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.

Did you know?Explore Trending and Topic pages for more stories like this.
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

Help with parsing this html
Hi,
I've got some html i just need a couple of strings from.. argh, it's freaking me out. I've t

mysq_num_rows
Hi,

I want to use:

Code: if(mysql_num_rows($ergebnis2)==2)
how can the value 2, be

Upload simple problem
Really confused!! I run once and it worked, but when i tried today...it didn't work

Which par

help with database debug pls
Parse error: syntax error, unexpected T_ELSE in /home/content/m/e/s/mesick/html/students/05/php/chec

SHOW TABLES Help
Hi all

I have the following

Code: [Select]<?php
$sql = "SHOW TABLES&quo

Problem with PHP code- simple contact form
Hi Folks,
I'm relativily new to PHP; I know HTML and CSS stuff but I have a problem- I have a co

difference between datetimes
($row['totime']-$row['fromtime'])/60

this is giving me 0

example of totime and fromtim

Multiple Do / While Statements?
I'm still very new to PHP, and running in to a problem when trying to execute a do/while loop inside

Phase Error I can't seem to find :(`
Hey guys, I can seem to find my phase error on this. I am getting this error

[error]
Pars

phpMailer not working ..........
HI,
I was playing with the phpMailer script and tried to send a smiple mail using their test scri

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