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
Upload Code Help
Hi everyone I need some help with a bit of code ive been working with for a while. I am completely s
Not loading image
When this function gets loaded it doesn't load the image just trying to figure out why.
Code:
Call db table from any PHP file
Hi,
I want to be able to call a database table that will be setup in another file called init
explode() function problem maybe
Hi I'm having trouble searching my database. When I type two words in the search field it only searc
division gives infinity anser
int main()
{
int z=0;
int i=1/z;
cout<
}
It doesn't throw a
check if value exists
I have googled this for a while and I am getting lots of different results. Is there a standard meth
losing session vars when arriving from an email link
Hi,
I've got a confirmation script made that sends an email with a link for a user to confirm
A Few Questions
Hi, I want to ask a few questions that I can't seem to find..
1) I'm creating a "shortcu
Best way to read this text file.
Hi.I am planning to make a small application in C# to convert the players from Football manager 2010
Parse String
I need to parse the string below into three variables. How would I do that?
john + 10/20/2008
