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
Page doesn't expand for content
Hi. I've been testing a query I made. It's here http://lapr1.6te.net/inquerito.php
The page doesn
why isn't this PHP code working ???
it's suppose to find a name on the database.
<?php
$s = $_POST["lname&
check if string contain only a-z/A-Z
Is where any way to check if string contains only a-z/A-Z, without writing an array with all possibl
Including calander to page - will not show other months than current??
im trying to add an existaing calander onto a profile page by using Code: <?php include "
How to assign JS screen.width to ASP.Net variable
I've got this ASP.net routine that gets the cookie value of the screen width, but now I need to chan
Adding to the next element in a multidimensional array
Hi, I'm trying to add a value to $node->field_spaces['nid'] where x is the next available spo
generating random codes
Hi guys n gals,
I have a requirement to generate 250,000 unique codes...
These codes a
Must be a string? Huh, what? HELP?
with the following script, I get
Fatal error: Property name must be a string in /home/content/e/
defining website tags
Hi,
What would be the best way to define tags for my site, such as website title, url etc.Problems with returning true or false in eval()'d code
Hi guys,
Would appreciate some help with a problem when running eval() on a function that sho
