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.

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.

Your Answer:

Login to answer

Other forums

Getting PHP to ammended the selected in option field
Hey Guys

thanks for everyones help so far. This site and its users are oozing awesomness.

iMatch stored value with the current value in a loop
Hello,

I have a MySQL db were I store articles in.

I have a form to fill these article

mysql_query returning boolean instead of mysql ressource
Hi,

I seem to have a weird issue with the php command mysql_query. I pass 2 arguments the que

Need help to identify this error please
:confused:Can anyone help me tell what this error message means? Maybe tell me where to look to fix

Include with Parameters
In a particular page I would like to include a file that requires $_GET parameters.

when I go

Selecting an "empty" date formated field
How do you select an "empty" date field? I've tried the few ways I can think.
SQL> select

Uploading files/images via forms
Hey all, I am building a database for work that will contain some minor data on plant species along

Inserting the current date/time while submitting the forum
What do I need to add below to update the current date/time? I have a field in the database called d

please help me in this update statment
hi every one

if I have table and this data in it

id name
10

Operator precedence assistance.
I did a quick Google search and couldn't quite find the answer I wanted in terms I could understand,