TheGameCreators - CodeBase - 3d movement with inertia in a frictionless environment

Category: 3D Maths

Version: 1.0

Information

Uploaded: 8th Feb 2004 10:46

Modified: 1st Jan 1970 01:00

Author: Philip

Summary

This is example code to show how to move a camera in 3d with inertia. For example, movement like the I-Wars space games.

Full Description

There are plenty of remarks in the code. Feel free to use as you wish.

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

Remstart

PJY's attempted example of pseudo-Newtonian style movement for Mr. Silent Phoenix

Remend

Rem PJY - standard setup

sync on

sync rate 30

autocam off

backdrop on

Rem PJY - make cube to give the camera some reference point to show the movement

make object cube 1, 50

position object 1, 0, 100, 500

Rem PJY - we'll use the default camera because I'm feeling lazy

position camera 0, 0, 0, 0

Rem PJY - create some vector3 data items to hold the camera movement data

camera_position = 1

camera_new_movement = 2

camera_old_movement = 3

camera_movement = 4

null = make vector3(camera_position)

null = make vector3(camera_new_movement)

null = make vector3(camera_old_movement)

null = make vector3(camera_movement)

Rem PJY - calculate the centre of the camera's screen for use in the pick screen command below

width = screen width() / 2

height = screen height() / 2

Rem PJY - declare a few float variables - you just never know when they'll come in handy

robk# AS float

ianm# AS float

tca# AS float

Rem PJY - main loop

Rem PJY - deal with human input

if upkey() = 1 then pitch camera up 0, 1

if downkey() = 1 then pitch camera down 0, 1

if leftkey() = 1 then turn camera left 0, 1

if rightkey() = 1 then turn camera right 0, 1

Rem PJY - update camera position vector

set vector3 to camera position camera_position, 0

Rem PJY - normalise the camera_movement vector otherwise on the last loop executed the camera_movement will increase exponentially

Rem PJY - and that will cause the camera to shoot off faster than a Robin Reliant on steroids

normalize vector3 camera_movement, camera_movement

Rem PJY - and transfer old camera movement into a temporary storage vector

set vector3 camera_old_movement, x vector3(camera_movement), y vector3(camera_movement), z vector3(camera_movement)

Rem PJY - now calculate the 3d vector which represents the camera's orientation if the player presses the thrust key

if returnkey() = 1

pick screen width, height, 2

robk# = get pick vector x()

ianm# = get pick vector y()

tca# = get pick vector z()

set vector3 camera_new_movement, robk#, ianm#, tca#

endif

Rem PJY - right now add the old movement (if any) to the new movement (if any) to get the sum total new movement vector

add vector3 camera_movement, camera_old_movement, camera_new_movement

Rem PJY - and now add the new movement vector to the camera's current position to find out the new X, Y, Z coords of the camera

Rem PJY - which to save space I shall rather confusingly save straight back in the camera_movement vector again (overwriting the previous data in there)

add vector3 camera_movement, camera_position, camera_movement

Rem PJY - and now re-position the camera at those new coords

position camera 0, x vector3(camera_movement), y vector3(camera_movement), z vector3(camera_movement)

Rem PJY - display info for user comprehension

x = 0

y = 0

text x, y, "X: " + str$(x vector3(camera_position)) + " Y: " + str$(y vector3(camera_position)) + " Z: " + str$(z vector3(camera_position))

y = y + 15

text x, y, "Cam Move X: " + str$(x vector3(camera_movement)) + " Cam Move Y: " + str$(y vector3(camera_movement)) + " Cam Move Z: " + str$(z vector3(camera_movement))

y = y + 15

text x, y, "Cam NewMove X: " + str$(x vector3(camera_new_movement)) + " Cam NewMove Y: " + str$(y vector3(camera_new_movement)) + " Cam NewMove Z: " + str$(z vector3(camera_new_movement))

y = y + 15

Rem PJY - give user a clue what the keyboard does

text x, y, "Arrow keys to control camera, return is the move key"

y = y + 30

Rem PJY - put a stupid statement on the screen

text x, y, "Its sort of real physics, Jim, but not as we know it ... "

Rem PJY - and update screen

sync

loop

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Author Name:	Philip
CodeBase Entries:	11

CodeBase - 3d movement with inertia in a frictionless environment

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DarkBASIC Professional Source Code

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