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

Breaking results into week blocks
I have a set of dates (and times), which are returned from a mySQL query.

These usually span

New Login Script
Hi all, i attempted to create a whole new login script witch isnt working for some reason i dont kno

selection tool on raster image
Hi!
I have to implement in my app a selection tool which lets users to select region of any shape

How would I protect......
I have a from, actually, a good amount of forms. How can I make it so you can't type the characters:

how to easy edit text, with box? Help.
Hi.
I have a little problem. I'm doing a webpage for my aunt and I would like to make it as easy

Count Session and Trigger Events
I am New in PHP, seeking a method to count logged users by counting the sessions or any …, is

Passing Variables
What I'm wanting to do is when the user clicks on Arenas it will know the name of the country it's w

Code error with Index.php
Error: Parse error: syntax error, unexpected T_STRING, expecting ',' or ';' in /home/runevid/public_

Odd or Even
Inside of a while loop I need to echo several rows of info...easy enough.

In the loop (for th

Help on code output
My CODE:

Code: [Select] echo "<phone>".$line["phone"].&qu