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

Problem with array max size.
Hi to everyone,
I've got a homework about filling a bidimensional array un spiral shape, I alre

Simple program to copy files between two computers over the web
I use logmein free and often need to move files between my two computers. Generally, I move the file

MySQL query problem
When I try to run the following piece of code, I get this error:
QuoteWarning: mysql_query(): sup

C problem struct and string
Hi guys,

This is my first post and I'm hoping the experts here can help me solve my problem.<

All possible combinations of String in PL/SQL
Hi All,

Could you please explain the logic of getting all possible combinations of String

square instead of number
Hello
I do not know why but this code seems to work fine only in my xampp local insallation but n

How to search for several parameters from objects in a database?
I have a database with lots of information about objects.
Now I would like to search for 4 or 5 p

Simple AND question
Hello,

I've got following code:

Code: if(strpos($row[13],"http://")

Hotlinking Picasa as the image folder of a website
Hi there PHP freaks, I would like to create a private album in Picasa to use it as the image folder

Set Categories
I am creating a submission form for somebody to come in and submit products. These products are sep