• FEATURED

View more

View more

View more

### Image of the Day Submit

IOTD | Top Screenshots

### The latest, straight to your Inbox.

Subscribe to GameDev.net Direct to receive the latest updates and exclusive content.

# How do I read a CubeMap on CPU side? (Or how the GPU texCube function read a pixel from a CubeMap)

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

2 replies to this topic

### #1tpastor  Members

Posted 14 April 2012 - 07:37 AM

I need to extract the one pixel from a CubeMap (I already have the 6 textures extracted) using the normal vector. How can I achieve this ?

I want something very similar to what texCUBE(link) does in GPU but in CPU.

I am using XNA and C#, but an example in any language may help.

### #2mrhyperpenguin  Members

Posted 14 April 2012 - 09:27 AM

The largest component of the normal vector tells you which face it intersects. Next divide the normal vector by the absolute value of the largest component. Then scale and shit the other two components into the usual range for uvs ([0, 1] on each axis).

For example if you had the vector <-3, -1, 2>.

First it intersects the negative x face. Then

<-3, -1, 2> / |-3| = <-1, -1/3, 2/3>.

Finally just scale the remaining two components from [-1, 1] to [0, 1], <-1/3, 2/3> * 0.5 + 0.5 = <2/3, 5/6>. And similarly for each other face.

Victor

### #3tpastor  Members

Posted 14 April 2012 - 09:45 AM

Thanks a lot !

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.