Floating Point Precision Loss


Posted on 16th Feb 2014 07:03 pm by admin

I'm writing a program to draw a three-dimensional cube (with a corner cut off) without using any 3D graphics APIs. The only API call I make is win32's SetPixel()

Everything is going great. I've drawn lines, faces, and even the entire cube. Then rotation came along.

For some reason, when I rotate my cube, it begins to shrink. I became confused, then I realised something. Floating point numbers are truncated.

Here's some code that is fired everytime the user presses 'X' on the keyboard.

Code: p->setY( p->getY() * cos(5.0/180.0*PI) - p->getZ() * sin(5.0/180.0*PI)); p->setZ( p->getY() * sin(5.0/180.0*PI) + p->getZ() * cos(5.0/180.0*PI));

p is a Point object that I created. Here the Y value and the Z value of the Point are being set. The problem is everytime X is pressed, and this code is fired, a small amount of precision is lost. As a result, the cube shrinks.

I'm really completely stumped. I remember when studying assembler that floating point numbers can be truncated or rounded. I think rounding would solve my problem. Since 50% of the time the value would round up, and 50% of the time the value would round down.

Whereas with truncation values are always lost, and never gained.

No comments posted yet

Your Answer:

Login to answer
213 Like 53 Dislike
Previous forums Next forums
Other forums

Newb advice
Hi all,

I'm a flash front end designer and I've taken on a project that needs some back end p

What am I missing here? Help!
Hello all!. I can't seem to get this working right. Well - it renders right, but something is goin

Array question
Does anyone know how to create a program that takes the $ amount for 8 different departments and gi

Help on code output
My CODE:

Code: [Select] echo "<phone>".$line["phone"].&qu

quotes changing
hi all

in my content

opening quotes " changes to “

close qu

Help with forum quoting?
Hi im working on a forum and I have alomost finished it but i want a user quote system like twitter

how to use two buttons with php
hi i have one form. there are three fields which are to be filled by the user. and then there are tw

standard ALV application toolbar, into custom report....
HI,

I have a question regarding displaying standard ALV menu path and application toolbar

question about n
I was looking at some of the things you could do with php and one of the things I have tried is n.<

how to remove in php string display
My code is $message="We're looking at developing our website."; $body= "My mess

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash