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

Page not Loading After Test
Hey All

It seemed that an inlcude statement wasn't working for some reason, so I tried a more

Price in PR
Dear Experts,
Why we have to enter the price in the PR, and why there is no free goods indicato

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

Batch update record with Pagination
Hoping someone can help me with this issue I'm having, im trying to batch update records from a resu

Can anyone give me some link on .htaccess tutorial
i wish to have friendly url using .htaccess, but no idea yet about this

Hope that anyone cou

Problem with variable declaration in switch statement
Hello, I am having some trouble assigning a value to a variable inside a switch statement. What I a

. and .. appearing instead of pictures
First of all, thanks very much for providing this forum. It is very much appreciated!

My son

Wierd echo error?
Hi, i got the most wierd php error ever and i don't know why..
Code: echo "<t

"SEO" URLs
Hey, I'm wondering how to go about creating and using these types of URLs. I'm presuming it's PHP th

Php Mysql Page Loading Notice
Hi all,

I was wondering if there is a way (Sure there is) of showing a message or an image wh