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

How can use this array as a key?
Say I have this array for example:


print_r($array);

Prints:
Code: [Select]Array

SQL Query/echo not working
Hey all,

I'm trying to run (what I thought) was a simple operation and it isn't working. I h

Secure pages Sessions vs. Cookies & session_destroy() help
Im new here and new to PHP, I hope you can help me with some questions.

Im writing my web ap

Spaghetti Code
So.

I've pretty much reached the point where I have so many isset s on one page that I can't

I am stumped
OK. Here is what I am trying to do. I have the conditions set, and if the conditions are met, I want

HTML form problem
Ive made a form to that i want to send to my email via PHP. but when it send only the name's etc sen

Calender Not Opening
The following code is not loading the javascript calender in another window. It's not doing anything

ORA-01017: invalid username/password; logon denied
Dear All,

I am facing problem in taken backup from db13 it comes up with the following l

extending tidy
I have problem with type-hinting and extending tidy. This code creates error:
Code: class cMyTidy

Multithreading in Oracle (Java, SQLJ, Pro*C,??) on 10g
I am investigating how to run a Java stored procedure in multithread mode.
I know that if I chang

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