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
mysql_real_escape_string making variable equal nothing
i post a form and i post the variable:
Code: $var = $_POST[variable];then i echo $var its what i
xml element exists
Code: [Select]<?xml version="1.0"?>
<Addresses>
<
using a loop help
Hi guys , i need some help. I have this loop :
while ($row = mysql_fetch_assoc($Result)) { ?&
An odd assignment statement. Can someone explain this assignment to me?
What purpose is served by the bit of code between the two equal signs in the $installurl set? Is th
Session is not saving
I am not trying to do anything too fancy, I am just trying to get some $_SESSION data to save and us
a very simple php header question (sorry!)
Firstly...I do apologise if this annoys anyone....a header error
I'm do not know php &
Using CSS to format MySQL query
Hi,
If i want to have a news page on my site, which displays all records of a table in descen
media recovery
Hi,
i startup the database i got the error
SQL> startup
ORACLE instance started.
ImageCreate()
When I create an image and add text to it I want my text to be replaced with a PNG image, because th
Line break?
Hi, I'm new to the forum and new to php. I'm not sure if I'm using the correct terminology so here i