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 Like 53 Dislike
Previous forums Next forums
Other forums

data type in column definition
Hi,
I create a table with column called "Direction of Travel code ".
The travel codes in t

Read from a text file after a specific word
Hi all.

I have a text file that looks like the one below.
I know how to open the text fi

need help in update query
hi
i have a dynamic form. i need help in how can i use update query when values from dynamic for

Help pulling in 'id' with "read more" link
I'm trying to create snippets of my articles in the cms I'm creating, and then have them redirect to

Comment Mod System Effects all rows...
Sorry if its confusing but here is whats going on: I have a table in a database called comments and

Line break?
Hi, I'm new to the forum and new to php. I'm not sure if I'm using the correct terminology so here i

Backflush
I am looking for a report in SAP that would give me a list of all parts that are populated with a ba

SCO Unix
I know this might not be the place to ask, but, can anyone tell me if SCO Unix comes with PHP built

Help me with some material on Open Text Overview.
Hi Experts,
Please help me out with some material on Open Text. I have been supporting AP Workf

Operating System
How in PHP or other language can I detect Operating system, ie Windows XP Home, Windows 7 Ultimate,

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash