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

* Gridview and Detailsview in UpdatePanel, insert mode problem
I have a GridView and DetailsView working together. When a record from Gridview is selected, Detail

Can I call a class inside a function?
I have a class written in another file that handles my image resizing.

Can I do this (php say

pls clear my confusion
Hi friends,

Pls solve my query .

what is the exact use of Scope Resolution Operator( i

for loop without same $i digits?
Hi,

Can some guru please advise how can I accomplish this with a simple for loop ?

I

upload photo limits
ive got a upload photo script and im just trying to make more secure currently it limits size and as

Day of week
I am using PHP version 5.0.5
I have a varaible ($DATE (date format yyyy-mm-dd)) that is being inc

Comment Mod System Effects all rows...
Sorry if its confusing but here is whats going on: I have a table in a database called comments and

Why is this function returning a false value when it shouldn't be??
This is in an include file. I want it to check a value in an html form and see if it's just white s

php ajax - two drop down list with a submit button
i have created a form with 2 drop-down list and a submit button. I would like to know how to pass th

Better Method of a Member Cloud
I assume most people know how tag clouds work, where the tags most used are bigger and the least use

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