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 
53 
Other forums
str_replace help
Hey there,
I'm a PHP newb, I'm having troubles with the str_replace function. I want to clean
re calling a function without including file
Hi,
i am new to programming in php, i was just checking the wordpress code and found out in the w
cURL proxy
Okay here is the thing... i know how to add proxys
Code: curl_setopt($ch, CURLOPT_PROXYTYPE,
utl_file open error
i have file in the unix path
Path /popdev01/pop/popdevb/tfi/
File name
Comparing two dates
Hi Guys
I have two dates I want to compare. Below is my current implementation. The problem with
Forgot password won't work
My forgot password thing is not working properly. It is giving me this errorMailbox unavailable. The
distinct rows
Hi
version 10.2.0.3
I have a query output something like the following
ID
Php If in MySql query (hiding labels if a field is empty)
Okay, I've been trying to do this for a while, and I'm finally going to ask for help so I can get th
Filename like the user name
I am creating a form and storing the values in file. Could anyone please tell me how to write a code
mysql_real_escape_string making variable equal nothing
i post a form and i post the variable:
Code: $var = $_POST[variable];then i echo $var its what i
