has moved to the camX angle

if camXangle < -360 then camXangle = 360 rem correct for over 360 values to keep numbers sane

if camXangle > 360 then camXangle = -360

rem for the Y angle movement, we multiply it by the distance / 90.  This means as

rem   the player zooms out, they can move the camera further up and down, preventing

rem   a "slowdown" effect of increasing the distance/angle ratio

camHeight = camHeight + ( mousemovey() * ( (camDist / 90) + 1))

if camHeight > camDist-1 then camHeight = camDist-1 rem correct for over 360 values to keep numbers sane

if camHeight < -camDist+1 then camHeight = -camDist+1

camDist = camDist + (mousemovez()/2) rem Add mouse z to camDist to allow zoom in and out.

if camDist < camMinDist then camDist = camMinDist rem Keep the camDist value above camMinDist.

if camDist > camMaxDist then camDist = camMaxDist rem Keep camDist value below camMaxDist.

rem We calculate the actual distance by placing the camera at the distance, then subtracting

rem   the absolute value of the height.  In layman's terms, the further up or down the camera is,

rem   the closer the camera will be to the player.  This keeps the vector between the camera and

rem   the player the same distance, despite the change of height, and gives us the "sphere"

rem   movement around the player.

camCDist = camDist - abs(camHeight)

rem Now we just plug in both the player position, and our calculated X angle, Distance, and Height.

rem If you want to adjust "smoothness" of movement, just set the 800.0 value to something else.

rem A value of 1.0 will give instant feedback as the camera will teleport to the position over

rem   one frame, but will be jerky.

set camera to follow px, py, pz,camXangle,camCDist,camHeight,800.0,0

rem Now point the camera at the player.  The Set camera to Follow doesn't do this, so by setting

rem   it here, we can be sure the camera will always center our player in the screen.

CodeBase - Mouse Controlled Camera Rotation

Information

Summary

Full Description

DarkBASIC Professional Source Code

Download

Screen Shot

Author

Comments

Author Name:	300happy
CodeBase Entries:	1