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
CHMOD script
Hi,
I need a script to read all files in a folder and set to 777.
Can anyone help out
HeaderSelectedCssClass not working
I have an accordian where I have a drop down list in the first pane and a grid in the second pane.
Syntax error
hi im having a little trobble with this script
-------------------------------------------------
Reditecting pages based on logic
Newbie here, apologies in advance!
I am trying to use the header function to forward one of a
Array disappearing in foreach loop
Okay, I have this problem where an array will become undefined in a foreach loop.
Here is the
Hyperlink is adding an extra gap to variable
Hi, here's my problem..
I have a php generated page with a hyperlink which opens in a new win
Problem related to Creation of PDF File?
Hi All,
I am facing a problem related to creation pdf file. when I am creating a pdf file of do
PHP mail() returns true but doesn't work
First off I apologize if this is a newbie question, and I generally don't like asking questions that
Not capturing all the information we require in the form.......
Hi Guys,
I was wondering if you would share some more of your knowledge today, I'm hoping it
PHP webpage & array print issue
I have this code running, and it works perfectly … however, see my bottom bit about what I see
